야전용 액체 연료개질 1 kW급 하이브리드 전원시스템 제어 연구

지현진,하상현,김영철,조성백,Ji, Hyun-Jin,Ha, Sang-Hyun,Kim, Young-Chul,Cho, Sung-Baek 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.4

A fuel cell/secondary battery hybrid power generation system could extend well beyond the efficiency and interoperability of the conventional diesel generator. The suggested power source system consists of 2.3 kW class PEMFC, 100 Ah lithium polymer battery, and two DC/DC converters by serial connection type. It was known that interoperability of sub-systems is the key factor for stable and optimal control of the hybrid power generation system. The modeling and simulation methods have been proposed to reduce the number of configurations and performance tests for components selection and select the optimized control condition of the power generation system. The control model for power source system is implemented based on the empirical formulation and carried out in the Matlab/Simulink environment. The results show that the simulation can be used to establish the algorism of prototype and increase the durability of the power source system.

열전지의 열원 연소에 따른 전류집전체 열변형에 관한 연구

지현진,김종명,김영철,조성백,Ji, Hyun-Jin,Kim, Jong-Myong,Kim, Young-Chul,Cho, Sung-Baek 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.4

Thermal batteries are primary batteries that use molten salts as an electrolyte and employ an internal pyrotechnic source to heat the battery stack to operating temperatures, typically between 450 and $550^{\circ}C$. The unit cell of thermal batteries consists of an anode, an electrolyte, a cathode, a heat pellet and a current collector. The heat source for such batteries is typically heat pellets based on $Fe/KClO_4$. The elevated temperature by combustion of heat pellet is supposed to cause a flatness non-uniformity, buckling, with a lateral extension diameter of current collector. This paper mainly focused on the combustion and buckling model of current collector to simulate the effect of heat source. Mechanical stresses in the current collector caused by thermal stress is a critical design consideration of thermal batteries because the internal short circuit could be occurred.

표면 습식 식각 및 열처리에 따른 GaN 단일 나노로드 소자의 전기적 특성변화

지현진,최재완,김규태,Ji, Hyun-Jin,Choi, Jae-Wan,Kim, Gyu-Tae 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.2

Even though nano-scale materials were very advantageous for various applications, there are still problems to be solved such as the stabilization of surface state and realization of low contact resistances between a semiconducting nanowire and electrodes in nano-electronics. It is well known that the effects of contacts barrier between nano-channel and metal electrodes were dominant in carrier transportation in individual nano-electronics. In this report, it was investigated the electrical properties of GaN nanorod devices after chemical etching and rapid thermal annealing for making good contacts. After KOH wet-etching of the contact area the devices showed better electrical performance compared with non-treated GaN individual devices but still didn't have linear voltage-current characteristics. The shape of voltage-current properties of GaN devices were improved remarkably after rapid thermal annealing as showing Ohmic behaviors with further bigger conductivities. Even though chemical etching of the nanorod surfaces could cause scattering of carriers, in here it was shown that the most important and dominant factor in carrier transport of nano-electronics was realization of low contact barrier between nano-channel and metal electrodes surely.

열전지 성능 시뮬레이션을 위한 기초 모델에 대한 연구

지현진,Ji, Hyun-Jin 한국군사과학기술학회 2008 한국군사과학기술학회지 Vol.11 No.1

This paper describes the basic model and simulation results of thermal battery. Voltage and thermal analysis is a critical part of thermal-battery design because of the need to maintain the inner temperature above the electrolyte melting point. Traditionally, battery design has depended on an empirical approach, in which prototype batteries are outfitted with thermocouples and the design of subsequent batteries is refined accordingly. We have developed the basic model that allows the design engineer to configure or modify a battery, quickly conduct a thermal analysis, and efficiently review the results. Based on performance tests, the thermal-battery model was established and the effect of design parameters on battery performance was analyzed.

청소년의 신체적 여가활동이 지닌 함의

지현진 ( Hyun Jin Ji ),김진희 ( Jin Hee Kim ) 경북대학교 사범대학부속 중등교욱연구소 2008 중등교육연구 Vol.56 No.2

여가스포츠 인프라 구축을 통한 도시 발전 전략 탐색

지현진(Hyun Jin Ji),김진희(Jin Hee Kim) 한국여가레크리에이션학회 2009 한국여가레크리에이션학회지 Vol.33 No.3

Local governments often utilize leisure-sport business to enhance their competitiveness with one another. The authors conducted a series of national and international case studies and were able to draw some guidelines. First, when constructing the infrastructure to host sport events, they must have a long-term view of the uses of the facilities, not satisfying themselves by stressing the honor of, or pride in, hosting the events and short-term revenue created by the first event. Second, they should throw their efforts to make the best use of the region`s natural and cultural heritages, since it is considered a more effective way of starting and accelerating regional development. Third, the cities or counties that are not big and affluent enough to host a large-scale sport event should think about hosting a single-item event or building an infrastructure for being a place suitable for training camp. Forth, they must shift their attention from elite sports to leisure sports for everyone and build an environment for not only sports but also culture, arts, and relaxation, in order to expand the scope of business and satisfy various demands of their people. Lastly, as long as the development is to help people live better, it must be friendly to the natural environment, in which people have to spend their lives.

청소년의 여가실태에 대한 종단분석

지현진(Hyun Jin Ji) 한국여가레크리에이션학회 2009 한국여가레크리에이션학회지 Vol.33 No.2

This study examined leisure time use, leisure patterns, leisure constraints, leisure satisfaction, and life satisfaction of Korean adolescents by using the data collected from the 4-year panel study. A total of 3,449 adolescent-parent panels were used for analyses including descriptive statistics and Paired Samples t-tests. The results showed that leisure time was reduced, and PC use, mass media use, hobby, and rest were most popular leisure activities, as promoted to the higher grades. As grades were higher, physical activities were reduced. Lack of leisure programs and facilities were the largest barriers for the study period. It reached the highest point of leisure satisfaction at the 3rd year of middle school. The middle school years showed higher life satisfaction than the high school years. It is supposed that there would be positive correlations among leisure time, leisure satisfaction and life satisfaction. The findings of the present study provide the significant implications that could help us understanding the adolescent group and propose the questions of future studies should deal with.

노년층 여가시간 소비의 재해석

지현진(Hyun Jin Ji) 한국여가레크리에이션학회 2007 한국여가레크리에이션학회지 Vol.31 No.1

This study examined the time use patterns (of leisure activities) of the Korean Elderly by using the data collected from the 2004 National Time Use Survey. A total of 7,754 time diaries which had been filled up by 3,877 elders for two days were used for various analyses including descriptive statistics, correlation analyses, cluster analysis, and ANOVA accompanied with the Scheffe`s tests. The results showed that the subjects could be clustered into 7 groups such as the passive, the learners, with friends, ever-greens, the prayers, brain survivors, and time-killers. The data also revealed that the clusters had different time use patterns in pursuing leisure. For example, the with friends group, who are mostly females with no spouse and income and little education, tended to pursue social meetings compared with the other clusters, while the ever greens group, who are mostly males with spouse and income and college education, tended to get engaged in outdoor sport activities. Overall, the findings of the present study provide the significant implications that could help us understanding the particular age group and the various levels of questions that future studies should deal with.

기혼여성의 여가스포츠 참여를 제약하는 요인들

지현진(Hyun Jin Ji) 한국여가레크리에이션학회 2006 한국여가레크리에이션학회지 Vol.30 No.3

The present study was aimed for exploring what discourages the married females in Korea from doing sport vs. non-sport leisure activities. A total of 239 married Korean females aged between 27 and 37 were surveyed with print questionnaires. The new leisure constraint scale developed by Ji and Lee(2003) was used in the study. The data were analyzed employing descriptive analysis, factor analysis, and t-tests. The average age of the subjects was 33, and most of them were educated up to college level. Almost a half of the subjects were full-time housewives and the other half were part-time or full-time employees. The constraint items were grouped into 6 factors: difficulty, self-consciousness, lack of time, facility inconvenience, physical barriers, and cognitive dissonance. The t-tests revealed that the subjects tended to stop sport activities due to the difficulty of the activity itself, lack of time, facility inconvenience, and cognitive dissonance more likely than in the case in which they stop non-sport activities. Also, the reasons the subjects were discouraged from starting such up-to-date sport activities as MTB, sky-diving, and wind-surfing were found to be lack of time and difficulty of the activity itself.

Bebq₂에 (pq)₂Ir(acac)가 선택 도핑된 2-파장 유기발광다이오드

김민영,지현진,장지근,Kim, Min-Young,Ji, Hyun-Jin,Jang, Ji-Geun 한국재료학회 2011 한국재료학회지 Vol.21 No.4

New organic light-emitting diodes with structure of indium-tin-oxide[ITO]/N,N'-diphenyl-N, N'-bis-[4-(phenyl-m-tolvlamino)-phenyl]-biphenyl-4,4'-diamine[DNTPD]/1,1-bis-(di-4-poly-aminophenyl) cyclohexane[TAPC]/bis(10-hydroxy-benzo(h)quinolinato)beryllium[Bebq2]/Bebq2:iridium(III)bis(2-phenylquinoline-N,C2')acetylacetonate[(pq)2Ir(acac)]/ET-137[electron transport material from SFC Co]/LiF/Al using the selective doping of 5%-(pq)2Ir(acac) in a single Bebq2 host in the two wavelength (green, orange) emitter formation were proposed and characterized. In the experiments, with a 300${\AA}$-thick undoped emitter of Bebq2, two kinds of devices with the doped emitter thicknesses of 20${\AA}$ and 40${\AA}$ in the Bebq2:(pq)2Ir(acac) were fabricated. The device with a 20${\AA}$-thick doped emitter is referred to as "D-1" and the device with a 4${\AA}$-thick doped emitter is referred to as "D-2". Under an applied voltage of 9V, the luminance of D-1 and D-2 were 7780 $cd/m^2$ and 6620 $cd/m^2$, respectively. The electroluminescent spectrum of each fabricated device showed peak emissions at the same two wavelengths: 508 nm and 596 nm. However, the relative intensity of 596 nm to 508 nm at those wavelengths was higher in the D-2 than in the D-1. The D-1 and D-2 devices showed maximum current efficiencies of 5.2 cd/A and 6.0 cd/A, and color coordinates of (0.31, 0.50) and (0.37, 0.48) on the Commission Internationale de I'Eclairage[CIE] chart, respectively.