Ultra - Soft Magnetic Properties in Nanocrystalline Fe81B₁₁Nb7Cu₁ Alloy

Heebok Lee,Kyeong-Jae Lee,Yong-Kook Kim,Sung-Ho Yoon,Taik-Kee Kim,Seong-Cho Yu 한국자기학회 2000 Journal of Magnetics Vol.5 No.3

The extremely soft magnetic behaviors in the nanocrystalline Fe_(81)B₁₁Nb_7Cu₁ alloy annealed at 450 ℃ and 550 ℃ for 1 hour in a vacuum were investigated by means of the magnetoimpedance (MI) effect and the incremental permeability. Because the MI effect can be obtained only in ultra-soft magnetic materials, the improvement of magnetic softness by proper thermal treatment was carefully monitored by the MI effect for all annealed samples. The changes of the incremental permeability as a function of an external field were also measured to verify the magnetic softness along with the MI measurement.

Trends in Leopard Cat (Prionailurus bengalensis) Research through Co-word Analysis

Heebok Park,Anya Lim,Taeyoung Choi,Changwook Han,Yungchul Park 강원대학교 산림과학연구소 2018 Journal of Forest Science Vol.34 No.1

This study aims to explore the knowledge structure of the leopard cat (Prionailurus bengalensis) research during the period of 1952-2017. Data was collected from Google Scholar and Research Information Service System (RISS), and a total of 482 author keywords from 125 papers from peer-reviewed scholarly journals were retrieved. Co-word analysis was applied to examine patterns and trends in the leopard cat research by measuring the association strengths of the author keywords along with the descriptive analysis of the keywords. The result shows that the most commonly used keywords in leopard cat research were Felidae, Iriomte cat, and camera trap except for its English and scientific name, and camera traps became a frequent keyword since 2005. Co-word analysis also reveals that leopard cat research has been actively conducted in Southeast Asia in conjugation with studying other carnivores using the camera traps. Through the understanding of the patterns and trends, the finding of this study could provide an opportunity for the exploration of neglected areas in the leopard cat research and conservation.

Estimating Population Density of Leopard Cat (Prionailurus bengalensis) from Camera Traps in Maekdo Riparian Park, South Korea

Heebok Park,Anya Lim,Tae-Young Choi,Sang-Jin Lim,Yung-Chul Park 강원대학교 산림과학연구소 2017 Journal of Forest Science Vol.33 No.3

Although camera traps have been widely used to understand the abundance of wildlife in recent decades, the effort has been restricted to small sub-set of wildlife which can mark-and-recapture. The Random Encounter Model shows an alternative approach to estimate the absolute abundance from camera trap detection rate for any animals without the need for individual recognition. Our study aims to examine the feasibility and validity of the Random Encounter Model for the density estimation of endangered leopard cats (Prionailurus bengalensis) in Maekdo riparian park, Busan, South Korea. According to the model, the estimated leopard cat density was 1.76 km-2 (CI 95%, 0.74-3.49), which indicated 2.46 leopard cats in 1.4 km2 of our study area. This estimate was not statistically different from the previous leopard cat population count (2.33±0.58) in the same area. As follows, our research demonstrated the application and usefulness of the Random Encounter Model in density estimation of unmarked wildlife which helps to manage and protect the target species with a better understanding of their status.

Microbial Community Composition in the Marine Sediments of Jeju Island: Next-Generation Sequencing Surveys

( Heebok Choi ),( Hyeon Woo Koh ),( Hongik Kim ),( Jong Chan Chae ),( Soo Je Park ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.5

Marine sediments are a microbial biosphere with an unknown physiology, and the sediments harbor numerous distinct phylogenetic lineages of Bacteria and Archaea that are at present uncultured. In this study, the structure of the archaeal and bacterial communities was investigated in the surface and subsurface sediments of Jeju Island using a next-generation sequencing method. The microbial communities in the surface sediments were distinct from those in the subsurface sediments; the relative abundance of sequences for Thaumarchaeota, Actinobacteria, Bacteroides, Alphaproteobacteria, and Gammaproteobacteria were higher in the surface than subsurface sediments, whereas the sequences for Euryarchaeota, Acidobacteria, Firmicutes, and Deltaproteobacteria were relatively more abundant in the subsurface than surface sediments. This study presents detailed characterization of the spatial distribution of benthic microbial communities of Jeju Island and provides fundamental information on the potential interactions mediated by microorganisms with the different biogeochemical cycles in coastal sediments.

Magnetoimpedance Effect in Nanocrystalline Fe91.5-xZr7BxCu₁Al0.5 (x = 2, 4, 6, 8) Alloys

Heebok Lee,Yong-Kook Kim,Taik-Kee Kim,Chong-Oh Kim,Seong-Cho Yu 한국자기학회 2002 Journal of Magnetics Vol.7 No.1

The magnetoimpedance of Fe_(91.5-x)Zr_7B_xCu₁Al_(0.5) (x = 2, 4, 6, 8) alloys has been measured to investigate the influence of structural changes in the nanocrystallization process after thermal treatment. Annealing was performed at temperatures of 350℃, 450℃, and 550℃ for 1 hour in a vacuum. Ultra soft magnetic behavior was observed in the samples annealed at 550℃. The magnetoimpedance ratio and the longitudinal permeability ratio coincided with the softness of the magnetic properties of the thermally treated samples.

Super - giant Magneto - Impedance Effect of a LC - resonator Using a Glass - Coated Amorphous Microwire

Heebok Lee,Yong-Seok Kim,Seong-Cho Yu 한국자기학회 2002 Journal of Magnetics Vol.7 No.4

A new discovery of the super-giant magneto-impedance (SGMI) effect was found out in a LC-resonator consisted of a glass-coated amorphous Co_(83.2)B_(3.3)Si_(5.9)Mn_(7.6) microwire. The measurement was carried out at high frequency range from 100 ㎒ up to 1 ㎓ of an ac-current flowing along the wire and at varying axial dc-magnetic field in its range of ±120 Oe. The wires, about 16 ㎛ in diameter, were fabricated by a glass-coated melt spinning technique. The shape of the impedance curves plotted vs. a dc-field is changing dramatically with the frequency. The phase angle was also strongly dependent on this field. The external dc-magnetic field changes the circumferential permeability as well as the penetration depth, both in turn change the impedance of the sample. The drastic increments of SGMI at high frequency can be understood in terms of the LC-resonance phenomena. The sudden change of the phase angle, as large as 180°, evidenced the occurrence of the resonance at a given intensity of the external dc-field. The maximum ratio of SGMI reached in the experiment by precise tuning frequency equals 450,000% at the frequency of around 551.9075 ㎒.

Trends in Leopard Cat (Prionailurus bengalensis) Research through Co-word Analysis

Park, Heebok,Lim, Anya,Choi, Taeyoung,Han, Changwook,Park, Yungchul Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.1

This study aims to explore the knowledge structure of the leopard cat (Prionailurus bengalensis) research during the period of 1952-2017. Data was collected from Google Scholar and Research Information Service System (RISS), and a total of 482 author keywords from 125 papers from peer-reviewed scholarly journals were retrieved. Co-word analysis was applied to examine patterns and trends in the leopard cat research by measuring the association strengths of the author keywords along with the descriptive analysis of the keywords. The result shows that the most commonly used keywords in leopard cat research were Felidae, Iriomte cat, and camera trap except for its English and scientific name, and camera traps became a frequent keyword since 2005. Co-word analysis also reveals that leopard cat research has been actively conducted in Southeast Asia in conjugation with studying other carnivores using the camera traps. Through the understanding of the patterns and trends, the finding of this study could provide an opportunity for the exploration of neglected areas in the leopard cat research and conservation.

고라니(Hydropotes inermis)의 로드킬(Roadkill) 방지 울타리 적정 높이 평가

박희복 ( Heebok Park ),우동걸 ( Donggul Woo ),송의근 ( Eui-geun Song ),임정은 ( Anya Lim ),이배근 ( Bae-keun Lee ),장지덕 ( Ji-deok Jang ),박태진 ( Tae-jin Park ),최태영 ( Tae-young Choi ) 한국환경영향평가학회 2018 환경영향평가 Vol.27 No.2

이 연구는 국내 로드킬(Roadkill) 피해 발생건수가 가장 높은 야생동물인 고라니(Hydropotes inermis)를 대상으로 로드킬 예방에 필요한 저감시설인 유도울타리의 적정 높이 기준을 마련하기 위해 이루어졌다. 이를 위해 국외 사슴류 흰꼬리사슴(Odocoileus virginianus)의 울타리 월장 측정 연구사례와 비화학적 포획 방법을 검토하여 국립생태원 사슴생태원에서 관리하는 고라니 27마리를 대상으로 울타리 월장 실패율 측정 방법에 적용하였다. 펜스(test fence) 높이 0.5m에서부터 단계별 10cm씩 높여가며 넘을 수 없는 높이를 검증하였다. 그 결과 1.5m로 설치할 경우 고라니의 침입을 96.7% 차단 가능하고, 1.8m 높이에서는 100% 차단하는 것으로 확인되었다. 이 연구결과를 토대로 향후 환경부 「생태통로 설치 및 관리지침」개정 시 유도울타리 적정 높이 기준 설정에 의미 있는 자료로 활용될 것으로 기대된다. Our study aims to provide a guideline of deer-proof fence heights to prevent roadkill of water deer (Hydropotes inermis), the most frequently killed by a vehicle collision, in South Korea. With 27 water deer in deer ecology center of the National Institute of Ecology, we measured the ability of water deer to jump gradually higher fences from 0.5cm by 10cm until the deterrence rate reached 100%. Our result revealed that the deterrence rate became 96.7% at the fence height of 1.5m and the rate reached 100% at the 1.8m. We believe that our result provides the fundamental information to prepare a standard of deer-proof fence height. This evidence-based standard will contribute to improving the guideline for wildlife crossing construction and management, established by Ministry of Environment Korea.

Temperature dependence of magnetoimpedance effect in amorphous CO?? Fe₄NiB?? Si? ribbon

Lee, Heebok,Cho, W.S,Kim, C.O,Kim, T.K,Kim, Y.K 公州大學校 基礎科學硏究所 1998 自然科學硏究 Vol.7 No.-

The temperature dependence of the magnetoimpedance (MI) effect is important both for scientific study and for thermal stability of MI sensors. We have performed the measurement of MI effect in amorphous Co66Fe4 NiB14Si15 (Metglas 2714A) ribbon from a cryogenic chamber where the temperature of the sample can vary from 10 to 300 K. The ac current was fixed at 10 mA for all measured frequencies ranging from 100 kHz to 10 MHz. The magncioimpedancc ratio (MIR) was revealed the drastic increment as a function of MIR(T)=MIR(O)exp(cT2), where c is a constant. The measured MIR values at room temperature are usually 2-3 times larger than the data measured at 10 K for all measured frequencies. However, the shapes of the MIR curves are remained. This result shows the potential application of the MI effect for a temperature sensor.

시험 DFSS기법을 이용한 릴레이의 고장인자 영향도 분석

이희복(Heebok Lee),위신환(Shinhwan Wi),엄학용(Hakyong Eom),성기우(Kiwoo Sung),이용(Yong Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

Failure factors of the automotive relay are operating voltage, load voltage, temperature and chattering count. In order to analyze effects of failure factors for the relay, effects of them are solved through DFSS method. In this study, the effect of failure factors is analyzed under the same load. The final results are as follows; ⅰ) Experiment is designed by L? tables of orthogonal arrays. ⅱ) failure factors of four types are used as control factors. And 3 levels are used. ⅲ) The influence of failure factors is interpreted in the following orders; (1. Chattering count 2. Load voltage. 3. Temperature. 4. Operating voltage.) ⅳ) finally for these reason, influence of failure factors is analyzed and verified.