• Journal of Power System Engineering
• /
• v.18 no.3
• /
• pp.87-92
• /
• 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
• /
• v.32 no.1
• /
• pp.10-16
• /
• 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).

• Journal of Korea Multimedia Society
• /
• v.20 no.4
• /
• pp.686-695
• /
• 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.

• Korean Journal of Cognitive Science
• /
• v.15 no.3
• /
• pp.45-55
• /
• 2004

Immersion means the state of total devotion to what one is involved in. The typical form of this immersion experience happens when one is engaging in computer games. We analyze how the users became immersed in computer games. There are 22 elements of immersion involved in cognitive and emotional fun based cm the flow theory. After analyzing these elements with respect to flow dimension and game mechanics, we find that there are differences in the degree of their immersion in games. There are 7 elements that may be considered preferentially in designing computer games: unity, stimulation, gambling, virtual reality, fantasy, satisfaction accomplishment. We match these elements to Roget's categories and search for new categories with heading information and reference information. As a result 22 immersion elements are subdivided into 229 factors in the concrete. With these factors, we can design a multimedia game which has mon powerful immersion.

• Journal of Power System Engineering
• /
• v.18 no.2
• /
• pp.43-49
• /
• 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.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.24 no.4
• /
• pp.348-353
• /
• 2004

This study is aimed for the implementation of ultrasonic method to assess the reliability of turbine bearings. A modified ultrasonic immersion technique was carried out in both laboratory experiment and field application. From the laboratory results, we confirmed that the condition of interface layer between the babbitt and base metal be monitored by the C-Scan. The C-scan image by the ultrasonic immersion test can be used successfully to observe the condition of interface layer. The testing with a focused transducer provides a promising approach for estimating the extent of the damaged region and observing the interface layer effectively. The difference of the ultrasonic reflection ratio between the bonding and debonding area at the interface layer is one of the key parameters for assessing the extent of the damaged area; additionally, the reflection amplitude exhibits a favorable correlation with the overall damage level. The technique developed in this study was applied to the inspection of the turbine bearings at several power plants in Korea whereby the applicability in the field can be ascertained.

• Journal of Sensor Science and Technology
• /
• v.24 no.6
• /
• pp.392-397
• /
• 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.

• Journal of the Korean Society of Food Culture
• /
• v.23 no.5
• /
• pp.572-581
• /
• 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.

• Journal of Soil and Groundwater Environment
• /
• v.25 no.4
• /
• pp.58-66
• /
• 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.

• Progress in Superconductivity and Cryogenics
• /
• v.19 no.2
• /
• pp.1-8
• /
• 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.