• 한국콘텐츠학회논문지
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• 제15권2호
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• pp.393-407
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• 2015

본 연구는 소상공인 창업환경이 실패부담감과 창업실패에 미치는 영향을 알아보는데 목적을 갖고, 서울지역소재 소상공인 경영자 300명을 대상으로 설문조사하였다. 분석결과 첫째, 창업환경이 실패부담감에 미치는 영향은 경영자 환경, 비즈니스적 환경, 조직내부 환경, 조직외부 환경이 실패부담감에 부(-)의 영향을 미쳤다. 둘째, 창업환경이 재무적 비재무적 손실에 미치는 영향은 창업경영자 환경, 창업비즈니스적 환경, 조직내부 환경이 재무적 비재무적 손실에 부(-)의 영향을 미쳤다. 셋째, 실패부담감이 창업실패에 미치는 영향은 실패부담감이 재무적 비재무적 손실에 정(+)의 영향을 미치는 것으로 나타나 경영자 자질, 기업가정신, 비즈니스적 환경의 비해 조직내부 결속, 소통력 요인이 실패부담감과 재무적 비재무적 손실에 영향을 미치는 중요 속성임을 입증해 주었다.

• 조명전기설비학회논문지
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• 제15권1호
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• pp.51-58
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• 2001

현재의 DC-DC 컨버터는 스위칭 주파수를 높임에 따라 전체 손실이 현저히 증가하고 있다. 스위칭 손실을 줄이기 위해 사용한 예전의 soft 스위칭기술은 심지어 전압/전류 부담(stress)을 가중시켰다. 이에 대한 대책으로 soft 스위칭을 위한 공진회로를 주전력선에 병렬로 연결하고 보조 스위치를 이용하여 주 스위치의 turn-on 직전에만 공진회로를 동작시키는 유사공진 컨버터(QRC)기술이 발전되었다. 그러나 이 기술을 사용하는 컨버터에서도 손실은 여전히 발생하며 효율에 대한 전체적인 손실량은 알 수 있지만 각 소자에 대한 손실량은 알아볼 수 없었다. 따라서 본 논문에서는 컨버터의 주전력단에 사용되는 반도체 소자들의 선형화 된 손실등가 모델을 만들고 스위칭 시의 전압/전류 파형을 바탕으로 선형 특성을 고려하여 전체 손실에 대한 각 소자의 손실과 스위칭 손실을 분석하였다.

• 전기학회논문지P
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• 제59권4호
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• pp.358-363
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• 2010

This paper proposes a step-by-step method of determining the parameters of equivalent circuit which is considered the no load losses for the single phase induction motor which has the starting winding. This method is comprised of three steps, and the stator resistance which is measured by the method of voltage drop is treated as constant and the stator and the rotor leakage reactances are assumed to be the same in every step. The test results of no load and locked rotor test are used in the 1st and 2nd step, and the ratings of name plate of the motor are needed in the 3rd step. In the 1st step, the traditional equivalent circuit parameters are directly calculated by no load and locked rotor conditions. In the next step, five nonlinear simultaneous equations for five unknown parameters can be set up by no load and locked rotor equivalent circuits. These equations are solved by using the initial parameters obtained by the 1st step parameters. In the final step, three nonlinear simultaneous equations for rotor winding resistance, leakage reactance and no load losses component resistance can be set up by equivalent circuit under the rated operation. Three parameters are solved by using the 2nd step parameters. Thus, equivalent circuit parameters are gradually refined step by step. The validity of the proposed method is evaluated by comparing the computed values obtained by the equivalent circuit parameters with the experimental values of the load test.

• 정보보호학회논문지
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• 제12권3호
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• pp.39-47
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• 2002

본 논문은 다수의 호스트가 임의의 IP 주소로 목적지 호스트를 공격하는 분산 서비스거부 공격의 경우에 패킷의 전송경로를 역추적하기 위한 새로운 접근 방법에 대해 연구한다. 목적지 호스트는 전송되는 트래픽에 대하여 패킷들의 전송상태 및 전체 손실률을 계산한 후, 이를 바탕으로 소스 호스트들까지 논리적인 전송 경로를 역추적 하게 된다. 이는 동일경로를 따라 전송되는 패킷들의 손실에는 상호 연관성이 있다는 점에 근거하였으며, 시뮬레이션 결과는 특정 조건 하에서 매우 우수한 성공률을 보인다. 제안된 방식은 실시간 혹은 비 실시간으로 처리할 수 있으며. 기존의 방법들과 달리 라우터의 특정 기능이나 ISP의 도움 없이 목적지 호스트를 독자적으로 추론할 수 있다는 장점이 있다. 이 결과는 물리적인 전송경로의 추정 및 기존의 역추적 방법에 대한 보완에 적용될 수 있다.

• 한국콘텐츠학회논문지
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• 제21권11호
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• pp.692-710
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• 2021

본 연구에서는 Brothers 등(2019)에 의해 개발된 노화인식 척도(Awareness of Age-Related Change Scale, AARC)의 한국판 타당화 작업을 수행하였다. 노인 당사자의 노화인식을 확인하기 위해 만 65세 이상의 노인 400명을 대상으로 연구를 수행하였다. 두 개의 표본(표본 1: 185명, 표본 2: 215명)을 대상으로 한국어로 번안한 노화인식 척도에 대해 탐색적 요인분석 및 확인적 요인분석을 시행하였다. 탐색적 요인분석에서는 손실 인식 요인은 건강 영역 손실 인식, 건강 외 영역 손실 인식의 두 가지 하위요인으로 구성되고, 이득 인식은 하위요인 없이 단일 요인으로 구성되는 것으로 나타났다. 확인적 요인분석 결과, 탐색적 요인분석 결과로 도출된 요인 구조가 경쟁모형보다 더 타당하였다. 또한 구성타당도를 검증하기 위해 노화태도와 상관분석, 정서경험에 대해 회귀분석을 수행하였다. 마지막으로 본 연구의 의의 및 활용방안을 논의하고, 한계 및 미래 연구를 위한 제언을 밝혔다.

• 한국농공학회논문집
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• 제64권3호
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• pp.53-61
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• 2022

This study evaluated the impacts of subsurface drainage design, i.e., spacing and depth, on agricultural productivity and environmental sustainability in two tile-drained fields (Sites A and E) under a corn-soybean rotation in the Midwestern United States. A calibrated and validated Root Zone Water Quality Model (RZWQM) was used to simulate Nitrate-N (nitrogen) losses to tile drainage and crop yields of 30 tile spacing and depth scenarios over 24 years (1992-2015). Our results presented that the narrower and deeper the tile drains are placed, the greater corn yield and Nitrate-N losses, indicating that the subsurface drainage design may cause a trade-off between agricultural productivity and environmental sustainability. The simulation results also presented that up to about 255.7% and 628.0% increase in Nitrate-N losses in Sites A and E, respectively, far outweigh the rate of increase in corn yield up to about 1.1% and 1.6% from the adjustment of tile spacing and depth. Meanwhile, the crop yield and Nitrate-N losses according to the tile configuration differed depending on the field, and the soybean yield presented inconsistent simulation results, unlike the corn yield, which together demonstrate the heterogeneous characteristic of agro-environmental systems to a subsurface drainage practice. This study demonstrates the applicability of agricultural systems models in exploring agro-environmental responses to subsurface drainage practices, which can help guide the introduction and installation of tile systems into farmlands, e.g., orchards and paddy fields, in our country.

• 가족자원경영과 정책
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• 제8권1호
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• pp.1-13
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• 2004

This study examined in detail the Japanese system of redressing consumers' losses and the overall consumer administrative system and compared them with the Korean counterpart to seek for a direction of reforming the systems. Several policy suggestions could be made as follows to activate the systems and improve the performances of the consumer administration in both Japan and Korea. First, in Japan, consumer center must be efficiently operated while private consumer groups, firms, consumer agencies and other organizations must actively join to actively redress consumers' losses and implement other consumer policies. Second, in Korea, regional consumer policies are weak so that they must learn Japanese well-developed regional consumer administration system by examining their current development, strengths, and weaknesses. Third, working conditions must be urgently improved, increasing the number of consumer counselors who are involved in consumer policies as well as to guarantee minimum level of their payment. On the other hand, the trend of hiring married and old employees being responsible for implementing consumer policies in Japan must be improved. Fourth, divisions of works in consumer policies among consumer groups as well as their specialization in Korea are necessary. Finally, as counseling of consumers through internet were not available in Japan, that type of counseling must introduce and become more popular in the future.

• 전력전자학회논문지
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• 제18권3호
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• pp.247-255
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• 2013

In this paper, a soft switching DC-DC converter for AC module type photovoltaic (PV) module integrated converter is proposed. A push-pull converter is suitable for a low voltage PV AC module system because the step-up ratio of a high frequency transformer is high and the number of primary side switches is relatively small. However, the conventional push-pull converters do not have high efficiency because of high switching losses by hard switching and transformer losses (copper and iron losses) by high turns-ratio of the transformer. In the proposed converter, primary side switches are turned on at zero voltage switching (ZCS) condition and turned off at zero current switching (ZVS) condition through parallel resonance between secondary leakage inductance of the transformer and a resonant capacitor. Therefore the proposed push-pull converter decreases the switching loss using soft switching of the primary switches. Also, the turns-ratio of the transformer can be reduced by half using a voltage-doubler of secondary side. The theoretical analysis of the proposed converter is verified by simulation and experimental results.

• Steel and Composite Structures
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• 제19권1호
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• pp.43-58
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• 2015

There are many studies on the optimization of steel trusses in literature; and, a large number of them include a shape optimization. However, only a few of these studies are focused on the prestressed steel trusses. Therefore, this paper aims to determine the amounts of the material and cost savings in steel plane trusses in the case of prestressing. A parallel-chord simply supported steel truss is handled as an example to evaluate the used approach. It is considered that prestressing tendon is settled under the bottom bar, between two end supports, using deviators. Cross-sections of the truss members and height of the truss are taken as the design variables. The prestress losses are calculated in two steps as instantaneous losses and time-dependent losses. Tension increment in prestressing tendon due to the external loads is also considered. A computer program based on genetic algorithm is developed to solve the optimization problem. The handled truss is optimized for different span lengths and different tendon eccentricities using the coded program. The effects of span length and eccentricity of tendon on prestressed truss optimization are investigated. The results of different solutions are compared with each other and those of the non-prestressed solution. It is concluded that the amounts of the material and the cost of a steel plane truss can be reduced up to 19.9% and 14.6%, respectively, by applying prestressing.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.225-229
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• 2017

This paper describes the loss analysis based on load conditions of the air conditioning compressor motors using variable dc-link voltage. The losses of PMSM (Permanent Magnet Synchronous Motor) should be analyzed by the PWM (Pulse Width Modulation) output of inverter. The harmonic loss by the PWM cannot consider that using the current source analysis of the inverter. In addition, when the voltage of dc-link is variable with the condition of variable speed and load conditions in motor, the losses of motor are also changeable, however it is hard to analyze those losses by only electromagnetic finite element method (FEM). Therefore, this paper proposes the analysis method considering the carrier frequency of the inverter and the varying state of the dc-link voltage through the FEM-control coupled analysis. Using proposed analysis method, additional core loss and eddy current loss of permanent magnet caused by PWM could be analyzed. Finally, the validity of the proposed analysis method is verified through the comparison the result of coupled analysis with experiment.