• Steel and Composite Structures
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• 제48권6호
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• pp.641-648
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• 2023

In this article, we explore the issue concerning semiconductors half-space comprised of materials with varying thermal conductivity. The problem is within the framework of the generalized thermoelastic model under one thermal relaxation time. The half-boundary space's plane is considered to be traction free and is subjected to a thermal shock. The material is supposed to have a temperature-dependent thermal conductivity. The numerical solutions to the problem are achieved using the finite element approach. To find the analytical solution to the linear problem, the eigenvalue approach is used with the Laplace transform. Neglecting the new parameter allows for comparisons between numerical findings and analytical solutions. This facilitates an examination of the physical quantities in the numerical solutions, ensuring the accuracy of the proposed approach.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.103-104
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• 2022

Cracks may occur in reinforced concrete (RC) structures due to various physical and chemical factors, and the growth of cracks causes deterioration of the structure's performance. It is important to prevent the expansion of cracks through periodic diagnosis of cracks in structures. In order to enable free crack exploration even in a narrow space, a construction robot using a Mecanum wheel that can move up, down, left and right and rotate in place was designed. High-quality crack images were periodically collected through the camera, and the image fragments stored during the exploration were combined into a single photo after the exploration was completed. The robot detected cracks with a width of 0.2 mm or more on the concrete probe surface with an accuracy of about 90% or more.

• 천문학회보
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• 제46권1호
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• pp.56.1-56.1
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• 2021

Identifying the main source of reionization is one of the essential astrophysical problems that remain to be solved. But there are difficulties in directly measuring the Lyman continuum (LyC) escape fraction (fesc) from high-z galaxies, and other indirect methods have been suggested to identify potential LyC leakers. The O32 ratio ([OIII] λ5007 / [OII] λ3727) is one of those examples, which appear to positively correlate with fesc according to some observations and photoionization modelling of HII regions. However, recent studies fail to find such a correlation. Here we exploit a set of radiation-hydrodynamic simulations of giant molecular clouds to understand the physical connection between O32 and fesc. We post-process our simulations with the photo-ionization code Cloudy, and discuss the results obtained from the runs with different metallicities and input SEDs.

• 전기화학회지
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• 제11권2호
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• pp.100-104
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• 2008

Titanium sheet metal substrates used in thin film batteries were wet etched and their surface area was increased in order to increase the discharge capacity and power density of the batteries. To obtain a homogeneous etching pattern, we used a conventional photolithographic process. Homogeneous hemisphere-shaped wells with a diameter of approximately $40\;{\mu}m$ were formed on the surface of the Ti substrate using a photo-etching process with a $20\;{\mu}m{\times}20\;{\mu}m$ square patterned photo mask. All-solid-state thin film cells composed of a Li/Lithium phosphorous oxynitride (Lipon)/$LiCoO_2$ system were fabricated onto the wet etched substrate using a physical vapor deposition method and their performances were compared with those of the cells on a bare substrate. It was found that the discharge capacity of the cells fabricated on wet etched Ti substrate increased by ca. 25% compared to that of the cell fabricated on bare one. High discharge rate was also able to be obtained through the reduction in the internal resistance. However, the cells fabricated on the wet etched substrate exhibited a higher degradation rate with charge-discharge cycling due to the nonuniform step coverage of the thin films, while the cells on the bare substrate demonstrated a good cycling performance.

• 조명전기설비학회논문지
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• 제16권1호
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• pp.35-43
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• 2002

새로운 형태의 고체 상태의 대전력, 고속전자장치인 광전도 전력스위치(PCPS)의 개발과 대전력 및 고전압 상태하에서 광전도 전력스위치의 고전계 동작특성을 규명하기 위해서 많은 연구가 행해지고 있다. 그러나 표면 섬락 현상이 확실하고 효과 있는 고속, 고압스위칭 소자의 실현을 방해하고 있다. 이러한 연면방전의 물리적 현상의 명백한 이해는 새로운 기술과 소자구성을 발전시키는데 매우 중요할 뿐 아니라, 고전계·고전압에서의 동작특성을 향상시키는데 있어서도 특별한 의미를 가진다. 뿐만 아니라 고전계, 고전력 소자들을 안전하게 동작할 수 있게 하기 위해서도 필요하다. 연면방전 및 표면 절연파괴현상은 반도체 벌크 파괴 전계보다 훨씬 낮은 전계에서 적용되어 파괴된 모든 소자들에서 발생하기 때문에 이러한 문제를 해결하는 매우 실용적인 방법이 소자의 표면을 절연물로 페시베이션하는 것이다. 페시베이션된 소자들은 고전계에서 언페시페이션된 소자에 비해 매우 좋은 동작특성을 나타내므로, 본 논문에서는 페시베이션된 소자와 언페시베이션된 소자간의 I-E특성과 파괴 메커니즘을 규명하고 더 나아가 다중 페시베이션에 대한 몇몇 특성 값을 제시한다.

• 한국해양환경ㆍ에너지학회지
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• 제12권1호
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• pp.55-59
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• 2009

중소형 폐 선박으로부터 생성되는 FRP를 재활용하기 위한 방법으로 층상으로 배열된 로빙층과 매트층을 분리하는 것은 에너지 면에서나 환경적인 면에서 많은 장점을 가지고 있다. 비록 로빙층과 매트층은 그 비율은 다르나 모두 수지와 유리를 포함한다는 유사성과 로빙층은 매트층에 비해 얇은 두께로 존재한다는 이유로 인해 로빙층을 매트층과 분리할 때 기계가 자동적으로 충간의 차이를 인식하기는 어렵다. 본 연구에서는 유리의 구성비가 다른 두 층의 화학적 성질의 차를 이용하여 광학적으로 층간 인식이 가능한 방법을 모색하였다. FRP에 대해 (1) FRP의 층 사이에 존재하는 수지를 녹이는 진한 황산, 또는 (2) 유리를 녹이는 염기성 용액(KOH의 메탄올과 아이소프로판올 용액), (3) 유리의 $SiO_2$와 반응하는 플루오르산(HF)용액, (4) HF 용액으로 처리한 후 수용성 염료를 도포한 경우, 각각 두 층간의 차별화가 일어났다. 이 결과를 이용하여 폐 FRP의 분리 공정이 단순화될 수 있을 것이다.

• Food Science and Biotechnology
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• 제15권1호
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• pp.5-12
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• 2006

Degradation performance of environmentally friendly plastics that can be disintegrated by combination of sunlight, microbes in soil, and heat produced in landfills was evaluated for use in industries. Two multi-degradable master batches (MCC-101 and MCC-102 were manufactured, separately mixed with polyethylene using film molding machine to produce 0.025 mm thick films, and exposed to sunlight, microbes, and heat. Low- and high-density polyethylene (LDPE and HDPE) films containing MCC-101 and MCC-102 became unfunctional by increasing severe cleavage at the surface and showed high reduction in elongation after 40 days of exposure to ultraviolet light. LDPE and HDPE films showed significant physical degradation after 100 and 120 days, respectively, of incubation at $68{\pm}2^{\circ}C$. SEM images of films cultured in mixed mold spore suspension at $30^{\circ}C$ and 85% humidity for 30 days revealed accelerated biodegradation on film surfaces by the action of microbes. LDPE films containing MCC-l01 showed absorption of carbonyls, photo-sensitive sites, at $1710\;cm${-1}$ when exposed to light for 40 days, whereas those not exposed to ultraviolet light showed no absorption at the same frequency. MCC-101-based LDPE films showed much lower $M_w$ distribution after exposure to UV than its counterpart, due to agents accelerating photo-degradation contained in MCC-101.

• 한국응용과학기술학회지
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• 제36권1호
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• pp.305-311
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• 2019

높은 함수율을 갖는 소프트렌즈를 제조하기 위하여 아크릴계 공중합체를 설계, 제조하였다. 공중합체용 모노머로 2-hydroxyethyl methacrylate(HEMA)를 사용하였고 가교제로는 ethylene glycol dimethacrylate(EGDMA), glycerol dimethacrylate(GD) 혹은 glycerol 1,3-diglycerolate diacrylate(GDD)를 이용하여 렌즈를 제조하였다. 함수율 측정결과, 고함수율 렌즈는 기존의 36%에서 46%로 높게 나타났으며 접촉각도 38.6 에서 34.4 로 낮아져 표면 친수성이 높게 나타남을 확인하였다. 인장강도는 가교제의 친수성이 증가함에 따라 0.1MPa 에서 0.08 그리고 0.05 로 감소하였고 전자현미경으로 렌즈의 단면을 확인한 결과 상분리 현상은 나타나지 않았다. 광중합은 Real-time infrared(RTIR)로 측정하였는데 초기 중합 속도가 가교제에 따라 0.6 에서 0.9 로 나타났다.

• 한국환경보건학회지
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• 제20권4호
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• pp.98-117
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• 1994

To provide data for the contents regarding environmental health (environmental hygiene, environmental pollution) in the textbooks of primary, middle and high schools, a total of 243 textbooks was analysed for two months from May, to July 31, 1993. Among the total 52844.50 pages, 1.65% was related to the environmental health, which account for 870.00 pages. In the textbooks by school level, the rate of the contents regarding environmental health in primary school was 1.63% (148.75 pages). that of middle school was 1.96% (243.25 pages) and that of high school was 1.53% (478.00 pages). The area of environmental hygiene was 0.24% (129.25 pages) and that of environmental pollution was 1.40% (740.75 pages) which is slightly high. In the field of environmental hygiene, the rate of the contents in the middle school textbooks was 0.53% which was the higher than that of the primary and high school textbooks. The rate of environmental pollution area was not significantly different by school level but the number of the pages was the higher at the high school than that of the primary and middle schools, which account for 428.8 pages. The contents related by the areas were as follows: 1. Contents related to environmental hygiene 1) Among environemtnal hygiene contents, the rate of housing sanitation was the highest as 0.14% (73.00 pages), that of air environment was 0.06% (33.00 pages) and that of water supply sanitation was 0.03% (17.25 pages). The portion of air environment was 5.00 pages in the primary school textbooks and that of housing sanitation at the middle and high schools was each 35.0 pages, 35.50 pages, which was the more than that of other fields. By school year, there was no contents related at the 1st and 2nd grades but were 4.75 pages at the 4th grade which were the more than those of other grades. At the 5th grade, water supply sanitation part was found but not air environment. Housing sanitation was found at the 3rd, 5th grades and insect or rodent control was at the 3rd, 4th, 5th, 6th grades. 2) In the middle school textbooks related to environmental health, 41.0 pages were included in the textbooks of pysical education, the highest number. The next was 19.5 pages in home economics, 2.8 pages in social studies and 3.00 pages in others. The contents of air environment were found in the textbooks of physical education and science, those of water supply and housing sanitation were in home economics and physical education and those of insect control were found 0.5 pages in home economics only. 3) In the high school textbooks, the highest number was 27.8 pages of home economics and the next was 11.5 pages of others, 7.8 pages of physical education, 2.0 pages of science and 0.3 pages of social studies. Air environment parts were included in the textbooks of science, physical education and home economics and water sanitation was in home economics, physical education and others. Housing sanitation was showed in home economics and social studies, on the other side the contents of insect or rodent control was found in home economics and physical education. 4) By the subjects related to environmental hygiene in the primary, middle and high school textbooks, 51.0 pages of home economics were the highest portion. It was also revealed that 49.5 pages of physical education, 14.5 pages of others, 13.5 pages of science and 0.8 pages of social studies were included. The number of 33.0 pages of air environment portion was distributed into 9.75 pages of science, 19.0 pages of physical education and 4.25 pages of others. Among 17.3 pages of water sanitation, 3.5 pages of home economics, 11.3 pages of physical education and 2.5 pages of others were included. Housing sanitation portions were 73.0 pages, which were distributed into 46.5 pages of home economics, 0.5 pages of social studies, 18.3 pages of physical education and 7.8 pages of others. 5) The number of photo, figure, illustration and table related in the primary school textbooks was 31. Among them, the number of photos was 21, that of figures or illustrations was 9 and that of table was 1. The number of 63 in the middle school textbooks was classified into 3 photos, 32 figures or illustrations and 28 tables. At the high school, the number of 56 was included 2 photos, 41 figures or illustrations and 13 tables.2. Contents related to environmental pollution 1) In the field of environmental pollution, the rate of water pollution was 0.39% (203.3 pages), that of air pollution was 0.31% (161.5 pages) that of soil pollution was 0.1% (57.3 pages), that of refuse disposal was 0.08% (40.3 pages) and others was 0.5% (278.5 pages) by school level, the rate of water pollution in the primary, middle and high schools was each 40.5, 48.0, 118.8 pages and that of air pollution was each 20.8, 38.3, 102.5 pages. 2) Environmental pollution areas were not inserted in the textbooks at the 1st grade of the primary school but foqnd 5.5 pages at the 2nd grade, 30.5 pages at the 4th grade, 36.3 pages at the 5th grade and a,9.5 pages at the 6th grade. Water pollution was included from the 2nd grade, air pollution and refuse disposal from the 3rd grade and soil pollution from the 5th grade. 3) In the middle school textbooks, environmental pollution was distributed into 90.25 pages of science, 42.8. pages of physical education, 20.5 pages of social studies, 19.5 pages of others and 4.0 pages of home economics. At the high school, the contents were found 191.3 pages in science, 119.3 pages in others, 88.5 pages in social studies, 28.5 pages in physical education and 1.3 pages in home economics. 4) By subjects of the primary, middle and high schools, the portion of environmental pollution was classified into 322.2 pages of science, 195.0 pages of social studies, 138.8 pages of others, 76.3 pages of physical education and 8.5 pages of home economics. Air and soil pollution parts were not found in the subjects of home economics. 5) The number of photo, figure or illustration and table related in the primary school textbooks was 218. Among them, the number of photos was 61, that of figures or illustrations was 149 and that of tables was 8. At the middike school, the number of 153 was distributed into 99 photos, 34 figures or illustrations and 20 tables. The number of 129 found in the high school textbooks was included 129 photos, 73 figures or illustrations and 100 tables.

• Physical Therapy Rehabilitation Science
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• 제5권2호
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• pp.101-105
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• 2016

Objective: The purpose of this study was to measure the change in pain threshold of levator scapular muscle, carniovertebral angle, and head position angle when applying a head-weight device on healthy adult. Design: Cross-sectional study. Methods: This study was conducted with 21 healthy adult male and female who voluntarily agreed to participate in this study after being informed of the purpose and method of this study. After measuring the cervical angle and pain threshold of levator scapular muscle, subject was instructed to walk for 5 minutes on a treadmill at a speed of less than 5 km/h while wearing after wearing head-weight device of 0.5 kg. Then, cervical spine angle and pain threshold of levator scapula muscle were re-measured. Measurement of cervical spine angle was conducted with photo by using the Bluebeam Revu software and the pain pressure thresholds (PPTs) were measured using an electronic algometer over potential trigger points on the body. Results: The results cervical angle showed a significant change, from $49.62^{\circ}$ to $52.10^{\circ}$ (p<0.05). PPT showed a significant change, from 30.71 to 36.89 (p<0.05). Conclusions: These findings suggest that applying head-weight device has a positive influence on increasing cervical angle and reducing pain when applied as a therapeutic intervention method of forward head posture.