Bum-joon Kim

• Professor
• Professor (Associate) at osan univ.

Background Silkworm pupa (SWP) food anaphylaxis has been described frequently in Asian countries. However, false-positive reactions by skin pricks and serum IgE (sIgE) tests to the extract complicate diagnosis, requiring identification of clinically relevant major allergens. Objectives In this study, we characterized a novel SWP allergen, Bomb m 4...

In this study, the creep deformation of ferritic/martensitic 9Cr-1Mo (Grade T91) steel boiler tubes that occurs during the operation of thermal power plants is studied using crystal elasto-viscoplasticity finite element analysis (CEV-FEA). The material properties and creep behaviour of Grade T91 were obtained through experimentation and computation...

Purpose: Specific IgG4 (sIgG4) increases with allergen specific immunotherapy and may reflect a state of immune tolerance in food allergy. While ImmunoCAP® has been widely used to measure sIgG4 to a single allergen, PROTIA™ Specific IgG4® has been designed as a multiplex assay for measuring sIgG4. This study sought to validate this assay in compar...

Presently, countries are trying to increase their energy efficiency. Therefore, the operating temperatures of very high temperature reactor (VHTR) and high temperature gas-cooled reactor (HTGR) are increasing in order to increase overall efficiency. A metallic material’s intrinsic creep property is a limitation in this scenario. Inconel 617 alloy i...

As the traditional uniaxial test requires substantial amount of cost and material usage for specimen, it is hardly applied to the direct diagnosis of structural integrity of in-service facilities. Small punch (SP) test has been, alternatively, introduced to procure material properties because SP test just needs a slice of material (10 × 10 × 0.5 mm...

The whitefly Bemisia tabaci is a very destructive pest. B. tabaci is composed of various morphologically undistinguishable biotypes, among which biotypes B and Q, in particular, draw attention because of their wide distribution in Korea and differential potentials for insecticide resistance development. To develop a biotype-specific protein marker...

Small punch creep test (SPCT) has strong advantages in practice compared with traditional uniaxial creep test because a small sheet specimen (10 × 10 × 0.5 mm) can be obtained from in-service facilities or mechanical components without damage. In this paper, a novel investigation is proposed to directly interpret SPCT results in consideration of Ch...

Generally, the merits of pure electric vehicle(EV) are a low level of environmental pollution, noise, high efficiency, availability of multiple energy resources, and ability of energy feedback, while the driving performance is bad from the viewpoint of acceleration, maximum speed and grade ability. Therefore to improve these disadvantages is a hot...

The small punch creep test method was developed to complement the demerits of the existing uniaxial creep test method. A 10x10x0.5mm thin-plate specimen was used in the test, which could help save specimens and testing time. However, theories on the mechanism and significance of the small punch creep test have not been established clearly yet, and...

The molding process can be divided into five separate steps: plastification, injection, holding, cooling, and finally ejection. In the plastic injection molding, the effect factor such as mold temperature, injection speed, packing pressure and inhomogeneous cooling under packing process affects both the article dimension and physical characteristic...

Although specific IgE to the storage mite Acarus siro is often detected, there are no detailed studies on IgE reactivity to A. siro in Korea. This study was undertaken to investigate the cross-reactivity to the mite species Dermatophagoides pteronyssinus, Dermatophagoides farinae, Tyrophagus putrescentiae, and A. siro in Korean mite allergic patien...

The relationship between the small-punch creep test and the conventional creep test was investigated experimentally using a method similar to that of the Monkman-Grant relationship. Uniaxial and small-punch creep rupture tests were carried out on 9Cr-2W ferritic steel (Commercial Grade 92 steel: X10CrWMoVNb 9-2) at elevated temperatures. From the r...

In this work, we have studied the influence of microstructural changes of precipitates such as intermetallic sigma (ó) phase and M23C6 carbides on the creep behavior of the high temperature aged AISI 316L stainless steel by nondestructive small punch test and ultrasonic test. Small punch (SP) creep tests were also performed to determine the creep r...

An elastic network model (ENM), usually Cα coarse-grained one, has been widely used to study protein dynamics as an alternative to classical molecular dynamics simulation. This simple approach dramatically saves the computational cost, but sometimes fails to describe a feasible conformational change due to unrealistically excessive spring connectio...

Threshold stress intensity factor (ΔK th ), one of the important parameters in plant design, is the value below which fatigue crack growth becomes unrecognizably slow. Although studies on the each effect of various factors such as temperature, frequency, stress ratio, oxidation and grain size on the ΔK th have been reported widely, only few researc...

A low powered hydrogen gas sensor of the FET (field-effect transistor) structure was designed, fabricated and characterized for self-compensation to outer environments. The dual-gate FET hydrogen sensor was integrated with a micro-heater and two Pt-gate FETs; a sensing device for hydrogen detection, and a reference device as an electrical compensat...

In this work, we examined the influence of microstructural changes, such as an intermetallic sigma (σ) phase, on the fatigue behavior of high-temperature aged AISI 316L stainless steel. Nondestructive ultrasonic test and fatigue crack growth tests were performed to determine the threshold stress intensity factor of these artificially aged specimens...

9-12% Cr steels have been used in thermal power plants which repeat start and stop operations. Major factors of fatigue life are temperature, frequency, stress ratio, holding time, microstructure, and environment. Normally, fatigue life decreases at high temperature, low frequency, high stress ratio, and long holding time conditions. A Mod.9Cr-lMo...

Ever since its inception, a popular DNA motif called the cross tile has been recognized to self-assemble into addressable 2D templates consisting of periodic square cavities. Although this may be conceptually correct, in reality certain types of cross tiles can only form planar lattices if adjacent tiles are designed to bind in a corrugated manner,...

In this work, SP creep tests were applied to the Inconel 617 alloy and its weldment, which is one of the candidate materials for future advanced fossil power plant. To find the creep characteristics of the weakest local part in Inconel 617 alloy weldment, test specimens of thin squares (10 10 0.5mm) were machined at three different locations: weld...

Small punch creep testing has received attention due to the convenience of using smaller specimens than those of conventional uniaxial creep tests, which enables creep testing on developing or currently operational components. However, precedent studies have shown that it is necessary to consider friction between the punch and specimen when computi...

In this study, micro gas sensors for ammonia gas were prepared by adopting MEMS technology and using a sol-gel process. Three types of sensors were prepared via different synthesis routes starting with W sal and Ru sol mixture. This mixture was deposited on a MEMS platform and the platform was subsegueny heated to a temperature of 350 degrees C. Th...

The radioprotective effect of geraniin, a tannin compound isolated from Nymphaea tetragona Georgi var. (Nymphaeaceae), against γ-radiation-induced damage was investigated in Chinese hamster lung fibroblast (V79-4) cells. Geraniin recovered cell viability detected by MTT test and colony formation assay, which was compromised by γ-radiation, and redu...

The ethylacetate fraction of Empetrum nigrum var. japonicum (ENE) was shown to reduce intracellular reactive oxygen species (ROS) generated by γ-radiation and activate antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and gluthathion peroxidase (GPx). ENE protected cells against radiation-induced cellular DNA damage, membrane...

The protective effect of KIOM-4, a mixture of plant extracts, was examined against streptozotocin (STZ)-induced mitochondrial oxidative stress in rat pancreatic β-cells (RINm5F). KIOM-4 scavenged superoxide and hydroxyl radicals generated by xanthine/xanthine oxidase and Fenton reaction (FeSO(4)/H(2)O(2)), respectively, in a cell-free chemical syst...

The small punch creep (SPC) test has recently received much attention as a new alternative to the conventional umaxial creep test because it needs only a immature sized specimen directly detached from an operating system or component without any serious sampling damages However, it is difficult to obtain the equivalent umaxial creep data directly f...

In this study, the relationship between the creep ductility and rupture life of 9Cr-1.5Mo steel with boron addition at 600°C was investigated by small punch (SP) creep test from the viewpoint of the modified Monkman-Grant relation. The amount of boron addition ranged from 0.0076wt% to 0.0196 wt%. The general concept of Monkman-Grant ductility for u...

This study investigated the cytoprotective effect of butin, a flavonoid, on hydrogen peroxide (H(2)O(2))-induced mitochondrial dysfunction. Electron spin resonance (ESR) spectrometry revealed butin's significant scavenging effects on superoxide radicals and hydroxyl radicals. When H(2)O(2) was used to induce an increase in mitochondrial reactive ox...

In this study, the Single-Walled Carbon nanotubes (SWNT) reinforced copper matrix nanocomposite was investigated for the mechanical properties. To obtain the uniform composition of nanocomposite specimens, the mixing processes were conducted by ultrasonicating the SWNT and copper powders in ethanol. The process of coating the SWNT with nickel makes...

This paper investigates the influence of aging time on creep properties via a small punch creep test and evaluates the microstructural change of P122 steel at 600 degrees C. The area fraction of precipitates was quantitatively analyzed to identify the relationship between the creep rupture life and precipitates. The coarsening behavior of precipita...

In this paper, to improve the poor wettability between the Carbon nanotubes (CNTs) and metal matrix, the mechanical alloying (MA) technique by the ball milling method was employed. Also, the CNTs were pre-coated to improve the agglomeration of the CNTs with copper powder. The main aim of this work is the fabrication of Cu-CNT nanocomposite powder u...

We here demonstrate the use of multi-walled carbon nanotubes (MWNTs) as a platform matrix for immunoassay using horseradish peroxidase (HRP) as a model protein. After immobilization of HRP onto MWNTs using 1-pyrenebutanoic acid, succinimidyl ester as a cross-linker, the protein-loading capacity of MWNTs was determined by measuring the enzyme activi...

Mechanical, electrical and thermal properties of nickel-coated single-walled carbon nanotube (SWNT) reinforced copper matrix composites were investigated. The composites were fabricated by means of a powder metallurgy process, which consists of mixing nickel-coated carbon nanotubes with copper powders followed by hot-pressing. A homogeneous mixture...

In the previous study, residual life time of creep damaged 9Cr-2W steel specimens were evaluated using attenuation of ultrasound and area fraction of precipitates. Since attenuation coefficients and area fraction of precipitates were increased as increasing their aging time. However, cause of increasing attenuation of ultrasound is not only increas...

For thick-section components such as headers and pipes of the power plants, high creep rupture strength and oxidation resistance are required. It is known that the addition of boron can improve the creep strength and oxidation resistance through the stabilization of M23C6 carbides in the vicinity of prior austenite grain boundaries. In this study,...

In the present study, the characteristics of creep damage in P92 alloy were investigated via nondestructive evaluation. Generally, as the hold time of a static load increases, the degradation of the material becomes more severe along with a reduction of service life. Therefore, in power plants, the reduction of creep-fatigue strength and the creep-...

The aim of this research is to evaluate the local creep damage of various microstructures such as coarse grained heat affected zone (CGHAZ), fine grained heat affected zone (FGHAZ), intercritical heat affected zone (ICHAZ) known as Type IV region, weld metal, and base metal of P92(9Cr-2W) steel weldment by small punch (SP) creep test at 600°C. Also...

Creep rupture and creep crack growth of the heat-affected zones (HAZs) of P92(9Cr–2W) steel weldment are compared with those of base metal. From metallurgical investigation, creep cavities were observed at intercritical HAZs. The strain rate of the HAZ was faster than that of the base metal. The crack growth rate of the HAZ was faster than that of...

9Cr-2W steel is used as structural materials of high temperature and pressure components in power plants. These components can be degraded as increasing their operation time. Since isothermal aged 9Cr-2W steel is subject to cavities or precipitates between grain boundaries, it is one of the major causes of early breakage of these components. Theref...

In the present study, the application of nondestructive evaluation to determine the characteristics of creep damage in P92 alloy was investigated. Generally, as the hold time of static load increases, the degradation of material becomes more severe with the reduction of service life. Therefore, the creep-fatigue strength and life of high-pressure v...

The antioxidant properties of rhapontigenin and rhaponticin isolated from Rheum undulatum were investigated. Rhapontigenin was found to scavenge intracellular reactive oxygen species (ROS), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and hydrogen peroxide (H2O2). The radical scavenging effect of rhapontigenin was more effective than rhapontic...

Carbon nanotubes have received considerable attention because of their excellent electrical and mechanical properties. In this study, carbon nanotube - copper nanocomposites with homogeneously dispersed nanotubes within the copper matrix have been fabricated by two different methods; a mechanical mixing process and a molecular-level mixing process,...

As the static loading period of a power plant increases, high temperature components such as main steam pipe and header are degraded and their creep lives are reduced. Generally, material degradation is influenced by nucleation, growth and coalescence of cavity, and precipitates formed during the long operating period of power plants. Creep strengt...

A numerical and experimental study has been performed to characterize the metal organic vapor phase epitaxy (MOVPE) growth of InGaN/GaN multi-quantum wells (MQW). One of the major objectives of the present study is to predict the optimal operating conditions that would be suitable for the fabrication of GaN-based light-emitting diodes (LED) using t...

Various hold periods in a cyclic wave of fatigue load were introduced to investigate loading frequency effects on crack growth behavior and microstructural damage. The crack growth path and microstructural damage characteristics at 600°C in tempered martensitic 9Cr-2W (P92) HAZ of welded steel were studied. Generally, low frequency effect with incr...

The effects of interfacial bonding on mechanical properties of single-walled carbon nanotube reinforced copper matrix nanocomposites were investigated. The nanocomposites were fabricated by means of a powder metallurgy process, which consists of mixing carbon nanotubes with matrix powder followed by hot-pressing. The mixing process was carried out...

The components of power plant such as main steam pipe and gas turbines are operated under static and cyclic load conditions. As the period of static load increases, the service life of these components decreases. Generally, the increase of cyclic load results in fatigue damage and the increase of static load period results in the metallurgical degr...

Creep strength and life of material is closely related with the microstructural characteristics. Components used under creep condition for long time are unable to maintain the stability of microstructure and experience degradation of material. From this viewpoint, it is necessary for safety and residual life of power plant to investigate creep prop...

Carbon nanotubes have received considerable attention because of their excellent mechanical properties. In this study, carbon nanotube - copper composites have been sintered by a mechanical mixing process. The interfacial bonding between nanotubes and the copper matrix was improved by coating nanotubes with nickel. Sintered pure copper samples were...

Fatigue strength and life of weldment at high temperature is very important for high temperature materials used in power plants. In this study, fatigue crack growth tests were performed at high temperature to examine the effect of microstructure on the crack growth resistance in P92 steel weldment. Microhardness of the weldment was also investigate...

In this study, the effect of microstructure on fatigue crack growth behavior of HAZ was investigated using newly developed P92 steel weldment. Fatigue crack growth rates of the fusion line and fusion line+2 mm in HAZ were found to be faster than that of welds or base metal, while fatigue crack growth rate of the fusion line+1 mm was the slowest. Th...

Fatigue strength and life of weldment at high temperature is very important for high temperature materials used in power plants. In this study, creep properties of weld metal, HAZ and base metal of P92 steel were evaluated by SP (small punch) creep test method. Fatigue crack growth behaviors in weld metal, HAZ and base metal of P92 steel were inves...