• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.55-59
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• 2002

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current -fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• 한국구조물진단유지관리공학회 논문집
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• 제17권5호
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• pp.1-12
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• 2013

본 연구는 보강재를 사용하지 않은 기존 RC기둥과 CSF (고연성재로 보강한 RC기둥) 등 2가지 형태의 기둥에 대한 내진성능특성과 변위연성도 특성 분석을 연구목적으로 한다. 이러한 특성들을 유한요소법에 의한 해석과 실험으로 분석한 결과, CSF의 균열양상과 하중-변위 곡선에 대한 실험치와 해석치는 유사함을 보였다. 보강하지 않은 기둥 (CNF)은 전단균열이 지배적이나 보강기둥 (CSF)은 휨균열이 지배적이다. 보강기둥의 최대변위 크기와 변위연성도는 CNF와 비교하여 큰 증가를 나타낸다. 그러므로 기존기둥의 내진성능과 변위연성도 향상시킬 때 CSF는 CNF의 대체구조로 사용할 수 있다.

• 전기학회논문지P
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• 제52권2호
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• pp.49-55
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• 2003

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• 한국자동차공학회논문집
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• 제12권1호
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• pp.106-113
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• 2004

Most of mechanical structures are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. In this study, the dynamic response of vehicle structure to external forces is classified an inverse problem involving strains from the experiment and the analysis. The practical dynamic forces are determined by the combination of the analytical and experimental method with analyzed strain by quasi-static finite element analysis under unit force and with measured strain by a strain gage under driving load, respectively. In a stressed body, inter-molecular chemical bonds are failed beyond the certain magnitude. The failure of molecular structure in material is considered as a time process of which rate is determined by mechanical stress. That is, the failure of inter-molecular chemical bonds is the fatigue lift of material. This kinetic concept is expressed as lethargy coefficient. And S-N curve is obtained with the lethargy coefficient from quasi-static tensile test. Equivalent practical dynamic force is obtained from the identification of practical dynamic force for one loading point. Using the practical dynamic force and S-N curve, fatigue life of a window pillar is analyzed with FEM under the identified force by the procedure of above mentioned.

• 한국정보통신학회논문지
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• 제19권11호
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• pp.2540-2545
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• 2015

본 논문에서는 복부 초음파 영상에서 충수를 추출하는 방법을 제안한다. 제안된 충수 추출 방법은 복부 초음파 영상에서 명암 대비를 강조하기 위해 Ends_in Search Stretching 기법을 적용하고, Max-Min 이진화, 영역 레이블링, 잡음제거, Cubic Spline 보간법을 적용하여 복부 근육의 하단 근막 부분을 추출한다. 그리고 초음파 영상에서 추출된 근막 영역을 제거한 후, ART2 알고리즘을 적용하여 충수를 추출한다. 제안된 방법을 초음파 영상에 적용한 결과, 제안된 충수 추출 방법이 효율적으로 충수가 추출되는 것을 영상의학과 전문의를 통하여 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.950-953
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• 2005

Floor impact sounds from two different floor systems were measured. One of the two floor systems is a dry floor system (with 150mm concrete slab) and the other is a standard floor system (210mm concrete slab). Real impact sources such as jumping and running of children were used as well as standard impact sources (bang machine, impact ball and tapping machine) to evaluate sound Isolation of the two floor systems. Subjective evaluations of the floor impact sound isolation performance for the two systems were also conducted by the methods of 3 scales & 9 categories, paired comparison and semantic differentials. Measurement results indicate that floor impact sound isolation performance of the dry floor was better than that of standard floor in both cases of real and standard impact sources. The subjects in auditory experiments also evaluated the dry floor as a better sound isolation system.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.335-342
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• 1997

Experiments were conducted to evaluate the hazard risks of vehicle fires. Sensors were strategically placed in passenger cars to determine the temperature, propagation rate and direction of flame. The life safety hazard evaluations such as smoke and gas analysis were included. An important ignition position was performed in the engine compartment. The effects of different ignition positions and the opening of door glasses were also reviewed. The experimental results indicate that the maximum temperature when a vehicle burns varies commonly from 90$0^{\circ}C$ -100$0^{\circ}C$. The flame reaches in the face of a driver about 6-7minutes and the windshield glass breaks about 10 minutes after the ignition in the engine compartment of vehicle. And the smoke and gas concentrations reached the limit of human inhalation after 13-14 minutes. Especially the concentrations of carbon monoxide exceeded the TWA(50 ppm) during short time after ignition in cases of all experiments.

• 한국의류학회지
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• 제46권2호
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• pp.310-320
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• 2022

This study aimed to ascertain the most efficient level of compression to be applied on a particular area along the upper extremities whilst developing functionality to prevent musculoskeletal disorders among workers who frequently use their arms. The compression areas were divided into upper arm, forearm, and wrist. The compression levels were applied using three types of bands. Comparisons on these bands' usability were based on evaluations of recorded brainwaves and subjective sensation response. Nine men in their twenties were selected for the experiment. The results revealed that when compression was applied, the left and right occipital lobes, plus the parietal lobe, were activated. Also, the alpha wave activity tended to increase, thereby exemplifying the compression's positive effects. The most physiologically efficient and subjectively preferred compression levels were 1.3 and 2.6 kPa for the upper arm and wrist. Furthermore, the compression level at the forearm should be at least 2.0 kPa.

• 디지털산업정보학회논문지
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• 제19권1호
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• pp.91-107
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• 2023

With the recent expansion of the commerce ecosystem, a large number of user evaluations have been produced. Accordingly, attempts to create business insights using user evaluation data have been actively made. However, since user evaluation can change after the user experiences the product, it is difficult to say that the analysis based only on reviews immediately after purchase fully reflects the user's evaluation of the product. Moreover, studies conducted so far on user evaluation have overlooked the fact that the length of time a user has used a product can affect the user's product evaluation. Therefore, in this study, we build a model that predicts the direction of change in the user's rating after use from the user's rating and reviews immediately after purchase. In particular, the proposed model reflects the product's period of use in predicting the change direction of the star rating. However, since the posterior information on the duration of product use cannot be used as input in the inference process, we propose a structure that utilizes information about the product's period of use using an auxiliary classifier. As a result of an experiment using 599,889 user evaluation data collected from the shopping platform 'N' company, we confirmed that the proposed model performed better than the existing model in terms of accuracy.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.536-545
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• 2024

Radioactive iodine is a representative fission product to be quantified for the safety assessment of nuclear facilities. In integral severe accident analysis codes, the iodine behavior is usually described by a multi-physical model of iodine chemistry in aqueous phase under radiation field and mass transfer through gas-liquid interface. The focus of studies on iodine source term evaluations using the combination approach is usually put on the chemical aspect, but each contribution to the iodine amount released to the environment has not been decomposed so far. In this study, we attempted the decomposition by revising the two-film theory of molecular-iodine mass transfer. The model involves an effective overall mass transfer coefficient to consider the iodine chemistry. The decomposition was performed by regarding the coefficient as a product of two functions of pH and the overall mass transfer coefficient for molecular iodine. The procedure was applied to the EPICUR experiment and suppression chamber in BWR.