• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05b
• /
• pp.545-550
• /
• 1998

PWR 사용후핵연료 내에 존재하는 $^{134}$ Cs/$^{137}$Cs 및 $^{154}$ Eu/$^{137}$Cs의 감마선 핵종비를 써서 각각 연소도를 결정하고, 그들의 차이가 최소가 되는 시간을 찾는 방법으로 사용후핵연료의 냉각시간을 결정하였다. $^{134}$ Cs/$^{137}$ Cs 및 $^{154}$ Eu/$^{137}$Cs의 핵종비로부터 연소도를 구하는 방법은 이들 핵종비에 대한 ORIGEN-5 코드 계산과 감마스캐닝 실험 결과를 비교하는 것이었다$^{[1]}$ . 사용후핵연료의 냉각시간을 임의의 시간으로 가정하고 핵종비 $^{134}$ Cs/$^{137}$ Cs을 써서 구한 연소도와 $^{154}$ Eu/$^{137}$Cs를 써서 구한 연소도의 차이를 계산했으며, 이 차이는 실제 측정대상 핵연료의 냉각시간에서 최소가 될 것을 기대하였다. 감마선 방출 핵분열생성물인 $^{134}$ Cs와 $^{154}$ Eu는 비교적 긴 반감기를 갖고 있으면서도 또 이들의 반감기 차이가 약 6.4년이나 되므로 기존의 방법$^{[2]}$ 에 비해 넓은 범위의 냉각시간을 정확하게 측정할 수 있었다.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2010.10a
• /
• pp.43-45
• /
• 2010

Acquisition of thermoremanent magnetization follows a Boltzman statistics, as such long reaction time in a slowly cooled environment allows more chance to align individual magnetic particles parallel to the external magnetic field. Hence it has been proposed that the slowly cooled rocks often acquire stronger magnetization than the rapidly cooled ones. Such a proposition has been experimentally validated to be true for the fine-grained magnetite- or titanomagnetite bearing basaltic rocks collected from the mid-ocean ridges. However, the effect of cooling-rate on the remanence intensity appears to be insignificant for nominal grain ranges.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.31 no.4
• /
• pp.523-528
• /
• 1998

To clarify the effect of life or death condition before cooling on the physicochemical properties of plaice, Paralichthys olivaceus muscle at the early period after death, the plaices were dipped in the refrigerated sea water ($0^{\circ}C$) either as alive or after anesthesia killing. These samples were stored at $0^{\circ}C$ sea water and the changes in rigor-mortis, ATP breakdown, content of ATP and its related compounds, breaking strength and lactate accumulation through storage were investigated. Acceleration of rigor-mortis, ATP breakdown and lactate accumulation were taster in the samples refrigerated as alive than in samples killed by anesthesia before cooling. ATP in samples refrigerated as alive showed little breakdown until 7.5 hrs but it was decomposed completely after 17.5 hrs storage. The breaking strength in muscle of plaice was 1736.2 $\pm$ 65.4 g immediately after killing. The breaking strength in samples dipped in refrigerated sea water as alive increased more rapidly and showed the maximum value over 7.5 hrs (2183.3$\pm$32.2 g), However, in case of samples killed by anesthesia before cooling, the value and time reached around the maximum breaking strength were 2126.3 $\pm$ 32.2 g and 12.5 hrs, respectively and then decreased until 30 hrs. From these results, it could be suggested that dipping in refrigerated sea water after anesthesia killing before cooling is more effective in maintaining freshness of fresh plaice muscle than refrigerating as alive.

• Journal of the Microelectronics and Packaging Society
• /
• v.24 no.3
• /
• pp.41-46
• /
• 2017

In this study, rapid cooling method was proposed to improve the anti-scratch performance of anti-reflection film fabricated by nanoimprint lithography. Effects of cooling time on the mechanical properties and optical properties were evaluated. Pencil hardness measurements showed that anti-scratch performance enhanced as the cooling time increased while characterization on the optical property showed that reflectance on scratch increased as the cooling time increased. Therefore, it was concluded that the anti-scratch performance and optical properties are highly influenced by the cooling time. The observed results explained in terms of residual stress and free volume in polymeric materials.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.11
• /
• pp.432-436
• /
• 2016

The cooler, which is the main part in a Thermal Observation Device (TOD), makes the TOD function by reducing the temperature. As the cooler is imported, overseas enterprises presented 20,000 hours as the operation time and the military have used the cooler as presented. However, failures have occurred occasionally after mass production stage. Therefore, we need to analyze the MTBF of the TOD cooler. So, military and defense industry companies collected the failure data of the TOD cooler. We analyze the MTBF of the TOD cooler using survival probability function and failure data. We find the optimal distribution by applying parametric method and estimate parameters. We determine that the Log-logistic distribution is the most appropriate for this data. Also, we analyze the reliability per hour of the TOD cooler. The result of MTBF of the TOD cooler was higher than that of presented by oversee enterprises.

• Proceedings of the KAIS Fall Conference
• /
• 2006.11a
• /
• pp.261-264
• /
• 2006

본 논문에서는 다양한 곡률반경의 연속에 의하여 살 두께 차가 큰 사출성형품에 불균일한 수축으로 인한 변형이 생성되어 이를 방지하기 위한 적정 CAE 냉각설계를 수행하였다. SAN 및 PMMA 재질의 Jar용기에 대한 균일냉각구조와 최적성형조건을 금형설계에 적용하고자 사출성형의 중요인자인 사출압력, 수지온도, 금형온도, 냉각조건 등을 moldflow 프로그램을 활용하여 연구를 수행하였다. 연구결과로서, 적정 변수인 사출압력 상승, 수지온도 낮춤, 급속냉각으로 후로우 등의 불량현상을 분석하였고 변형 및 불량을 극소화시킬 수 있는 냉각구조와 사이클 시간을 단축시킬 수 있는 사출성형조건을 제시하였고 적정 냉각모듈로부터 냉각시간을 단축하였다.

• 기계와재료
• /
• v.23 no.3
• /
• pp.156-163
• /
• 2011

쥴톰순 냉동기는 스터링 냉동기, GM 냉동기, 스터링형 및 GM형 맥동관 냉동기 등 기계적 극저온냉동기에 비해 단순한 구조, 수 초의 급속한 냉각특성을 장점으로 중대형의 가스액화사이클 뿐만 아니라 적외선검출기의 급속냉각, 저온수술 등 다양한 분야에서 널리 사용되어지고 있다. 일반적으로 100K 이하의 작동온도 및 수 초 수준의 빠른 냉각을 요구하는 적외선검출기의 냉각을 위해서는 수 백기압 이상 고압의 질소 및 아르곤 가스를 사용하는 쥴톰슨 냉동기가 주로 사용되고 있다. 쥴톰슨 냉동기는 핀-관(fin-tube) 형태의 열교환기와 열교환기의 구조적 기반을 제공하는 멘드렐(mandrel), 쥴톰슨 노즐 등으로 구성되며, 열교환기의 열전달 성능 및 유량조절기구의 특성은 냉동기 저온부의 냉각온도, 냉각시간 및 운전시간에 큰 영향을 미친다.

• Journal of the Microelectronics and Packaging Society
• /
• v.5 no.2
• /
• pp.27-36
• /
• 1998

통신시스템의 고발열 전자부품 냉각을 위해 3종류의 써모싸이폰을 각각의 용도에 따라 개 발하였으며 그 각각의 설계변수에 대한 냉각특성을 실험적으로 구하였다. TS-I에서는 증발부 내부 에 금속스크린 메쉬형심지를 삽입함으로써 시간에 따른 온도 변화를 작게 하여 냉각성능 안정성을 확보하였고, TS-II에서는 9W/cm2의 높은 냉각성능을 가진 루프형 써모사이폰을 개발하였으며 TS-III에서는 작동유체의 종류, 파이프개수 와이어 삽입여부등 써모사이폰의 주요 설계변수에 따 른 냉각특성을 구하였다.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.242-242
• /
• 2003

DLC(Diamond-Like Carbon)는 높은 경도, 내마모성, 화학적 안정성, 생체친화성 및 열전도율이 우수하여 VTR 헤드드럼, CRT Gun, Video Tape, 인공골절, 면도날 등에 널리 사용되고 있다. 에어컨용 Al 냉각핀은 높은 냉각성능의 향상으로 인한 전기절전 효과와 내부식성 및 친수성 등이 요구된다. DC-Sputtering법에 의한 에어컨용 알루미늄 냉각핀에 인가전압의 변화 (300V, 500V, 600V)와 증착시간 (3시간, 5시간 증착)의 변화에 따른 DLC 박막을 합성하여 AFM, XRD 및 Raman spectroscopy 측정을 통하여 분석하고, Micro Vickers Hardness 및 Roughness 등을 측정하였다.

• Journal of the Korean Society of Radiology
• /
• v.16 no.4
• /
• pp.427-434
• /
• 2022

Atrial fibrillation treatment includes 3D RFCA and Cryo-balloon ablation. Both procedures have in common that they enter after understanding the structure of the heart using angiography equipment. Therefore, there is a disadvantage that the effect of exposure according to the procedure time can be a threat to both the patient and the operator, so this study aims to confirm the relationship between the total ablation time and the effect of radiation exposure. We used follow-up data (retrospective) from 41 patients who underwent coronary angiography and arrhythmia at the same time from March 2019 to July 2022. The range for total ablation time was based on the recorded data from the start to the end of the total ablation. The end point of 3D RFCA was when the ablation was completed for 4 pulmonary veins, and in the case of Cryo-balloon ablation, the data that succeeded in electrical insulation were included. As a result of analyzing the total ablation time, the time taken for Cryo-balloon ablation was 1037.29±103.66 s, which was 2448.61 s faster than 3D RFCA using 3485.9±405.71 s, and was statistically significant. (p<0.05) As a result of analyzing the total fluoroscopy time, the exposure time for 3D RFCA was 2573.75±239.08 s, which was less by 1717.15 s than the exposure time for Cryo-balloon ablation, 4290.9±420.42 s, and was statistically significant. In the case of total area dose product, 3D RFCA was 59.04±13.1 uGy/m², which was lower than Cryo-balloon ablation 980.6±658.07 uGy/m² by 921.56 uGy/m², which was statistically significant. As the insulation time of the Cryo-balloon ablation is shorter than that of the 3D RFCA, the method using the Cryo-balloon ablation is considered to be effective when the patient's condition is not good and a quick procedure is required. However, in patients with permanent Atrial fibrillation, there is a high probability of structural changes in the heart, so it is considered that 3D RFCA is better than Cryo-balloon ablation, which is difficult to manipulate.