Ki Young Kim

Samsung Advanced Institute of Technology, Usan-ri, Gyeonggi Province, South Korea

Are you Ki Young Kim?

Claim your profile

Publications (95)62.1 Total impact

  • Source
    JinHoon Jung, Ki Young Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: To reveal and classify site characteristics in densely populated areas in Chuncheon, Korea, Rayleigh-waves were recorded at 50 sites including four sites in the forest area using four 1-Hz velocity sensors and 24 4.5-Hz vertical geophones during the period of January 2011 to May 2013. Dispersion curves of the Rayleigh waves obtained by the extended spatial autocorrelation method were inverted to derive shear-wave velocity () models comprising 40 horizontal layers of 1-m thickness. Depths to weathered rocks (), shear wave velocities of these basement rocks (), average velocities of the overburden layer (), and the average velocity to a depth of 30 m (), were then derived from those models. The estimated values of , , , and for 46 sites at lower altitudes were in the ranges of 5 to 29 m, 404 to 561 m/s, 208 to 375 ms/s, and 226 to 583 m/s, respectively. According to the Korean building code for seismic design, the estimated indicates that the lower altitude areas in Chuncheon are classified as (very dense soil and soft rock) or (stiff soil). To determine adequate proxies for , we compared the computed values with land cover, lithology, topographic slope, and surface elevation at each of the measurement sites. Due to a weak correlation (r = 0.41) between and elevation, the best proxy of them, applications of this proxy to Chuncheon of a relatively small area seem to be limited.
    Geophysics and Geophysical Exploration. 01/2014; 17(1).
  • Chungho Kim, Abid Ali, Ki Young Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: To reveal shear-wave velocities () and site characterization of Wonju, Korea, Rayleigh waves were recorded at 78 sites of lower altitude using 12 to 24 4.5-Hz vertical geophones for 20 days during the period of February to September 2013. Dispersion curves of the Rayleigh waves obtained by the extended spatial autocorrelation method were inverted using the damped least-squares method to derive models. From these 1-D models, the average to a depth of 30 m (), of weathered rocks, depths to these basement rocks, and average of the overburden layer were derived to be , , , and , respectively, in the 95% confidence range. To determine adequate proxies for , we computed correlation coefficients of with topographic slope (r = 0.46) and elevation (r = 0.43). An empirical linear relationship is presented as a combination of individually estimated with weighting factors of 0.45, 0.45, and 0.1 for topographic slope, elevation, and mapped lithology, respectively. Due to a weak correlation between obtained from inversion of dispersion curves and the proxy-based estimation (r = 0.50), however, the relatively large error range should be considered for applications of this relationship.
    Geophysics and Geophysical Exploration. 01/2014; 17(1).
  • Near Surface Geophysics Asia Pacific Conference, Beijing, China 17-19 July 2013; 07/2013
  • 2013 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting; 07/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic resonance wireless power link including a non-coaxially aligned repeater resonator has been analyzed and designed for efficient mid-range wireless powering. Parametric study on the power transfer efficiency (PTE) for several meter distance range indoor powering has been made and optimization condition for maximum PTE have been obtained. The results are expected to be utilized for mid-range wireless powering in the presence of practical limitations of the resonator location.
    2013 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting; 07/2013
  • Source
    Iseul Park, Arim Han, Ki Young Kim
    Geophysics and Geophysical Exploration. 02/2013; 16(1).
  • Source
    Arim Han, Iseul Park, Ki Young Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: Continuous seismic observation of volcanic earthquakes related to migration of magma or gas, is one of the most important methods used to monitor active volcanoes. In this review paper, we introduce the characteristics of volcanic earthquakes and their classification based on locations of foci, waveforms, frequencies, lithology, and source mechanisms. We also present some examples of successful warnings of volcanic eruptions and the present status of some observations of volcanic earthquakes in Japan, the United States, Italy, and New Zealand.
    Geophysics and Geophysical Exploration. 01/2013; 16(4).
  • Source
    Won Young Yun, Sun-Cheon Park, Ki Young Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: To look into site characteristics of the Hwacheon borehole seismic station, we analyzed property of earthquake and microtremor recorded on surface and borehole seismometers. Acoording to analysis result of microtremor, the surface-to-borehole energy ratio was approximately 15 times greater during the daytime than during the nighttime, and the surface-to-borehole ratios of spectral amplitudes as frequency increases. For earthquake data, amplitude spectra and dominant frequency were computed using surface and borehole data. As a result, small earthquakes with short distance recorded on surface seismometer peaked at 8 Hz, 46 Hz. This result corresponds to resonance frequencies (7.4 Hz, 46 Hz) calculated by H/V spectral ratio. We confirmed amplification effect by site characteristics of overburden. Background noise level was approximately 20,000 times smaller at borehole seismic station than surface seismic station. These results provide strong evidence for the superior recording of earthquakes using borehole seismometers instead of surface seismometers.
    Geophysics and Geophysical Exploration. 01/2013; 16(4).
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recently, resonance phenomenon in wireless power transfer (WPT) is widely used to deliver power to a load over relatively large air gap via magnetic coupling. Since many reactive components in WPT system are contributed to the resonance phenomenon, there are many resonant frequencies. Theses resonant frequencies have different and distinguishing features. For this reason, the analysis of the resonant tank at various resonant frequencies is required to understand WPT system more easily. Therefore, in this paper, three resonant frequencies in series-series compensated WPT (SS-WPT) system are defined. And then, this paper is aiming to present the features of SS-WPT system in the major two of the three resonant frequencies. The analysis is supported with experimental results.
    ECCE Asia Downunder (ECCE Asia), 2013 IEEE; 01/2013
  • Source
    Taehyeon Jeon, Ki Young Kim, Namchul Woo
    [Show abstract] [Hide abstract]
    ABSTRACT: Shear-wave velocity () structures beneath two seismic stations, JJU and JJB on the flanks of the volcano Halla on Jeju island, Korea, were estimated by receiver-function inversion and H- stacking applied to 150 teleseismic events () recorded since 2007. waves converted at the Moho discontinuity does not appear clearly for northwesterly back-azimuths (, average ) at station JJU and southeasterly back-azimuths (, average ) at station JJB. This may be due to a gradual velocity increase at Moho or heterogeneity within the crust. The models derived by inversion of receiver functions indicate a distinct low velocity layer (; LVL) within the crust and a gradual increase in in the depth interval of 30 to 40 km. Within the radius of 18 km beneath station JJB, the LVL occurs at depths of 14 ~ 26 km and the 'Moho' () is at 34 km depth. Ten kilometers to the west, within the radius of 16 km beneath station JJU, both the LVL and the Moho are significantly shallower, at depths of 14 to 24 km and 30 km, respectively. H- analyses for stations JJU and JJB yield estimated crustal thickness of 29 and 33 km and ratios of 1.64 and 1.75, respectively. The lesser ratio was derived for rocks nearest to th peak of the volcano.
    Geophysics and Geophysical Exploration. 01/2013; 16(1).
  • [Show abstract] [Hide abstract]
    ABSTRACT: Practical magnetic resonance wireless power transfer (WPT) system is presented. High-efficient power amplifier (PA) and adaptive tracking modules are combined with optimized wireless power links to propose mid-range wireless powering application scenarios in home-environments.
    Consumer Electronics (ICCE), 2013 IEEE International Conference on; 01/2013
  • Source
    Won Young Yun, Sun-Cheon Park, Ki Young Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: We estimated near-surface shear-wave velocity () at the Hwacheon seismic station using a geologic log of a well, microtremors recorded during a period of 56 days, and records of three teleseismic events (). The vs of the 10-m thick soil layer (= 296 m/s) was determined from horizontal-to-vertical spectral ratios of microtremors recorded at the surface. The average (= 1,309 m/s) from the surface to the 96-m depth of a borehole sensor, was computed using spectral coherence analyses of data recorded by surface- and borehole-sensors for the three teleseismic events. Using these calculated values of and , the computed bedrock is 2,150 m/s and the time-averaged to a 30-m depth is 696 m/s. Accordingly the Hwacheon seismic station is regarded as a relatively good site. The deduced near-surface can be used for further quantitative evaluation of site amplification and earthquake hazard.
    Geophysics and Geophysical Exploration. 01/2013; 16(3).
  • Source
    Yeong Hwan Park, Ki Young Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: On and near the 23-m high earthen Cheongcheon dam in Boryeong City, Korea, short seismic refraction and surface-wave profiles were conducted using a 5-kg sledgehammer. From vertical and horizontal components of the seismic waves, near-surface P-wave velocities () and S-wave velocities () were derived by inverting first-arrival refraction times and dispersion curves of Rayleigh waves. Average and for the Jurassic sedimentary basement were determined to be 1650 and 950 m/s at a depth of 30 m directly beneath the dam and 1650 m/s and 940 m/s at a depth of 10 m at the toe of the dam, respectively. The dynamic Poisson's ratio for these strata were therefore in the range of 0.24 to 0.25, which is consistent with ratios for consolidated sedimentary strata. Near a 45-m borehole 152 m downstream from the dam crest, an SH tomogram indicates a refraction boundary with an average of 870 m/s at depths of 10 ~ 12 m. At this site, the overburden comprises the upper layer with relatively constant and around 500 and 200 m/s, respectively, and the lower layer in which both and increase with depth almost linearly. The dynamic Poisson's ratios for the overburden were in the range of 0.30 to 0.43.
    Geophysics and Geophysical Exploration. 01/2013; 16(3).
  • [Show abstract] [Hide abstract]
    ABSTRACT: The charging characteristics of non-radiative wireless power link (NWPL) have been well unknown. This paper shows that series-series (SS) compensated NWPL system behaves as a constant current power supply when the inverter operates at the resonant frequency of self-inductance and resonant capacitors.
    Circuits and Systems (ISCAS), 2013 IEEE International Symposium on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: Efficient wireless charging control scheme for powering a single device unit is presented. The proposed scheme uses in-band communication and analog circuits to control the clock signal lengths. Since it can generate the control data packets without MCU, it is easy to implement a one-chip of the RX parts. We have verified the performance of the in-band communication for the WPT system while a mobile device is in charging.
    Consumer Electronics (ICCE), 2013 IEEE International Conference on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Kidneys previously exposed to ischemia and reperfusion (I/R), pre-conditioned by I/R, are less susceptible to subsequent I/R injury. Here, we investigated the role for protein kinase B (Akt) survival signaling pathways including anti-apoptosis pathways in the reduced susceptibility of I/R-pre-conditioned kidneys.METHODS: Mice were exposed to either a single I/R pre-conditioning event (SIRPC, 30 min of bilateral renal ischemia followed by 8 days of reperfusion) or sham-operation (non-SIRPC) and then subjected to either 30 min of bilateral renal ischemia or sham-operation (sham). Some of the mice received intra-peritoneal administrations of wortmannin, which is an inhibitor of phosphatidylinositol-3 kinase, PI3K.RESULTS: Thirty minutes of bilateral renal ischemia in non-SIRPC mice induced a dramatic increase in plasma creatinine (PCr) levels, but this was not observed in the SIRPC mouse. Consistent with the PCr results, tubular damage and apoptotic tubular cell death were more severe in the non-SIRPC mouse kidney than in the SIRPC mice. SIRPC increased the levels of phosphorylated-Akt and -Bad expression as well as the ratio of Bcl-2 to Bax expression in the kidney. I/R resulted in greater increases of phosphorylated-Akt and -Bad, Bcl-xL and Bcl-2, but a lower level of increase of Bax, in the SIRPC mouse kidneys than those in the non-SIRPC-mouse kidneys. Treatment with wortmannin during the SIRPC period inhibited SIRPC-induced increase in phosphorylated-Akt and -Bad expressions and eliminated tolerance of SIRPC mice kidneys to I/R insult.CONCLUSION: Ischemic pre-conditioning confers renal resistance to I/R-induced apoptosis via activation of the Akt signal pathway.
    Nephrology Dialysis Transplantation 05/2012; · 3.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we obtain transmission cross section (TCS) for the multiple resonant apertures using full wave simulation. The equivalent magnetic current element of the structure is put to explain the resonant transmission effectively. Finally we solve the self conductance and mutual conductances for four different structures. The conductances are quite similar to the resistances of multiple dipoles.
    Antennas and Propagation Society International Symposium (APSURSI), 2012 IEEE; 01/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: An automated frequency tracking system for an efficient mid-range wireless power transfer is realized based on an analysis of magnetic resonance wireless power link consisting of high-quality factor transmitting and receiving resonators. The proposed automatic adaptive frequency tracking system is designed to maintain a power transfer efficiency of higher than 70% for any transfer mid-range distance by directly monitoring the link efficiency using wireless communication. The advantage of the proposed system over other frequency tracking schemes is that the efficiencies of the wireless power link and power amplifier can be considered in the frequency tracking algorithm. The proposed system has been successfully demonstrated with an operation of normal digital LED TV.
    Microwave Conference (EuMC), 2012 42nd European; 01/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: The wireless power receiver with load modulator for inband communication is proposed. The MOS transistor is used for the load modulator of inband communication and the proposed wireless power receiver is implemented with 0.35μm 2P4M BCDMOS technology. The efficiency of the wireless power receiver is obtained as high as 80% for ~3W pickup at 13.56 MHz of transfer frequency. We have verified the performance of the inband communication for the WPT system while a mobile device is in charging.
    Microwave Conference (EuMC), 2012 42nd European; 01/2012
  • Nam Yoon Kim, Ki Young Kim, Chang‐Woo Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: An automated frequency tracking system is implemented for an efficient mid‐range magnetic resonance wireless power transfer based on an analysis of a wireless power link consisting of transmitting and receiving resonators placed in a strong coupling region.The proposed tracking system is designed to maintain a power transfer efficiency of more than 70% for any transfer distance range by directly monitoring the efficiency via out‐band communication. The advantage of the proposed system over other frequency tracking schemes is that the performance of the resonators and power amplifier can be applied to the tracking algorithm. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1423–1426, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26858
    Microwave and Optical Technology Letters 01/2012; 54(6). · 0.59 Impact Factor

Publication Stats

467 Citations
62.10 Total Impact Points

Institutions

  • 2012
    • Samsung Advanced Institute of Technology
      Usan-ri, Gyeonggi Province, South Korea
  • 2011
    • Sejong University
      Sŏul, Seoul, South Korea
  • 2010
    • Korea Advanced Institute of Science and Technology
      • Department of Electrical Engineering
      Sŏul, Seoul, South Korea
    • Korea Institute of Science and Technology
      Sŏul, Seoul, South Korea
  • 2009
    • Hanyang University
      • Department of Industrial Engineering
      Sŏul, Seoul, South Korea
    • National Institute of Crop Science
      Sŏngnam, Gyeonggi Province, South Korea
  • 2007–2009
    • Northwestern University
      • Department of Electrical Engineering and Computer Science
      Evanston, IL, United States
  • 2004–2009
    • Chung-Ang University
      • School of Mechanical Engineering
      Seoul, Seoul, South Korea
  • 2008
    • Union Corporation, South Korea
      Sŏul, Seoul, South Korea
  • 2003–2008
    • Daejeon University
      Daiden, Daejeon, South Korea
    • Sungkyunkwan University
      • Department of Chemical Engineering
      Sŏul, Seoul, South Korea
  • 2003–2007
    • Dongseo University
      • Department of International Logistics
      Pusan, Busan, South Korea
  • 2006
    • Electronics and Telecommunications Research Institute
      Sŏul, Seoul, South Korea
    • Information and Communications University
      Daiden, Daejeon, South Korea
  • 2000–2006
    • Kyungpook National University
      • • School of Computer Science and Engineering
      • • Department of Electrical Engineering
      Taegu, Daegu, South Korea
  • 1997–1999
    • Pusan National University
      • Department of Industrial Engineering
      Pusan, Busan, South Korea