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전의식,서순봉 대한피부과학회 1974 大韓皮膚科學會誌 Vol.12 No.4
Roots of manually extracted scalp hairs among 86 healthy Koreans in different age groups were examined microscopically and the proportion of resting hairs to growing hairs were determined with the followings results. 1. The proportion of resting hairs in all age groups was 10.9% and there was no significant difference between male and female. 2. In each age group the proportion of resting hairs shows difference, being lowest(6.8%) in below 9 years age group, increasing the rate by increasing the age group, highest(19.7%) in over 60 years age group. 3. The proportion of resting hairs below the age of 29 years was below 10%, above 30 years to 49 years in between 10% to 15%, and over 50 years in between 15% to 20%. 4. The normal range of the proportion of resting hairs among normal Koreans was below 20%.
몰드 두께에 의한 팬 아웃 웨이퍼 레벨 패키지의 Warpage 분석
전의식,문승준,김재경 한국반도체디스플레이기술학회 2023 반도체디스플레이기술학회지 Vol.22 No.4
Recently, fan out wafer level packaging, which enables high integration, miniaturization, and low cost, is being rapidly applied in the semiconductor industry. In particular, FOWLP is attracting attention in the mobile and Internet of Things fields, and is recognized as a core technology that will lead to technological advancements such as 5G, self-driving cars, and artificial intelligence in the future. However, as chip density and package size within the package increase, FOWLP warpage is emerging as a major problem. These problems have a direct impact on the reliability and electrical performance of semiconductor products, and in particular, cause defects such as vacuum leakage in the manufacturing process or lack of focus in the photolithography process, so technical demands for solving them are increasing. In this paper, warpage simulation according to the thickness of FOWLP material was performed using finite element analysis. The thickness range was based on the history of similar packages, and as a factor causing warpage, the curing temperature of the materials undergoing the curing process was applied and the difference in deformation due to the difference in thermal expansion coefficient between materials was used. At this time, the stacking order was reflected to reproduce warpage behavior similar to reality. After performing finite element analysis, the influence of each variable on causing warpage was defined, and based on this, it was confirmed that warpage was controlled as intended through design modifications.
TiN이 코팅된 316 스테인리스강 분리판을 이용한 1 kW 급 고분자 전해질 연료전지 스택의 운전특성
전의식,조은애,하흥용,홍성안,오인환 한국수소및신에너지학회 2004 한국수소 및 신에너지학회논문집 Vol.15 No.1
A 12-cell PEMFC stack was fabricated using the TiN-coated 316 stainless steel bipolar plates as substitute for the expensive and brittle graphite bipolar plates. Open cirtuit voltage and the maximum power of the stack was 12.08 V and 1.197 kW (199.5 A @ 6 V), respectively. Volumetric and gravimetric power density of the stack was calculated to be 373 W/L and 168 W/kg, respectively. Performance of each cell was quite uniform initially while degraded at a singnificantly different rate. During the 1,000 hr-operation at a constant load of 48 A, stack voltage decreased from 9.0 to 7.98 V at a degradation rate of 11 %/1,000 hr. However, degradation rate of each cell was in the wide rage from 1.2 to 31 %/1,000 hr.
건축물(建築物) Elevator의 방진(防振)을 위한 진동특성(振動特性) 분석(分析)
전의식,조병후,Jeon, Euy-Sik,Cho, Byoung-Hoo 한국디지털건축·인테리어학회 2005 한국디지털건축인테리어학회 논문집 Vol.5 No.2
The interest about noise and vibration which occurs in buildings is increasing by a living level elevation recently. Particularly, the vibration which occurs from the elevator cage of the building is possibility of damage to the users of the building continuously. So, the purpose of this study is a place where it examines closely the vibrating unit of the elevator and propose the countermeasure of it.
전의식,조병후,Jeon, Euy-Sik,Cho, Byoung-Hoo 한국디지털건축·인테리어학회 2003 한국디지털건축인테리어학회 논문집 Vol.3 No.1
The interest about noise and vibration is increasing by a living level elevation recently. Particularly, the interest about the influence that vibration of machine has on the safety of building is rising. However, there are a lot of the cases that the influence of machine isn't considered in designing the factory buildings. The purpose of this study is to suggest the results of measuring that the influence of machine's vibration in A factory has on the building structure.