• 한국추진공학회지
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• 제26권1호
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• pp.28-37
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• 2022

밀폐용기(Closed Bomb)시험을 통해 고압에서 작동하는 고체 추진제의 연소속도를 추정하는 방법을 연구하였다. CEA를 이용하여 연소가스의 조성을 계산였으며 밀폐용기 내부의 고온, 고압의 환경을 묘사하기 위해 Noble-Abel 상태방정식을 적용하였다. 분자의 부피를 고려한 분자 간의 충돌을 묘사하는 인자인 Covolume을 분자의 LJ potential을 이용하여 모델링하였다. 또한 추진제의 부피 변화율을 고려하기 위해 3차 형상함수(Cubic form function)를 적용하였다. 각 모델을 사용하여 고압용기에서 측정된 5개의 압력-시간 선도로부터 연소속도를 계산하고 이를 BRLCB 결과와 비교 검증하였다. 각 실험에서 약 6% 이내의 최대 오차를 갖는 연소속도를 추정함으로써 초고압 환경에서의 연소속도 추정 방법을 정립하였다.

• 대한전자공학회논문지
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• 제23권1호
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• pp.1-9
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• 1986

This is the third part of the four-part paper describing the development of a packet-switched computer communication network named the KORNET. In this paper we describe the design and implementation of the X.25 protocol connecting packet mode data terminal equipments(PDTE's) with data circuit terminating equipments(DCE's). In the KORNET, the X.25 protocol has been implemented on the line processing module-A(LPMA) of the network node processor(NNP). In the implementation of X.25, we have divided the software module according to the service function, and have determined the the rules that interact between the modules. Each layer protocol has been developed using the technique of the finite state machine. Before the actual coding of softwares, we hafve used formal software development tools based on the specification and description language (SDL) and program design languate (PDL) recommended by the CCITT. In addition, for the efficient operation of the X.25 protocol system we have analyzed the system performance and the service scheduling method of each module. The results will also be given.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.455-458
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• 2008

본 연구는 기계설비 전문건설업체를 대상으로 기능인력운영의 문제점을 분석하고 개선방안을 제시하고자 실시하였다. 이를 위하여 18개 기계설비 전문건설업체의 경영자/작업반장 및 일반건설업체 현장관리자를 사례대상으로 선정한후 직 하도급별 문제점을 설문 조사하였으며, 조사된 문제점을 바탕으로 기능인력운영 실태를 분석한 후 개선방안을 도출하였다. 상기와 같은 목적과 방법에 따라 수행한 본 연구의 결론을 요약하면 다음과 같다. 첫째, 현장에서의 작인반장의 역할은 도급제 근로자를 관리운영 하는 책임자이지만 원도급자와의 종속적인 관계로 인한 인력관리 권한축소로 인해 기능인력관리에 어려움이 있다고 분석되었다. 둘째, 효율적인 기능인력운영을 위해 작업반장의 현장대리인화 또는 연봉제로 고용된 작업반장을 통한 인력관리가 기능인력운영상의 개선방안으로 도출되었다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.415-420
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• 2005

This paper presents the two lossless auxiliary inductors-assisted voltage source type half bridge (single ended push pull: SEPP) series resonant high frequency inverter for induction heated king roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation for wide its output power regulation ranges and load variations under its constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation characteristics-based on the high frequency PDM strategy. The experimental operating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimental ones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliance implemented here is proved from the practical point of view.

• 한국한의학연구원논문집
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• 제12권1호
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• pp.13-22
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• 2006

Background and Aims: Herbal drugs and traditional medicines have lately attracted considerable attention by global pharmaceutical corporations because the conventional chemical drugs didn't work well for many chronic diseases or intractable diseases. The government of Korea is also supporting to develop the new drug which is high value added product, and the natural medicine including herbal medicine(or Traditional Korean Medicine) have a significant presence in this field. non-clinical pharmacology/toxicology study and clinical trial are the two major criteria which estimate efficacy and safety for registration of new drugs. All of the pharmaceutical companies producing herbal medicine and the academic and the academic world of Tradition Korean Medicine have the will to develop new herbal drugs, but there are obstacles that they have neither experience nor guideline about clinical trial. Therefore for developing new herbal drugs, it is necessary to research the present conditions and comprehensive systems about clinical trial in Northeast Asian countries China, Taiwan and Japan because they have the common background with Korea in traditional medicine fields. Methods : The present state of clinical trial for herbal medicine in Korea was investigated. And then, those in China, Taiwan, Japan was also investigated. Results and conclusions : There are significant differences among 4 Southeast Asian countries Korea, China, Taiwan and Japan each in present condition, purpose, involved comprehensive system including legislation, and actual operation of clinical trial for traditional medicine.

• 대한기계학회논문집
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• 제15권2호
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• pp.463-477
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• 1991

This study proposed a new method to design a robot manipulator control system capable of tracking the trajectories of joint angles in a reasonable accuracy to cover with actual situation of varying payload, uncertain parameters, and time delay. The direct adaptive model following control method has been used to improve existing industrial robot manipulator control system design. The proposed robot manipulator controller is operated by adjusting its gains based on the response of the manipulator in such a way that the manipulator closely matches the reference model trajectories predefined by the designer. The manipulator control system studied has two loops: they are an inner loop on adaptive model following controller to compensate nonlinearity in the manipulator dynamic equation and to decouple the coupling terms and an outer loop of state feedback controller with integral action to guarantee the stability of the adaptive scheme. This adaptation algorithm is based on the hyperstability approach with an improved Lyapunov function. The coupling among joints and the nonlinearity in the dynamic equation are explicitly considered. The designed manipulator controller shows good tracking performance in various cases, load variation, parameter uncertainties. and time delay. Since the proposed adaptive control method requires only a small number of parameters to be estimated, the controller has a relatively simple structure compared to the other adaptive manipulator controllers. Therefore, the method used is expected to be well suited for a high performance robot controller under practical operation environments.

• 인터넷정보학회논문지
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• 제21권3호
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• pp.83-92
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• 2020

최근에 많은 기업 및 조직들이 비즈니스 프로세스 모델의 효율적 운용을 위해 예측적 프로세스 모니터링에 관심이 높아지고 있다. 기존의 프로세스 모니터링은 특정 프로세스 인스턴스의 경과된 실행상태에 초점을 두었다. 반면, 예측적 프로세스 모니터링은 특정 프로세스 인스턴스의 미래의 실행상태에 대한 예측에 초점을 둔다. 본 논문에서는 예측적 프로세스 모니터링 기능 중 하나인 비즈니스 프로세스 인스턴스 실행 잔여시간 예측기능을 구현한다. 잔여시간을 효과적으로 모델링하기 위해 액티비티별 속성에 따른 시간특징 값 분포 차이를 고려하여 액티비티별 특징 정규화를 제안하고 예측모델에 적용한다. 본 논문에서 제안된 모델의 예측성능 우수성을 입증하기 위해서 4TU.Centre for Research Data에서 제공하는 실제 기업의 이벤트 로그 데이터를 통해 선행연구들과 비교평가 한다.

• 한국환경과학회지
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• 제28권12호
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• pp.1133-1145
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• 2019

Successful launch requires state-of-the-art launch vehicle technology and constant test operations, However, the meteorological threat to the launch vehicle flight trajectory is also an important factor for launch success. Atmospheric stability above the Naro Space Center at the this time is very important, especially because the initial flight operation can determine the success of the launch. Moreover, during the flight of launch vehicle with rapid pressure and thrust into the atmosphere, convection activity in the atmosphere may create environmental conditions that cause severe weather threats such as thunderstorms. Hence, studies of atmospheric instability characteristics over the Naro Space Center are a necessary part of successful launch missions. Therefore, the main aims of this study were to (1) verify the atmospheric stability index and convection activity characteristics over the Naro Space Center using radiosonde data observed from 2007 to 2018 by the Naro Space Center, (2) analyze changes in the atmospheric stability index according to monthly and seasonal changes, and (3) assess how the calculated atmospheric stability index is related to actual thunderstorm occurrence using statistical analysis. Additionally, we aimed to investigate the atmospheric characteristics above the Naro Space Center through the distribution chart of the atmospheric stability index during summer, when convection activity is highest. Finally, we assessed the relationship between lightning occurrence and unstable atmospheric conditions, through predictability analysis performed using the lightning observation data of the Korea Meteorological Administration.

• Transactions on Electrical and Electronic Materials
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• 제18권4호
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• pp.199-202
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• 2017

Silicon carbide (SiC) is being spotlighted as a next-generation power semiconductor material owing to the characteristic limitations of the existing silicon materials. SiC has a wider band gap, higher breakdown voltage, higher thermal conductivity, and higher saturation electron mobility than those of Si. When using this material to implement Schottky barrier diode (SBD) devices, SBD-state operation loss and switching loss can be greatly reduced as compared to that of traditional Si. However, actual SiC SBDs exhibit a lower dielectric breakdown voltage than the theoretical breakdown voltage that causes the electric field concentration, a phenomenon that occurs on the edge of the contact surface as in conventional power semiconductor devices. Therefore in order to obtain a high breakdown voltage, it is necessary to distribute the electric field concentration using the edge termination structure. In this paper, we designed an edge termination structure using a field plate structure through oxide etch angle control, and optimized the structure to obtain a high breakdown voltage. We designed the edge termination structure for a 650 V breakdown voltage using Sentaurus Workbench provided by IDEC. We conducted field plate experiments. under the following conditions: $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $75^{\circ}$. The experimental results indicated that the oxide etch angle was $45^{\circ}$ when the breakdown voltage characteristics of the SiC SBD were optimized and a breakdown voltage of 681 V was obtained.

• 디지털콘텐츠학회 논문지
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• 제18권8호
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• pp.1577-1584
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• 2017

최근 전국적으로 많은 지자체들이 '도시재생특별법' 개정과 '도시재생 선도지역', '도시재생 뉴딜정책'의 추진으로 도시재생 사업을 추진하고 있지만, 공모사업 중심의 도시재생사업은 '도시재생특별법'에 의한 도시재생 계획체계에 맞게 추진하기에는 한계가 있다. 이처럼 공모사업 중심의 획일적인 계획과 비 계획체계에 의한 도시재생사업 추진되고 있어 많은 전략계획과 활성화계획 등 계획수립 소요시간 증가와 이에 따른 사회적 비용증가 등 많은 문제점을 야기하였다. 이에 본 연구에서는 도시재생 계획체계 정립 및 유연화 등의 방법론을 모색하고자 함을 목적으로 도시재생 계획체계의 운영 실태를 분석하여 문제점을 분석하고 개선 방안을 제시하여 우리나라의 도시재생 계획체계 재정립 등의 방안을 연구하고자 한다.