• Design & Manufacturing
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• 제15권1호
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• pp.26-31
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• 2021

As the aging ages, the disease also increases, and the development of AI technology and X-ray equipment used to treat patients' diseases is also progressing a lot. X-ray tube converts only 1% of electron energy into X-ray and 99% into thermal energy. Therefore, when the cooling time of the anode and the X-ray tube are frequently used in large hospitals, the amount of X-ray emission increases due to temperature rise, the image quality deteriorates due to the difference in X-ray dose, and the lifespan of the overheated X-ray tube may be shortened. Therefore, in this study, temperature rise and cooling time of 60kW, 75kW, and 90kW of X-ray tube anode input power were studied. In the X-ray Tube One shot 0.1s, the section where the temperature rises fastest is 0.03s from 0s, and it is judged that the temperature has risen by more than 50%. The section in which the temperature drop changes most rapidly at 20 seconds of cooling time for the X-ray tube is 0.1 seconds to 0.2 seconds, and it is judged that a high temperature drop of about 65% or more has occurred. After 20 seconds of cooling time from 0 seconds to 0.1 seconds of the X-ray tube, the temperature is expected to rise by more than 3.7% from the beginning. In particular, since 90kW can be damaged by thermal shock at high temperatures, it is necessary to increase the surface area of the anode or to require an efficient cooling system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.15-19
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• 2002

With the rapid development of industrial technologies, the demand for high precision products has been increasing drastically. For this reason, the need for developing of high performance machine tool, which can ensure high precision, is desired in the industrial fields. Technologies on the spindle system manufacture, guideway manufacture, error compensation, design of bed structure, protection against vibrations, and system integration are core technology for developing of high precision machine tools. Especially, among these, design of spindle system, which is leading precision and manufacturing technique. is one of the most important technologies. A high speed and high precision spindle system, which will be used for final machining of ferrule, is designed considering the effect caused by thermal, cutting torque, cutting farce, and work-piece materials. The detail process of analysis is presented.

• 한국가스학회지
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• 제9권1호
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• pp.1-8
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• 2005

본 연구에서는 $9\%$ 니켈강재식 LNG저장탱크에 대한 누설 안전성을 여러 가지 단열재와 코너 프로텍션, PC 구조물 사이에 존재하는 열저항 평형온도 효과를 고려하여 유한요소법으로 해석하였다. FEM 계산결과에 따르면, 파이버 글라스 블랑켓, 펄라이트 파우더, 셀루러 글라스 단열재 등은 재질의 취약한 강도 때문에 누설 LNG에 의한 하중이 가해지면 단열재 자체가 파손되므로 누설 안전성을 보장할 수 없게 된다. 그러나, 내부탱크와 단열재가 동시에 파손되어도 $9\%$ 니켈강재로 제작된 코너 프로텍션(CP) 예응력 콘크리트(PC)구조물의 외부탱크는 LNG의 복합하중에 대하여 강도 안전성을 확보하고 있으므로, 누설 LNG를 최소한 10일 정도는 안전하게 체류시킬 수 있다. 따라서, $9\%$ 니켈강제식 LNG 저장탱크 시스템은 이들 두 가지 구조물에 의해 누설 안전성이 확보된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2219_2220
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• 2009

The characteristics of the Superconducting Magnetic Energy Storage (SMES) system are faster response, longer life time, more economical, and environment friendly than other Uninterruptible Power Supply (UPS) using battery. Fast charge and discharge time of SMES system can provide powerful performance of improving power quality in the grid. In order to demonstrate the effectiveness of SMES, the authors make a 10kJ SMES system for connection with RTDS (Real Time Digital Simulator). Because the characteristics of superconducting magnet are very important in SMES system, the necessary items such as thermal characteristic, mechanical stress and protection circuit should be considered. In this paper, the authors experimented thermal characteristics of the 10kJ SMES system. The experiment was accomplished using a simulation coils made of aluminium. It has same dimension of the 10kJ class HTS SMES coil. The coil was cooled with GM (Gifford -McMahon) cryocooler through the OFHC (Oxgen Free High thermal Conductivity) conduction bar. The test results of cool down and heat loads characteristics of the simulation coils are described in detail.

• 한국산학기술학회논문지
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• 제12권8호
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• pp.3353-3359
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• 2011

본 연구에서는 가스터빈과 증기터빈, 열회수증기 발생 장치와 지역난방 열교환기로 열병합 발전 시스템을 구성하여 복수기가 없이 증기 터빈 중압단에서 추기된 증기와 배기 증기를 지역난방 열교환기의 열원으로 사용하는 추기 배압식을 적용하였다. 구성된 시스템에 대하여 필요로 하는 열부하량과 발전 출력 조건을 만족 시키기 위한 최적 설계 성능 해석을 하였으며, 이와 함께 겨울철 외기 온도 조건의 변화에 대한 시스템의 부분부하 해석을 하였다. 해석을 위해 상용 프로그램인 Thermoflex를 사용하였다. 시스템의 해석 결과, 기준 조건에서 수요처의 요구를 만족 시키는 최적 설계를 기준으로 각 외기 온도 변화에 대한 부분부하 성능 해석의 결과를 얻을 수 있었다. 그 결과 열부하량이 고정된 상태에서, 가스터빈과 전체 시스템의 출력은 외기온도가 감소함에 따라서 증가하였지만, 열원인 배기가스의 온도 감소로 인하여 증기터빈의 출력은 이와 반대로 감소하는 경향을 나타내었다. 그러나 전체 시스템에서 가스터빈의 차지하는 비중이 크기 때문에 전체 시스템의 출력의 경향은 가스터빈과 동일한 결과를 얻을 수 있었다.

• 설비공학논문집
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• 제30권1호
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• pp.10-16
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• 2018

The climate of summer in Korea is quite hot and humid. Many studies have been carried out to reduce the energy required for operating a dehumidifier. The dehumidifier is mainly connected to the cooling system since it operates in the summer. Conventional dehumidification methods often require additional cooling and energy for dehumidification. In this study, a system for increasing the efficiency by applying a membrane was analyzed. Its energy saving effect was analyzed when it was applied to residential buildings. Economic efficiency was also evaluated. As a result of this study, 9.0% energy savings were achieved for residential buildings. The investment recovery period was 28.9 years. Such long investment recovery period was because the initial investment cost was excessive and annual energy saving only appeared in the summer.

• KIEAE Journal
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• 제16권1호
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• pp.21-28
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• 2016

Purpose: The purpose of this study is to analyze & suggest the variation of energy consumption consequent on thermal insulation performance strengthening from early 2000s when modernization of barracks began until the present targeting a large barracks. Method: To carry out this research, this study surveyed the standard of thermal insulation by year, which is being applied to a barracks by conducting literature search, and selected the standard model for a barracks. Also, this study analyzed energy consumption by year & region by performing simulation(ECO2)of the selected standard model. Result: As a result, it was analyzed that in case of a building which was completed in 2015, the energy consumption for air-conditioning & heating, lighting, and hot water supply over the year 2000 reduced by 11% on the average in central district, 10% on the average in southern district, and 17% on the average in Jeju, respectively.

• 한국군사과학기술학회지
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• 제21권1호
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• pp.69-73
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• 2018

Korean-peacekeeper's transparent armors in Iraq showed delamination, cracking and clouding a decade ago. And there were also similar deterioration recurrences in KLTV during the operational test a few years ago. Also, the differences between operational capability & lab Bullet-proof test condition, and insufficiency of military protection spec resulted in incomplete bullet-proof results. Moreover, although so many ground weapon systems have been developed, there were not secure test & evaluation codes to verify transparent armoured glasses equal to advanced-overseas products. So in this study, first, environmental test codes were established that all tests should be carried out as the application of only one specimen with newly adopted thermal shock test instead of completing each test with different one. Second, protection standards were integrated through the analysis of global developed country's specifications and reinforced as adding to the real mock-up condition if vehicle's glasses are smaller than standard specimen. Hereby, by applying to test-codes which including actual operational & vehicular conditions, the gap between development test and operational environment was minimized.

• 한국화재소방학회논문지
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• 제30권2호
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• pp.19-26
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• 2016

본 논문은 국내 주요 시설 및 국가 기반 시설로 변화되고 있는 터널 및 지하 공동구의 조기화재탐지설비시스템 설치에 이용되고 있는 광센서 선형 화재 감지 시스템에 대한 특성 분석을 목적으로 연구를 수행하였다. 연구 방법으로는 저온 환경인 $-20^{\circ}C$에서 5일간 5가지의 열감지기 중에서 작동 여부를 확인한 결과 광센서 선형 감지기만 작동하는 것을 알 수 있었다. 또한 터널과 같은 풍속이 발생되는 곳을 가정하여 축소 모형 터널을 제작하여 0 m/s와 1 m/s를 변수로 하여 광센서 선형 감지기의 작동 특성을 분석하였다. 그 결과로서 광센서 선형 감지 시스템의 온도 변화에 있어서는 풍속이 없을 때인 0 m/s 때의 값이 높게 나타나는 것을 알 수 있었다.

• 한국안전학회지
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• 제10권3호
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• pp.96-105
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• 1995

The better industry develops, the more spaces need but in the limited area. Most building become larger and more complicated if the more spaces need in the constant area. And this leads to do underground work in long period generally six(6) months for 6 basement stories due to the selection of TOP DOWN technique. Working environment in this underground area can be problems and should not be overlooked, because air quality in underground spaces become quickly worse. Recently, department name to control construction safety has been changed to ENVIRONMENT & SAFETY TEAM from SAFETY TEAM. This means that it is very important to control against environmental condition at site so much. Overall construction work as well as underground work should conform to the requirement of working environment, particularly against inhabitants around the construction area. Strut protection, one of earth protection method, in case to 40m long strut may become weaker due to thermal stress or its longitudinally compressive strain and the another one, earth anchor protection may not be applied to the site In case of encroaching on vertical underground borderline because of regulation to prohibit it. It is necessary that TOP DOWN technique should be introduced in order to solve the external and internal problem of the site such as difficulty level of the work, potential danger with excavating depth, and shortening workperiod. It is needed that improving way of working condition should be shown and simplified computer simulation program should be also provided for checking pollution level & ventilation, excluding of lighting problem here. Results measured with conformance to the Regulation for Working Environment Measurement, enforced by Ministry of Labor have been applied to the computer program developed here. Sample air taken at unit workplace which was considered as exposing condition of pollutant at breathing point and within a range of behavior of the workers, Identified exposing group in underground work, using Moded Flow Life Finally, three types of ventilation system, type I with blower & ventilator, type II natural supply with mechanical ventilation system, and type I mechanical ventilation with Drivent Fan Unit System are selected for this study.