Kei-Ichi Okuyama

Kyushu Institute of Technology · Department of Applied Science for Integrated System Engineering

In this study, we focus on 3D-printed PEEK/CFRTP (Carbon-Fiber-Reinforced Thermoplastic) and PEEK (Polyether Ether Ketone) materials as new space materials. In space, there are intense ultraviolet (UV) rays that are weakened by the atmosphere on Earth, so it is essential to understand the degradation of materials due to UV rays in advance. Therefor...

On 29 October 2018 at 13:08 Japanese Standard Time was successfully launched the Greenhouse gas Observing SATellite (GOSAT-2) from the JAXA Tanegashima Space Center. Piggy-back with the GOSAT-2 satellite in a circular (623 km), polar synchronous orbit, was launched the 22 kilogram mass satellite Ten-Koh (http://kit-okuyama-lab.com/en/ten-koh/). It...

During the last decade, several small satellites and space probes have been developed, new design challenges have to be faced such as small size, reduced mass, thermal management and mechanical constraints with their limited ability to carry a certain number of missions and payloads. Combined all these challenges for the actual battery’s technology...

Satellites must endure the hostile environement during their launching to space via rocket; therefore, they should be exposed to the real launch conditions for ground testing, including all subsystems and components which should be carefully tested. Several solid-state-ceramic batteries have been selected to be evaluated under the launch environmen...

The extreme heating environment during re-entry requires an efficient heat shield to protect a spacecraft. The current method of manufacturing a heat shield is labor intensive. The application of 3D printing can reduce cost and manufacturing time and improve the quality of a heat shield. A 3D printed carbon fiber/polyether ether ketone (CF/PEEK) co...

Electric Double-Layer Capacitors (EDLC), also known as supercapacitors or ultracapacitors, are being considered as an energy storage option in space applications because they can operate over wider temperature ranges, and have longer lifetimes and higher power densities than batteries. However, the limited number of studies concerned with the suita...

The desired capabilities of small satellites to enable their applications in communication, earth observation and new scientific instruments require advanced energy storage to face the design’s challenges with the constraints of volume and mass. Small batteries with high energy density may be the solution. New lithium-ion battery technologies are b...

The low Earth orbit (LEO) environment exposes spacecraft to factors that can degrade the dimensional stability of the structure. Carbon Fibre/Polyether Ether Ketone (CF/PEEK) can limit such degradations. However, there are limited in-orbit data on the performance of CF/PEEK. Usage of small satellite as material science research platform can address...

When a spacecraft orbiting the earth enters the earth's atmosphere, it is exposed to an aerodynamic heating environment. The outer surface of the spacecraft has been covered with a carbonized ablator made of a CFRP to prevent this heat input from entering this spacecraft. From the research conducted so far, it has been found that a CFRTP has a spec...

Spacecraft employs heat shield as protection from high heat during reentry into Earth atmosphere. However, current heat shields are labor intensive to manufacture and cost prohibitive. Additive manufacturing technology or 3D printing allows rapid manufacturing, reduced cost and design flexibility. Hence, a new thermal protection system (TPS) was pr...

Small satellite missions are disrupting the satellite industry in the recent years, by following a nontraditional-space approach with low cost, fast delivery, and innovation through the application of commercial electronics and materials revolution into space systems. However, there are still challenges that make the path for accessing space via a...

Nowadays, it has become possible for universities and new businesses to launch satellites of reduced size and cost fulfilling viable missions. Nevertheless, there is still a considerable failure rate that reduces the expected lifetime of these spacecraft. One of the main causes of failure is the power system. Redundancy is one of the main options t...

Ten-Koh is a 23.5 kg, low-cost satellite developed to conduct space environment effects research in low-Earth orbit (LEO). Ten-Koh was developed primarily by students of the Kyushu Institute of Technology (Kyutech) and launched on 29 October 2018 on-board HII-A rocket F40, as a piggyback payload of JAXA’s Greenhouse gas Observing Satellite (GOSAT-2...

Ten-Koh is a small lean satellite developed by Kyushu Institute of Technology which was launched in piggyback with GOSAT2 and KhalifaSat on 29th October 2018, at 13:08 Japan Standard Time through the H-IIA-202 rocket of Tanegashima space center of Japan, that exploits different progress techniques to accomplish less cost growth and rapid delivery....

The Low Earth Orbit (LEO) environment exposes spacecraft structures to ultraviolet (UV) radiation, atomic oxygen (AO), vacuum and temperature variation. Carbon Fiber/Polyether Ether Ketone (CF/PEEK) composite can be an ideal material to counter such factors. However, there is limited data on the performance of CF/PEEK composite in a LEO environment...

As small satellites are becoming more widespread for new businesses and applications, the development time, failure rate and cost of the spacecraft must be reduced. One of the systems with the highest cost and the most frequent failure in the satellite is the Electrical Power System (EPS). One approach to achieve rapid development times while reduc...

The coking phenomenon within a lightweight carbon-phenolic ablator exposed to the heating environment of air is investigated. The existing one-dimensional charring ablation analysis code is modified so that the coking behavior of the ablator can be calculated as well as the thermal response behavior within a lightweight carbon-phenolic ablator. The...

Micro satellites must survive severe mechanical conditions during their launch phase. One design requirement for rockets is the stiffness requirement, i.e. the natural frequencies requirement. In the early stages of satellite development, presumption of the natural frequency of a satellite may be difficult. The material used for the structure of ma...

Micro satellites must survive severe mechanical conditions during their launch phase. One design requirement for rockets is the stiffness requirement, i.e. the natural frequencies requirement. In the early stages of satellite development, presumption of the natural frequency of a satellite may be difficult. The material used for the structure of ma...

Global warming continues to be a major concern around the world. The Integrated System Engineering Lab in Kyushu Institute of Technology (KIT) launched a small balloon to the stratosphere to study the ozone layer and greenhouse gases in order to understand global warming. It is a part of the Project Based Learning (PBL) course in KIT. The project m...

Micro satellites must survive severe mechanical conditions during their launch phase. One design requirement for rockets is the stiffness requirement, i.e. the natural frequencies requirement. In the early stages of satellite development, presumption of the natural frequency of a satellite may be difficult. The material used for the structure of ma...

Since the specific strength and the specific elasticity of carbon fiber reinforced plastics (CFRPs) are the greatest in practical materials, they are used abundantly in transport structures. This CFRP can also be used for a pressure vessel which stores liquid hydrazine, the required burst pressure is approximately 22MPa. Many researchers have been...

Different plasma wind tunnels have been fabricated for developing reusable space probe transportation systems during the Earth atmospheres re-entry phase. Several probes faces a loss of communication due to the plasma sheath occurred, caused by high velocity, heat flux and wall temperature in front of the probe. The purpose of the experiment to stu...

During the re-entry flight, the radio signal will be interrupted, which is commonly referred to as the communications blackout. Once the plasma sheath forms in the stagnation region of a small space probe, the probe losses more than 70 percent of its downlink data. This shows that the attenuation of the radio signal is very high during the re-entry...

During the re-entry flight, the radio signal will be interrupted, which is commonly referred to as the communications blackout. Once the plasma sheath forms in the stagnation region of a small space probe, the probe losses more than 70 percent of its downlink data. This shows that the attenuation of the radio signal is very high during the re-entry...

Entering a planetary atmosphere is one of the most claim missions as the space probe faces a loss of communication, acknowledged as communication blackout, due to the plasma sheath occurred, caused by temperatures of several thousand degrees in front of the space probe. This paper presents a study about a new method of communication called end of r...

Entering a planetary atmosphere is one of the most claim missions as the space probe faces a loss of communication, acknowledged as communication blackout, due to the plasma sheath occurred, caused by temperatures of several thousand degrees in front of the space probe. This paper presents a study about a new method of communication called end of r...

During the re-entry flight phase, the radio blackout denotes to the communication interruption due to the plasma sheath in stagnation region. When the probe enter into the Earth’s atmosphere, it caused by shock wave layer is formed due to the high velocity and high heat flux. The paper define an approach how the end of radio signal occurs and to so...

The effects of heat load, ablator density, and backup structure, etc. upon the heat shield performance of the lightweight phenolic carbon ablators named LATS were investigated using a one-dimensional ablation analysis code. The ablator density was assumed to be from about 260 to 1000 kg/m³. Heat flux time histories of a rectangular pattern were ass...

A small, deep-space probe, Shinen2, was developed under collaboration with the Kyushu Institute of Technology and Kagoshima University. The Shinen2 was launched by an H-2A rocket as a piggyback space probe with the JAXA's (Japan Aerospace Exploration Agency) asteroid probe, Hayabusa2, in 2014. The outer shape of the Shinen2 has a quasi-spherical di...

It's a grand opportunity to build new small deep space probe called Shinen2, developed by Kyushu Institute of Technology (KIT), in corporation with the different companies and institutions of engineering in Kagoshima University (Japan), NASA Johnson Space Center, was launched by the rocket H-IIA of Japan Aerospace Exploration Agency (JAXA) with Hay...

A small deep space probe, Shinen2 was produced by the Kyushu Institute of Technology in collaboration with Kagoshima University. Shinen2 was lunched by an H2-A rocket as a piggy-back space probe with Hayabusa-2 of JAXA’s probe in 2014. Shinen2 is exploring in the deep space beyond the moon. Shinen2 has three missions: the first mission is a structu...

When we develop a space probe, are needed to carry out its orbit analysis. Space industries and space agencies they have been using the System Tool Kit (STK) for these orbit analysis. Most of satellite projects were used this software. An allowable mass demand of a rocket to an ultra-small space probe is very severe, for this reason a throughput an...

For protecting the spacecraft against the severe heating during the atmospheric reentry, the ablative materials are commonly used as thermal shield. Recently, a new lightweight CFRP called the lightweight ablator series for transfer vehicle systems (LATS) was developed. Since LATS contains a resin that undergoes thermal decomposition by heating, cl...

Shinen2 is a deep space probe, developed by Kyushu Institute of Technology (Japan) in collaboration with Kagoshima University (Japan), which was launched on 3rd December 2014, being the first ultra-small deep space probe in the world which uses an amateur radio communication system in deep space. It has a quasi-spherical shape which allows a more u...

"Hayabusa" is one of the Satellite which explore planets. To return samples of planets and protect them from great heating when re-entry to the atmosphere of Earth, the heat shield of the capsule is developed so far. However, the heat shield of the capsule is needed to reduce weight and to keep the heat resisting property from the viewpoint of cast...

Kyushu Institute of Technology has been developing the lightweight ablator series for transfer vehicle systems (LATS) as a thermal protection system at the time of reentry. This LATS is composed of a carbon fiber reinforced plastic (CFRP) and it has various densities. In this study, we have made two LATS materials which the specific densities are a...

The outer wall of re-entry vehicles is covered with heat shield materials in order to protect them from severe aerodynamic heating. An ablator is a type of heat shield material effective for re-entry vehicles. In particularly an ablator made of Phenolic carbon fiber-reinforced plastics (CFRP) is known to possess superior resistance against severe a...

Gas turbine engines are utilized as jet engines of aircraft and industrial gas turbines. Then, heavy and expensive Ni-base super alloys are used for a material of the turbine blade due to very severe environment. Therefore, we are applying a CFRP for the material of the turbine blade instead of the alloy in order to reduce the weight and the expens...

The laboratory of Pr. Okuyama, Kyushu Institute of Technology, analyzed the mechanical behavior of their small satellite, しんえん2 (Shinen 2) before its launch. The satellite used CFRTP (Carbon Fibers Reinforced Thermo-Plastic), a structural material presenting excellent properties in terms of impacts protection, thermal isolation, toughness and light...

MicroDragon (MDG) is the first 50-kg satellite developed by researchers of Vietnam National Satellite Center (VNSC) in collaboration with Okuyama laboratory to develop the structure. The satellite shall be launched by H2A rocket in beginning of 2018. The main mission of this satellite is the observation of ocean color to assess coastal water qualit...

Small satellites made by universities and small private companies are getting main streams in Japanese and global space developments. Some universities in Japan now have excellent potential and actually realized many fruitful outcome. Meanwhile reentry vehicles in Japan are not vigorous as before ceasing HOPE-X project. Researchers for heat resista...

When temperature suddenly changes an ablator material inside, a predicted in-depth temperature using the thermal conductivity that measured in the steady state, it does not accord it to measured value strictly. One of these reasons is because an input energy to a material is spent by the conductive heat transfer, the increase of the internal energy...

In case of the high-speed flight within the atmosphere, the orbital and suborbital spacecrafts suffer great aerodynamic heating. Using an efficient thermal protection system (TPS) is important for maintaining the structural integrity, but also for preserving the payload and onboard devices. The ablative materials are commonly used as thermal shield...

An ultra-small probe which was named Shinen2 will be launched a H2A rocket with JAXA's asteroid probe the Hayabusa2. The Kyushu Institute of Technology has been developing the Shinen2 system with Kagoshima University. The purpose of this Shinen2 development is the establishment of a deep space communication method and a new structure designing meth...

This paper presents a new location determination in an indoor environment is a contest that appearances the wireless communication. The concept of indoor cooperative positioning was established in order to provide the user's location inside buildings or laboratories during a necessity where Global Navigation Satellite System (GNSS) facilities are n...

The steroid receptor (SR) complex contains FKBP51 and FKBP52, which bind to tacrolimus (TAC) and cyclophilin 40, which, in turn, bind to cyclosporine (CYA); these influence the intranuclear mobility of steroid‐SR complexes. Pharmacodynamic interactions are thought to exist between steroids and calcineurin inhibitors (CNIs) on the SR complex. We exa...

The effects of density, thickness and heat load upon the heat shield performance of the lightweight phenolic carbon ablators named LATS (Lightweight Ablator series for Transfer vehicle Systems) were examined quantitatively for both arc-heated test and re-entry heating conditions using a one-dimensional ablation analysis code. Thermal conductivity v...

A new class of lightweight carbon fiber reinforced plastic (CFRP)–-the lightweight ablator series for transfer vehicle systems (LATS)–-has recently been developed. The LATS is fabricated by heating and pressurizing a material in which resin is impregnated in the laminated carbon fiber felt. A characteristic required to ensure the excellence of a co...

An existing computer code named super charring materials ablation (SCMA) is updated by implementing a coking process, in which a pyrolysis gas cokes within a char layer. The conservation equations for masses for resin, and coke, and energy are given. A coking rate equation is calculated by accounting for mass conservation of carbon deposited within...

For a re-entry capsule which carries out the atmospheric entry, the ablator is used for the thermal protection material. In order to design the heat protection system of the capsule, it is necessary to understand the thermal behavior by heating tests and numerical simulations. In this study, the ablation analysis program was developed to simulate t...

A space vehicle which undergoes the atmospheric re-entry or a planetary entry needs the heat shield system to protect inner equipments against severe aerodynamic heating environments. Charring ablator is usually used for the heat shield system. In order to design the heat shield system, it is necessary to predict the thermal behavior under aerodyna...

The thermal characteristics of the low-density ablator are quantified by conducting the heating tests of materials in an arcjet wind tunnel. In the tests, test pieces of the ablator with a diameter of 40 mm and a length of 58 mm are put into arcjet flow. The arcjet wind tunnel is run for two sets of operational condition: a low heating condition fo...

This report presents a falsely abnormally elevated blood trough concentration (C(t)) of tacrolimus measured by antibody-conjugated magnetic immunoassay (ACMIA) methods in a renal transplant recipient. Because the C(t) of tacrolimus was 78.5 ng/mL at day 2 after a 52-year-old man underwent renal transplantation, we stopped the tacrolimus extended-re...

Though steroid withdrawal is done in many renal transplant recipients, some patients must restart steroids. Little report has investigated steroid withdrawal under pharmacodynamic monitoring. We assessed lymphocyte sensitivity to endogenous cortisol as a biomarker for determining the safety of steroid withdrawal in renal transplant patients, as we...

A carbon fiber reinforced plastic (CFRP) has been widely used as a heat shield material in aerospace community. The CFRP is very trusted as the heat shield material for a re-entry vehicle but a fuselage becomes heavy because the CFRP is the high density material. Very recently, Okuyama developed a new ultra light-weight CFRP that is called LATS. In...

A carbon fiber reinforced plastic (CFRP) has been widely used as a heat shield material in aerospace community. This CFRP will be pyrolyzed if material surface is heated, and a carbonized layer will be formed. The oxidation of carbonized CFRP in atmosphere was found to be divided into the rate-controlled oxidation region and the diffusion-controlle...

Using a cloth-layered carbon fiber reinforced plastic ablator with a specific gravity of about 1.5, the thermal response model of ablator is studied experimentally and numerically. Heating tests are carried out in the arcjet wind tunnel to quantify the thermal performance of ablator. In the tests, the surface temperatures and in-depth temperatures...

In the future, carbon fiber reinforced plastics (CFRPs) with high hydrogen gas barrier performance will find wide applications in all industrial hydrogen tanks that aim at weight reduction; the use of such materials will be preferred to the use of conventional metallic materials such as stainless steel or aluminum. The hydrogen gas barrier performa...

Coking phenomenon for low density carbon-phenolic ablative material exposed to aerodynamic heating is examined experimentally. The low density ablators with the nominal virgin density of 0.24g/cm3 are heated in arcjet wind tunnels with nitrogen and air as a test gas. The material in-depth density, in-depth and surface temperatures are measured. The...

The clinical efficacy of calcineurin inhibitors administered to renal transplant patients is considered to be a strong function of the area under the concentration time curve (AUC). Interestingly, monitoring timings of blood concentrations for two similar calcineurin inhibitors, cyclosporine (CYA; Neoral) and tacrolimus (TAC; Prograf) are different...

The target blood concentrations of tacrolimus (TAC) and cyclosporine (CYA) during continuous intravenous infusion (C(ss)) have been determined based on clinical experience. However, it is desirable that C(ss) should be set so that the AUC after intravenous infusion is equal to the AUC after oral administration (AUC(po)). Accordingly, we performed 1...

We performed 24-hour monitoring of cyclosporine (NEO) and tacrolimus (TAC) blood concentrations, evaluating pharmacokinetic parameters and characterizing circadian variations. The monitoring was performed in 10 instances on nine patients administered NEO and 12 out of 11 patients administered TAC. All cases were administered equally divided doses o...

We evaluated the relative clinical potency of cyclosporine (CyA) and tacrolimus (Tac) using pharmacodynamic and pharmacokinetic parameters of the drug to obtain the most suitable converting dose and target trough level. The relative pharmacodynamic potency was examined by the mean ratio of drug concentrations giving 50% inhibition of blastogenesis...

A CFRP (carbon fiber reinforced plastic) rotor blade of a rotorcraft that flies into sandstorms is eroded mechanically. Moreover, a rocket nozzle that consists of various carbon-based materials, such as CFRP, graphite and C/C (carbon/carbon composite) materials is impacted by particulates in combustion gas, and is eroded thermo-chemically and mecha...

Re-entry vehicles must possess a heat shield system, comprising an ablator, fibrous insulation, and so on, that can be attached to their body surface. Under atmospheric pressure, a high effective thermal conductivity value may be applied to the development of certain heat shield systems. The fibrous insulation employed by this design approach is th...

A lightweight heat shield material can be built by using a fully carbonized ablator. The ablator studied here is a completely carbonized two-layered Phenolic carbon fiber reinforced plastic (CFRP) prepared as thinly as possible. A virgin layer of the ablator is heavy compared with a carbonized layer. Therefore, the ablator of a conventional method...

The outer wall of reentry vehicles is covered with heat shield materials in order to protect them from severe aerodynamic heating. An ablator is a type of heat shield material effective for reentry vehicles. In particularly an ablator made of Phenolic carbon fiber-reinforced plastics (CFRP) is known to possess superior resistance against severe aer...

Direct synthesis of diphenyl carbonate (DPC) and aromatic polycarbonates (PC) by oxidative carbonylation of phenol and bisphenols with CO were studied using a palladium catalyst supported on hydrotalcite (HT). The catalyst (Pd(OAc)2/HT) combined with inorganic and organic redox co-catalysts, organic salts, and molecular sieves exhibited high cataly...

When the phenolic CFRP is heated in a nitrogen gas atmosphere, the phenolic resin is pyrolyzed and the gas containing oxygen is generated. This generated oxygen oxidized the phenolic CFRP. The oxidation of carbonized phenolic CFRP in the nitrogen gas atmosphere was found to be divided into the rate-controlled oxidation region and the diffusion-cont...

A computer code for charring ablation and thermal response analysis has been developed for simulation of one-dimensional transient thermal behavior of multi-layer stack of isotropic charring ablation materials used for re-entry capsules. Mathematical model of charring ablation including governing equations is summarized. Analytical solutions of sev...

This paper presents a series of experimental results on the passive augmentation technique of boiling heat transfer by supplying solid particles in liquid. A cylindrical heater 0.88 mm in diameter is placed in saturated water, in which a lot of mobile particles exist, and the nucleate and film boiling heat transfer characteristics are measured. Par...

HOPE (H-II Orbiting PlanE) is a re-entry vehicle launched by the H-II rocket. Its external thermal environment drastically changes according to the various flight phases. The Thermal Control System (TCS) of HOPE has to keep all component temperatures within the required range under such external thermal conditions. Because of its launch and landing...