• 동력기계공학회지
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• 제18권3호
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• pp.87-92
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• 2014

This study is aimed at investigating the thermal behavior of immersion-cooled high power LED lighting engines. 3D CFD models have been generated for the numerical analysis. Five cases in terms of the configuration of LED chips have been explored for various passive cooling conditions of the lighting engine, i.e., the natural air convection with a lens, the natural air convection without a lens, the deionized water-immersion cooling condition with a lens. The numerical study reveals that the deionized water-immersion cooled lighting engine has nearly twice better thermal performance than the natural air convection cooled lighting engine containing a lens. The investigation has also demonstrated that the four chips configuration has the better thermal performance than the single chip configuration.

• Nuclear Engineering and Technology
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• 제32권1호
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• pp.10-16
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• 2000

Preliminary experiment was peformed to investigate the leaching characteristics of paraffin waste forms that had been recently generated in large quantities at domestic nuclear power plants. At first, waste simulants whose compositions were different in mixing ratio of paraffin to boric acid were prepared. Their compressive strengths were measured and ninety-day leaching test of specimen including cobalt was carried out according to ANSI/ANS-16.1 test procedure. Water immersion test was also conducted keeping pace with leaching test and the weight change and the compressive strength of specimen were observed after ninety days. The compressive strength of waste form exhibited 666 psi (4.53 MPa) in the case where mixing ratio of boric acid to paraffin was 78/22, which was adopted in concentrate waste drying system of domestic nuclear power plants. The leaching test resulted in about 50% of the cumulative fraction leached for boric acid and cobalt, respectively. The specific gravity of waste form was 0.87 ［g/g］whose value was less than that of water because the weight loss of about 39% occurred after the water immersion test of ninety days. It was also observed that the waste form which had undergone ninety-day water immersion test exhibited the compressive strength of 203 psi (1.38 MPa).

• 한국멀티미디어학회논문지
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• 제20권4호
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• pp.686-695
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• 2017

The purpose of the study is to analyze the impact of storytelling factor, technical factor and exhibition environment factor on the degree of satisfaction, degree of immersion and immersion types in and . Our findings show that the degree of satisfaction not only has a significant correlation with the degree of immersion, but also influences on the holding power and behavioral intention. According to the results of correlation analyses, three factors have an impact on the degree of satisfaction and immersion. Immersion factors influence negatively on Focused Attention and Heightened Enjoyment, however, the factors effect positively on Temporal Dissociation and Curiosity. As the influence of immersiveness on the degree of satisfaction and immersion, and immersion types have been verified, this study offers a fresh understanding of the importance of immersion factors as evaluation criteria for digital exhibitions.

• 인지과학
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• 제15권3호
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• pp.45-55
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• 2004

몰입이란 이끌린 무엇인가에 전념한 상태를 의미한다. 컴퓨터 게임에 빠져 있을 때에도 이러한 몰입을 경험할 수 있다. 본 논문에서는 멀티미디어 게임의 흡인요소를 분석하였다. 몰입이론을 기초로 분석한 결과, 인지 및 감성을 고려한 흡인요소에는 22가지가 있었다. 이와 함께 몰입차원, 구현방식, 자극방법의 각도에서 흡인요소들의 상관관계를 분석하였다. 그 결과 새로운 게임을 설계할 때 우선적으로 고려해야 할 흡인요소가 일체감, 자극성, 도박, 현장감, 환상감, 만족감, 성취감 등의 7가지로 밝혀졌다. 한편, 22가지 흡인요소를 기저범주로 두고 참조정보를 이용하여 Roget 시소러스 내에서 가까운 반경 안의 새로운 범주를 탐색하였다. 그 결과, 22가지 게임의 흡인요소를 229가지로 세분화시킬 수 있었다. 이러한 본 논문의 결과를 활용한다면, 몰입력이 한층 강화된 멀티미디어 게임의 제작이 가능할 것이다.

• 동력기계공학회지
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• 제18권2호
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• pp.43-49
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• 2014

This study has been investigated on the durability of carbon fiber/epoxy composites (CFRP) in moisture environment. The carbon fiber/epoxy composites were modified to use the nanoparticles such as carbon nanotubes and titanium oxide. These hybrid composites were exposed to moisture environment for a certain period of time. Weight gain according to immersion time, quasi-static tensile test and micro-graphic characterization were investigated on the samples exposed to moisture environment. Consequently, the weight gains increased with increasing immersion time and weight gain of the hybrid composites was lower than the one of CFRP through the whole immersion time. The tensile strengths decreased with increasing immersion time and tensile strengths of the hybrid composites were higher than the one of CFRP through the whole immersion time. The CFRP were observed more degraded than hybrid compositess in moisture environment. Therefore, it was concluded that the addition of nanoparticles in CFRP could lead to improve the durability in moisture environment.

• 비파괴검사학회지
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• 제24권4호
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• pp.348-353
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• 2004

이 연구는 터빈베어링의 신뢰성을 평가하기 위하여 초음파 C-Scan 방법을 적용한 기술이다. 수침법에 관한 연구는 실험실과 현장검사 적용에 광범위하게 사용되는 기술이다. 여기에서는 C-Scan 방법을 이용하여 베어링의 모재와 Babbitt 금속간 경계부의 상태를 평가하였다. 수침법 C-Scan 방법에 의한 초음파 영상은 베어링 경계부의 상태를 확인하는데 효과적인 방법으로 사용될 수 있었다. 초음파 영상의 분해능을 높이기 위하여 집속형 탐촉자를 사용하고, Babbitt 금속과 베어링 모재간의 접합경계면에서 발생하는 초음파 음압 반사율을 측정하여 결함의 검출과 면적을 추정할 수 있었다. 초음파 수침법은 베어링 접합부의 박리위치와 박리면적의 경계면을 결정하여 크기를 계산하는데 아주 유용하게 사용될 수 있는 기술이며, 이 연구에서 개발된 기술은 화력발전소에서 사용되고 있는 터빈베어링의 건전성을 확보하는데 적용되었다.

• 센서학회지
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• 제24권6호
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• pp.392-397
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• 2015

Recently computer games have been widely spread. For the purpose of studying brain activities, EEG was measured during the computer game and analyzed in terms of channels and frequency bands. EEG data were obtained during the resting state and game immersion. Then the power spectra of alpha, beta and theta bands were computed. During game immersion, the ratio between theta / alpha could effectively differentiate between rest and game immersion. Changes in brain activity (26~53%) were observed in the parietal and occipital lobes. Interestingly, immersion shows different features compared to concentration. The state of game immersion could be detected. Therefore, it is possible to utilize the state of immersion as one of the game parameters or to generate a control signal that may be used to provide a warning message or abort the game when the situation of the excessive indulgence in the game reaches. EEG can be applied as smart interface for computer game.

• 한국식생활문화학회지
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• 제23권5호
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• pp.572-581
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• 2008

The principal objective of this study was to determine how the internal marketing of the contract foodservice management company affects job satisfaction and organization immersion, as well as the influence of the satisfaction of internal customers (employees) has on job satisfaction and organization immersion, and the function as a preceding variable that improves service quality. T-test, ANOVA, and linear regression analysis was conducted to analyze the hypotheses of the study. The summary of study as per the result of this corroborative study is presented as follows: It was verified that internal marketing affects organizational immersion and the job satisfaction of employees, and job satisfaction plays a crucial role in organizational immersion. Moreover, it was also confirmed that the higher the internal marketing is, the higher the job satisfaction and organization immersion will be, thereby improving the service quality provided by employees. If enterprise regards employees as internal customers and constantly and efficiently conducts internal marketing activities such as internal communication, training, welfare, compensation, delegation of power, supporting the management, etc, the organizational immersion and job satisfaction of employees will be heightened, thereby enhancing loyalty and pride in the organization to provide services with better quality.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권4호
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• pp.58-66
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• 2020

Since the typical horn-type ultrasonic equipment induces a reaction at the probe tip, the sonochemical reaction has a limitation that it occurs only in a specific area. As one of the ways to overcome this limitation, an ultrasonic device with multi-stepped horn equipped with several oscillators has been developed. The objective of this study was to investigate the sonochemical effects induced by acoustic cavitation system in 20 kHz multi-stepped ultrasonic horn using calorimetry, KI dosimetry and the luminol test. The sonochemical effects of multi-stepped ultrasonic horn were compared with that of the typical horn-type 20 kHz ultrasonic device. The effect of immersion depth and power on the sonochemical reaction was investigated in the ultrasonic system with multi-stepped ultrasonic horn. Higher calorimetric energy was obtained at higher immersion depth and power conditions. Sonochemical effects increased significantly when using the high immersion depth and input power. However, as the input power increased, the cavitation reaction zone concentrated around the ultrasonic horn. Additionally, the experiments to examine the effect of liquid temperature was conducted. The smaller sonochemical reaction was obtained for the higher liquid temperature. The effect on temperature seems to be closely related to liquid conditions such as viscosity and vapor pressure of water.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.1-8
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• 2017

Recently, Research and development activity of HTS (High Temperature Superconducting) power application is very progressive worldwide. Especially, HTS cable system and HTSFCL (HTS Fault current limiter) system are proceeding to practical stages. In such system and equipment, cryogenic cooling system, which makes HTS equipment cooled lower than critical temperature, is one of crucial components. In this article, cryogenic cooling system for HTS application, mainly cable, is reviewed. Cryogenic cooling system can be categorized into conduction cooling system and immersion cooling system. In practical HTS power application area, immersion cooling system with sub-cooled liquid nitrogen is preferred. The immersion cooling system is besides grouped into open cycle system and closed cycle system. Turbo-Brayton refrigerator is a key component for closed cycle system. Those two cooling systems are focused in this article. And, each design and component of the cooling system is explained.