• 해양환경안전학회지
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• 제12권1호
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• pp.53-59
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• 2006

해상에서 해양사고를 예방하고 선박의 통항안전성을 증대시키기 위해 연안 VTS와 항행보조시설이 적극 검토되고 있다. 그러나 이러한 시설의 설치에는 막대한 비용과 예산이 든다. 따라서 연안해역에 통항 위험성을 평가하여 우선순위를 결정해야하고 통항 위험성평가는 조선자의 관점에서 평가되어야 한다. 한편, 인간의 사고에는 많은 형태의 애매함이 존재하기 때문에 이러한 애매함을 반영하기 위해 본 연구에서는 퍼지로직과 쇼케적분을 이용하여 연안해역의 선박 통항안전성을 평가하였다. 본 연구의 목적은 퍼지로직과 쇼케적분을 이용하여 조선부담감을 고려할 수 있는 평가모델을 개발하고 우리나라 연안해역을 8개로 나누고 연안 VTS와 항행보조시설 설치의 우선순위를 결정하기 위한 평가를 실시하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.502-504
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• 2008

A new output inductor less phase shift full bridge converter with current reduction technique for server power application is proposed in this paper. The proposed converter can reduce the current stress by using the auxiliary circuit. Since the auxiliary circuit causes the additional resonance between the leakage inductor and auxiliary capacitor before the powering period, the proposed converter has lower current stress even no output filter inductor. Small size and circulating energy can be also the merits of the proposed converter. The operational principles and analysis are presented. Experimental results demonstrate that the current stress can be reduced effectively by using the auxiliary circuit without large output filter inductor.

• 산업경영시스템학회지
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• 제21권47호
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• pp.57-68
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• 1998

Work environments have been changed with the advent of new technologies, such as computer technology. However, human cognitive limits can't pace up with the change of work environment. Designing human-computer system requires knowledge and evaluation of the human cognitive processes which control information flow workload. Futhermore, under limited reaction time and/or urgent situation, human operator may the work stress, work error and resultant deleterious work environment. This paper evaluate the visual factors of major information processing factors(information density, amount of information, operational speed of speed)on operator performance of supervisory control under urgent(limited reaction time)environments which require deleterious work condition. To describe the work performance int the urgent work situations with time stress and dynamic event occurrence, a new concept of information density was introduced. For a series of experiments performed for this study, three independent variables(information amount, system proceeding speed, information density) were evaluated using five dependent variables. The result of statistical analyses indicate that the amount of information affected on all of five dependent measure. Number of failure and number of secondary task score were influenced by both amount of information and operational speed of system. However reaction time of secondary task were affected by both amount of information and information density. As a result, the deleterious factors for the performances seemed to be a scanning time to supervise each control panel. Consequently, a new display panel was suggest to reduce operator work load for scanning task showing better operator performance.

• 드라이브 ㆍ 컨트롤
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• 제21권1호
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• pp.22-30
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• 2024

Gearboxes designed for reciprocating motion operating mechanisms operate under conditions where both the load and speed undergo continuous variations. When conducting durability tests on gearboxes designed for such applications, operating the target gearbox under conditions similar to the intended usage is essential. The gearbox must be operated for the required number of cycles to validate its durability under conditions mirroring its intended usage. This study devised an accelerated test method for gearboxes, which reduces operating angles and operational strokes. The reliability of the accelerated test was verified by comparing the stresses imposed on the gears under general and acceleration conditions through multi-body dynamic simulations. The results confirmed that the maximum contact stress levels under normal and accelerated conditions were within a 0.1% error range, indicating a minimal difference in the gear damage rates. However, a difference in the maximum contact stress results between the normal and accelerated conditions was observed when inertial forces acted on the output shaft due to the operational acceleration of the gearbox. Therefore, when conducting this acceleration test, caution should be exercised to ensure that the operational load on the gearbox, which affects inertia, does not significantly deviate from the conditions observed under normal operating conditions.

• 한국기계가공학회지
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• 제19권2호
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• pp.47-54
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• 2020

Themo-mechanical analysis was carried out using the finite element method for the steel shell of a cupola furnace. When the outer surface of the shell was cooled with water to within the temperature range of 35-80 ℃ during operation of the cupola, the inner surface of the shell was expected to exhibit a temperature of 65-248 ℃ based on heat transfer analysis. The shell was also expected to have an equivalent stress range of 100-280 MPa in the outer surface over the temperature range examined. Upon cooling the shell to obtain an outer surface temperature <80 ℃, the maximum equivalent stress of the shell did not exceed the yield strength. Although the temperature of the outer surface varied between 35 and 80 ℃ periodically due to the cooling control problem, the fatigue stress at the outer surface of the shell was calculated to be within the fatigue strength. During a non-operational period to examine the system between furnace operations, the thermal stress presented in the shell was sufficiently low to reach the desired yield strength and fatigue limit.

• 한국기록관리학회지
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• 제8권1호
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• pp.235-255
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• 2008

정부기관에 근무하는 기록연구사들의 근무실태와 직무만족, 제도운영의 개선방안을 파악하기 위해 설문조사와 면접조사를 실시하였다. 직무특성은 Hackman과 Oldham의 직무특성요인을 포함하여 전문성, 역할갈등, 스트레스, 이직의사의 9가지 항목으로 조사하였다. 직무환경은 의사소통, 참여, 인간관계, 상급자, 교육훈련의 5개 항목으로 구분하여 조사하였다. 직무만족은 일반적 만족도, 보람, 소명감의 3가지 항목으로 측정하였는데 모든 항목에서 매우 긍정적인 인식을 보여주었다. 제도운영의 개선을 위한 과제로는 조직편제, 업무분장, 인사관리, 중앙기록물관리기관과 기록관의 협력을 중심으로 의견을 분석하였다. 이상의 분석을 통해 시사점과 개선책을 제시하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.294-298
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• 2003

In this paper, the new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in, the main switch and the main diode. The Auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition, The resonant current required to obtain the ZCT is small and regenerated to the input voltage source. The operational principles of the boost converter integrated with the proposed ZCT circuit cell is analyzed theoretically and verified by the simulation and experimental result. Index terms - zero-current-transition (ZCT), zero-current- switching (ZCS), zero-voltage-switching (ZVS)

• Journal of Power Electronics
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• 제7권4호
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• pp.301-309
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• 2007

The flyback converter is one of the most attractive isolated converters in small power applications because of its simple structure. However, it suffers from high device stress, large transformer size, and high voltage stress across its switch and diode. To solve these problems a new cost-effective PWM single-switch isolated converter is proposed. The proposed converter has no output filter inductor, reduced voltage stress on the secondary devices, and reduced transformer size. Moreover, the switch turn-off loss is reduced and no dissipative snubber across the secondary diode is required. Therefore, it features a simple structure, a low cost, and high efficiency. The operational principle and characteristics of the proposed converter are presented and compared with the flyback converter and then verified experimentally.

• 전기학회논문지
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• 제56권7호
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• pp.1250-1254
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• 2007

The multi-resonant(MR) converter has a characteristics that the parasitic components existing in the converter are absorbed into the resonant circuits. The designed MR converter could be got a high efficiency and a high power density because the switching power losses are reduced effectively due to resonant switching circuit. However, the high resonant voltage stress of switching power devices leads to the conduction loss. In this paper, it is proposed the novel alternated(AT) flyback multi-resonant converter to overcome such a drawback. The suggested converter dc input is divided by two series input filter capacitors. The resonant stress voltage is reduced to 2-3 times the input voltage without any complexity and it provides the various circuit schemes in lots of applications. The proposed flyback MR converter is verified through simulation and experiment.

• Journal of Power Electronics
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• 제18권2호
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• pp.356-363
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• 2018

The combination of a buck converter and a forward converter can be considered to accomplish a high step-down non-isolated converter. To decrease the insufficient step-down ratio of a regular buck converter and to distribute switch voltage stress, a forward-integrated buck (FIB) converter is proposed in this paper. The proposed interleaved DC-DC converter provides an additional step-down gain with the help of a forward converter. In addition to its simple structure, the transformer flux reset problem is solved and an additional magnetic core reset winding is not required. The operational principle and an analysis of the proposed FIB converter are presented and verified by experimental results obtained with a 240 W, 150 V/24 V prototype.