• 방사성폐기물학회지
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• 제14권1호
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• pp.35-44
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• 2016

Leading national R&D project to design a PWR spent nuclear fuel interim dry storage system that has been under development since mid-2009, which consists of a dual purpose metal cask and concrete storage cask. To ensure the safe operation of dry storage systems in foreign countries, major confinement monitoring techniques currently consist of pressure and temperature measurement. In the case of a dual purpose metal cask, a pressure sensor is installed in the interspace of bolted double lid(primary and secondary lid) in order to measure pressure. A concrete storage cask is a canister based system made of double/redundant welded lid to ensure confinement integrity. For this reason, confinement monitoring method is real time temperature measurement by thermocouple placed in the air flow(air intake and exit) of the concrete structure(over pack and module). The use of various monitoring technologies and operating experiences for the interim dry storage system over the last decades in foreign countries were analyzed. On the basis of the analysis above, development of the confinement monitoring technology that can be used optimally in our system will be available in the near future.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.55-68
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• 1995

Approximately 30 to 70 % of the mechanical losses in a reciprocating engine are contributed by the friction at the piston ring-cylinder interface. The friction characteristics of the piston ring during engine operation is known to as mixed lubrication experimentally. The mixed lubrication models based on the Average Reynolds Equation have been used by this time in order to study the tribological performance of the ring. However, the Average Reynolds Equation contains the expected value term(${\bar{h}}_r$) of local film thickness as well as nominal film thickness(h), so that the work of numerically solving ${\bar{h}}_r$ must be included to obtain the pressure in the oil film. The process of solving ${\bar{h}}_T$ causes a greater multiplying in the numerical solution. In this paper the mixed lubrication analysis using the Simplified Average Reynolds Equation in the piston ring is presented. This equation has only h as oil film thickness term. Therefore the tedious numerical procedure required to obtain ${\bar{h}}_T$ is not needed, and also, computation time can be reduced.

• Elastomers and Composites
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• 제38권2호
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• pp.128-138
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• 2003

폐타이어의 증가로 인하여 환경문제가 날로 심각해지고 있다. 그러므로 효율적인 재활용을 통하여 이러한 문제를 해결하는데 많은 연구가 진행되고 있다. 본 연구에서는 폐타이어를 상온분쇄기를 제작하여 미세 분말화와 초음파로 처리를 통하여 기본물성을 높이는데 목적을 두었다. 폐고무 분말의 통계학적 분석에 의해서 미세화에 따른 물성의 변화와 물리적 성질을 조사하였고, 기계적 및 가교도 등의 물성을 조사하였다. 또한 광학현미경을 사용하여 표면을 확인함으로서 제품특성을 연구하였다.

• International Journal of Aerospace System Engineering
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• 제3권2호
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• pp.22-25
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• 2016

This dissertation tried to analyze passenger behaviors after an accident with the possibilities of a variety of accidents open reflecting the phases of the times of increasing interests in safety of passengers as the use of means of transportation such as cars and airplanes is increasing. Because a lot of data on head-on collisions, broadside collisions and reverse side collisions have been gathered through lots of experiments and interpretations, I chose to study a relatively unfamiliar subject, dropping collision. For example, I tried to study passenger behaviors in seating position after a dropping collision in preparation for falling accidents due to recent frequently-occurring sinkholes, driver's carelessness or mechanical problems. I used MADYMO, passenger behavior interpretation program, and experimented with 2 meters high Drop Test device which I made in person to increase the reliability of the results. On the basis of these, I compared the real experiments with interpretations.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.745-745
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• 2002

Both geophysical and geospatial data provide important information in the establishment of the optimal telecommunication systems especially in the mobile telecommunication environment. The objective of this study is to utilize geophysical properties and geospatial information in the analysis of the telecommunication environment through point-to-point wave property modeling. Geophysical properties associated with wave propagation parameters of the earth surface were analyzed based on hierarchical land classification using Landsat ETM＋ and IKONOS images. Three-dimensional geospatial information was obtained by processing stereo aerial images. The results show that the accurate geospatial information and reliable geosphysical property of the surface improve the prediction of receiving power of the receivers located near corners of the buildings where diffractions occur. The wave property model developed from accurate telecommunication environment could be applied to optimal cell planning and delay time analysis.

• 한국지열·수열에너지학회논문집
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• 제17권4호
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• pp.46-58
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• 2021

As accidents with thermal runaway (TR) of lithium-ion batteries occur sporadically, the safety concern is the main obstacle that hinders the large-scale applications of lithium ion batteries. In most accidents, the TR of a single cell occurred first, and then dissipated the heat to the surroundings and triggered the TR of adjacent cells, resulting in TR propagation. Therefore, it is important to understand the mechanism of TR propagation and determine the key parameters during TR propagation in a battery pack. In this study, we performed a numerical analysis on the thermal runaway phenomenon by cathode active materials and appearance sizes in cylindrical lithium-ion batteries using a two-dimensional analysis model. The model results showed that the TR propagation of 21700 type cells (21 mm diameter, 70 mm height) occurs more rapidly than 46800 type cells (46 mm diameter, 80 mm height) and the LFP cell has higher thermal safety than the NCM cell. Especially, we found that the effect of the separator on the occurrence of TR is negligible.

• 한국염색가공학회지
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• 제34권3호
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• pp.197-206
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• 2022

The purpose of this study was to confirm the optimal spinning conditions for PLA (Polylactic acid) as a fiber forming polymer. According to the melt spinning test results of PLA, the optimal spinning temperature was 258℃. However, it needs to note that relatively high pack pressure was required for spinning at 258℃. At an elevated temperature, 262℃, mono filament was broken easily due to hydrolysis of PLA at a higher temperature. In case of fiber strength, it was confirmed that the draw ratios of 2.7 to 3.3 were optimal for maximum strength of melt spun PLA. Above the draw ratio, 3.3, the strength of the PLA fibers was lowered. It was presumed that cleavage of the PLA polymer chain over maximum elongation. The heat setting temperature of GR (Godet roller) showed that the maximum strength of the PLA fibers was revealed around 100℃. The degree of crystallinity and the strength of the PLA fibers were decreased above 100℃. The optimal take-up speed (Spinning speed) was around 4,000m/min. Thermal analysis of PLA showed 170℃ and 57℃ as Tm (melting temperature) and Tg (glass transition temperature), respectively.

• 한국기계가공학회지
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• 제21권6호
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• pp.44-49
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• 2022

The improvement in the battery performance and life using a battery thermal management system directly affects the improvement in the performance, life, and energy efficiency of electric vehicles. Therefore, this study numerically analyzed the heat exchange processes between the coolant inside the cooling plate channel and the heat generated by the battery. The cooling performance was analyzed based on the average temperature, temperature uniformity, and the maximum and minimum temperature differences of the battery. A performance difference existed depending on the coolant inlet temperature but showed the same tendency of cooling performance according to the shape of each plate's channel. Type 1 showed the best results in terms of battery temperature uniformity, which is the most important measure of battery performance; Type 2 showed the best results in terms of the average temperature of the battery; and Type 3 showed the best results in terms of the maximum and minimum temperature differences of the battery compared with that of the other cooling plates.

• 한국추진공학회지
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• 제26권3호
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• pp.1-9
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• 2022

본 연구에서 대상으로 삼은 비행체는 4~5인승급 수직이착륙기이며, 해당 비행체용 추진시스템은 가스터빈엔진과 배터리팩을 주 전력원으로 사용하여 다수의 모터가 필요로 하는 요구전력을 공급하는 분산 하이브리드 추진시스템이다. 본 연구에서는 기본설계 결과를 바탕으로 MATLAB/Simulink 프로그램을 사용하여 하이브리드 추진시스템용 설계/해석 플랫폼을 개발하였다. 시뮬레이션 해석을 통해 비행 시나리오에 따른 각 전력원별 출력 거동 및 운용 범위를 확인하였고, 이를 통해 기본설계 결과의 실현가능성을 확인하였다.

• 한국가시화정보학회지
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• 제21권2호
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• pp.34-45
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• 2023

When lithium-ion batteries operate out of the proper temperature range, their performance can be significantly degraded and safety issues such as thermal runaway can occur. Therefore, battery thermal management systems are widely researched to maintain the temperature of Li-ion battery cells within the proper temperature range during the charging and discharging process. This study investigates the cooling performance and isothermal maintenance of cooling materials by measuring the surface temperature of a battery cell with or without cooling materials, such as silicone oil, thermal adhesive, and phase change materials during discharge process of battery by the experimental and numerical analysis. As a result of the experiment, the battery pack filled with phase change material showed a temperature reduction of 47.4 ℃ compared to the case of natural convection. It proves the advanced utility of the cooling unit using phase change material that is suitable for use in battery thermal management systems.