• Transactions on Electrical and Electronic Materials
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• 제9권6호
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• pp.260-264
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• 2008

The operational characteristics of superconducting amplifier using vortex flux flow were analyzed from an equivalent circuit in which its current-voltage characteristics for the vortex motion in YBCO microbridge were reflected. For the analysis of operation as an amplifier, dc bias operational point for the superconducting amplifier is determined and then ac operational characteristics for the designed superconducting amplifier were investigated. The variation of transresistance, which describes the operational characteristics of superconducting amplifier, was estimated with respect to conditions of dc bias. The current and the voltage gains, which can be derived from the circuit for small signal analysis, were calculated at each operational point and compared with the results obtained from the numerical analysis for the small signal circuit. From our paper, the characteristics of amplification for superconducting flux flow transistor (SFFT) could be confirmed. The development of the superconducting amplifier applicable to various devices is expected.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.271-277
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• 2003

It is important to control layer current distributions of coaxial multi-layer HTS cables, because a homogeneous layer current distribution decreases AC loss and can supply the largest operational current. We have extended the theory that treat the operational current more than the critical current by considering V-I nonlinear characteristics of HTS tapes including flux flow resistance and contacting resistance between the cable and terminals. It is important to investigate the current distribution under the condition of operational current more than the critical current of cable, because the cable has experiences of fault current. In order to verify the extended theory, we have fabricated a two layers cable with the same twisting layer pitch. It was observed that almost all the operational current less than the critical current flowed on the outer layer because of its lower inductance. In case of operational current more than critical currents of layers, the flux flow resistances affect strongly current waveform and thereby the currents of layers were determined by the flux flow resistances. And we investigated breakdown characteristics in $LN_{2}$/paper composite insulation system for the application to a HTS cable. In this experiment, we got some information out of that the electrical characteristics of the insulation materials depends on the condition of butt gap.

• 센서학회지
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• 제1권1호
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• pp.13-21
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• 1992

Hall 소자 및 OP-앰프의 장점을 동시에 살린 'Hall 소자를 이용한 자기연산증폭기'를 구성하였다. 이 자기연산증폭기는 높은 입력임피던스 회로와 두 신호의 차 신호를 하나의 신호로 변환하는 회로를 반드시 필요로 하고, 또 이것을 연산처리하기 위해 궤환 입력을 받아 들일 수 있어야 한다. 본 논문에서는 이러한 특성을 만족하는 새로운 '두 신호의 차 신호를 하나의 신호로 변환하는 연산증폭기(DSCOP)'를 제안하였다. 그리고 제안된 DSCOP와 Hall 소자를 이용하여 자기연산증폭기를 설계하여 그 특성을 시뮬레이션 하였으며, 실지로 시스템을 개별소자로 구성하여 측정하였다.

• 제어로봇시스템학회논문지
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• 제7권1호
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• pp.1171-1177
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• 2001

This paper provides a guideline for specifying the operational compliance characteristics considering the location of compliance center and the grasp points in assembly tasks using robot hands. Through various assembly tasks, we analyze the conditions of the achievable operational stiffness matrix with respect to the location of compliance center and the grasp points. Also, we show that some of coupling stiffness elements in the operational space cannot be planned arbitrarily. As a result it is concluded that the location of compliance center on the grasped object and the grasp points play important roles for successful assembly tasks and also the operational stiffness matrix should be carefully specified by considering those conditions.

• Structural Engineering and Mechanics
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• 제74권1호
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• pp.121-128
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• 2020

This paper presents an experimental study on the dynamic characteristics of infilled reinforced concrete (RC) frames. A 1/3-scaled, one-bay, three-storey RC frame was produced and tested by using operational modal analysis (OMA). The experiments were performed on five specimens: one reference frame with no infill walls and four frames with infill walls. The RC frame systems included infill walls made of hollow clay brick, which were constructed in four different patterns. The dynamic characteristics of the patterns, including the frequency, mode shapes and damping ratios in the in-plane direction, were obtained by 6 accelerometers. Twenty-minute records under ambient vibration were collected for each model, and the dynamic characteristics were determined using the ambient vibration testing and modal identification software (ARTeMIS). The experimental studies showed that the infill walls significantly affected the frequency value, rigidity and damping ratio of the RC frame system.

• 한국식품조리과학회지
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• 제11권3호
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• pp.295-302
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• 1995

The purposes of the study were to identify the operational characteristics in employee feeding facilities, and to examine the correlations of productivity and these characteristics. A questionnaire was developed and mailed the 500 dietitians in employee feeding facilities in Seoul and Kyoungki Do. Usable questionnaires were received from 117 respondents for a response rate of 23.4％. The questionnaire was designed to determine the productivity index and to investigate the relationship between operational characteristics and productivity index. The questionnaire was contained 2 parts with a total of 16 statements. Data were analyzed for descriptive statistics and Pearson correlation analysis using SPSS/PC programs. The average productivity indices of 117 facilities were 6.91 meals/hr. Total meals served/week was significantly correlated to the productivity index (r=0.441, p < 0.001). No of average servings per meal, percentage of convenience food use, average minutes for service/day, and employment in professional practice of dietitian were also positively correlated, while food cost was negatively correlated to the productivity.

• Computers and Concrete
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• 제12권1호
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• pp.79-90
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• 2013

In this study, dynamic characteristics such as natural frequencies, mode shapes and damping ratios of RC frame is determined for different construction stages using Operational Modal Analyses method under ambient vibration. Full scaled, one bay and one story RC frames are selected as an application for different construction stages such as plane, brick in-filled and brick in-filled with plaster. The RC frame is vibrated by natural excitations with small impact effects and the response signals are measured using sensitive accelerometers during ambient vibration tests. Measurement time-frequency span and effective mode number are determined by considering similar studies in literature. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, output-only system identification technique is employed namely; Enhanced Frequency Domain Decomposition technique in the frequency domain. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of RC frames.

• 안보군사학연구
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• 통권3호
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• pp.73-120
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• 2005

Today's world is generation of Transformation. The Term "Transformation" is widely used in many nations and international organizations such as U.S. and NATO to describe the course of change undertaken by militaries to respond to the new and emerging security environment. Transformation involves all elements of the defense enterprise including Operational Environment, Operational Concepts, Doctrine, Structure and Technologies, within a supportive Cultures context. An Operational Environment is defined as "a composite of conditions, circumstances, and influences that affect the employment of military forces and bear on the decisions of the unit commander." The context for developing future military concept and capability lies essentially within the anticipated boundaries of the operational environment in a collective sense. The joint operational environment is essential to the nation's defense. It describes volatile, complex, and dangerous environment in which the military personnel. organizations, and material will operate. Implications coming forth from joint Operational Environment are but a starting point - many others exist. More and better Implications will come forth as people think about massages of Operational Environment, experiment its characteristics, learn to deal with its threats and scenarios, apply their experience and judgement, and then consider what is required of Korean military doctrine, organizations, training and education, material development, and leadership for operations in the joint Operational Environment.

• 한국항만경제학회지
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• 제27권3호
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• pp.13-39
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• 2011

공급사슬관리에 관한 많은 선행연구들이 지속적으로 공급사슬성과의 향상을 위해서는 협업이 필요하다고 주장하고 있다. 본 연구는 물류기업의 관계특성, 협업, 성과 간의 인과관계를 밝히는 것이며, 특히 관계특성과 성과 간의 관계에서 매개변수로서 두 종류의 협업(운영적 협업과 전략적 협업)에 초점을 맞추고 있다. 분석을 위해 물류기업 164개의 자료가 사용되었으며, PLS를 이용해 구조모형을 분석하였다. 분석결과 신뢰성, 정보공유는 운영적협업에 긍정적인 영향을 미쳤으며, 운영적 협업은 공급사슬 성과에 긍정적인 영향을 미치는 것으로 나타났다. 거래지속의지와 정보공유는 전략적 협업에 긍정적인 영향을 미쳤으나, 전략적 협업은 공급사슬 성과에 긍정적인 영향을 미치지 않는 것으로 나타났다. 따라서 관계 특성과 공급사슬성과 사이에는 운영적 협업이 매개역할을 하는 것으로 나타났다.

• 한국소음진동공학회논문집
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• 제27권1호
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• pp.107-113
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• 2017

The dynamic characteristics including natural frequencies and excitation frequencies are evaluated for a small 10 kW vertical axis wind turbine. Acceleration responses were measured at 12 distributed locations for impact vibration tests, ambient vibration tests during non-operational and operational conditions, and braking tests during operational condition. The natural frequencies for the lowest 2 bending modes and the first torsional mode were estimated and also the excitation frequencies, i.e. 1P, 2P, 4P, were also estimated according to the rotational speed using the responses under operational conditions (i.e. power generation condition).