• Journal of Welding and Joining
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• 제8권3호
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• pp.39-52
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• 1990

The research is to insure the soundness of the stainless steel overlaid weld metal(21/4Cr-IMo steel + SUS 309L) for a pressure vessel application. Detail studies were conducted for the PWHT influence on the micrstructure and intergranular corrosion characteristics of the overlaid weld metal as well as initiation of hydrogen embrittlement crack(or Disbonding) when welded metal are exposed to the hydrogen atmosphere. Hydrogen was experimentally charged to the overlaid weld metal in order to study PWHT effect on the susceptibility of hydrogen embrittlement crack. The results of this research are as follows: 1. At the bond region, austenite grain of the stainless steel side became coarsed and Cr23C6 type carbide was precipitated at the coarsed austenitic grain boundaries. Intergranular Corrosion width(by Straiss test) increased with increasing PWHT temperature and PWHT time.

• 소성∙가공
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• 제19권5호
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• pp.273-276
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• 2010

In this paper, back pressure forging processes of which back pressures are exerted by mechanical forces including spring reaction are simulated by three-dimensional finite element method. The basic three-dimensional approach extended from two-dimensional approach is accounted for. An axisymmetric backward and forward extrusion process having a back pressing die, which is exposed to oscillation of forming load due to variation of reduction ratios with stroke and its related frequent variation of major deforming region, is simulated by both two and three dimensional approaches to justify the presented approach by their comparison. A three-dimensional forging process having a back pressing die attached to the punch by a mechanical spring is simulated and the results are investigated to reveal accuracy of the presented approach.

• Safety and Health at Work
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• 제4권2호
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• pp.84-86
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• 2013

Despite the fact that asbestos is a known carcinogen to humans, it is still used in industrialized countries, especially Asian countries. The global incidence of asbestos-related diseases (ARDs) due to the past use of asbestos, continues to increase, although many countries have adopted a total ban on asbestos use. The implementation of effective strategies to eliminate ARDs is therefore an important challenge in Asia, where asbestos is still mined and consumed. Collaborative efforts and strategies at the local and international levels are vital, in the pursuit toward the elimination of ARDs in this region.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1020-1025
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• 2003

A successful design approach for noise barriers should be multidisciplinary because noise reduction goals influence both acoustical and non-acoustical considerations, such as maintenance, safety, physical construction, cost and visual impact These various barrier design options are closely related with barrier dimensions. In this study, we have proposed an optimal design method of noise barriers using simulated annealing algorithm, providing a barrier having the smallest dimension and achieving the specified noise reduction at a receiver region exposed to the industry and infrastructures, to help a successful barrier design.

• 한국철도학회논문집
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• 제6권1호
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• pp.21-28
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• 2003

Environment-dependent fatigue life of Cu-Cd alloy wires used as messenger wires was investigated. Tensile test results showed the decrease of tensile strength and elongation of messenger wires by 3.7% and 16.8%, respectively, in used specimens when compared to new ones. Messenger wires used at industrial region for 26 yeras showed 35∼50% decrease in fatigue life, which is partly due to the in stress concentrations by formation of corrosion products at the surface. Single wires showed better fatigue properties than stranded wires, especially at low cycle regions with higher stresses. Stranded wires showed shorter fatigue lives than single wires because of friction between wires by surface contact. Service life of messenger wires was dependent upon the environments which they were exposed to. SO$_2$ and humidity deteriorated the fatigue properties by environmental degradation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.561-565
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• 1999

We measured the optical properties in Ag/chalcogenide films with the exposure of 325nm-Held laser In addition we have investigated the Ag doping mechanism as considering the changes of Ag-concentration distribution and optical energy gap ( $E_{op}$ ) with Photon-dose. The "windows" characteristics of Ag thin film occur around the wavelength of 325 nm and the Ag is evaluated to be transparent, without an absorption, in the region. While the $E_{op}$ of S $b_2$ $S_3$ thin film was changed largely by an exposure of HeNe laser(632.8 nm) an exposure of HeCd laser resulted in relatively small variation of $E_{op}$ . Therefore it is thought that photon absorption at the metal layer plays an important role in Ag photodoping.on at the metal layer plays an important role in Ag photodoping.

• 한국BIM학회 논문집
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• 제10권1호
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• pp.23-29
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• 2020

The vacant houses commonly observed in urban aging are considered to be representative signs of urban decline. Vacant houses are themselves vulnerable to security, and in particular, they are exposed to disasters due to poor management, which can accelerate the decline of the area. This study is to classify the area and analyze the causes and characteristics of the occurrence of vacant houses by type based on the data through the survey on the vacant houses in Incheon. This research analyze vacant house data survey so to characterized and categorized types of vacant houses. The criteria of vacant houses analysis are population density, population growth, aging extent. In conclusion there are four types of region in Incheon area according to housing types, hazard classes, building age and building areas. Type A is inner city, type B is mixed, type C is expandable and type D is unsular types.

• 대한전자공학회논문지SP
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• 제47권6호
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• pp.107-116
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• 2010

스미어 현상은 CCD 센서의 전하 전달 과정에 기인한다. 정지 영상에서는 기계적 셔터와 같은 하드웨어적인 구조로 이를 제거하지만, 동영상에서는 수행 시간의 제약 등의 문제로 이러한 방식이 적용될 수 없다. 본 논문에서는 신호처리 관점에서 스미어 현상을 제거하여 정지 영상뿐만 아니라 동영상에도 적용이 가능한 스미어 제거 방식을 제안한다. 제안하는 방식은 CCD 센서의 모서리 부분에 존재하는 화소들의 집단인 광학암흑영역(optical black region)을 이용한다. 광학암흑영역은 실제로 빛의 영향을 받지 않아 상이 맺히지 않지만, 스미어가 발생할 경우 전하 전달에 의하여 스미어 신호가 저장된다. 따라서 제안하는 방식은 스미어 신호를 정확하게 추정하기 위해서 광학암흑영역에 발생한 신호로부터 스미어와 잡음에 의한 영향을 구분하고 잡음은 제거하면서 스미어 신호는 유지하는 과정을 선행하며, 이렇게 처리된 광학암흑영역 신호를 영상 전반에 빼주어 스미어 현상을 제거한다. 또한 스미어 현상에 의해 포화가 발생한 경우는 손실된 원 신호의 정보를 주변의 화소 값으로 대체하여 스미어 현상에 의한 시각적 열화를 개선한다. 실험 결과를 통해 제안하는 방법이 기존 방법에 비해 시각적인 면에서 뛰어난 결과를 보임을 확인할 수 있다.

• 한국산업보건학회지
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• 제25권4호
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• pp.534-541
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• 2015

Objectives: This study was conducted to evaluate the prevalence rate of multiple chemical sensitivity/idiopathic environmental intolerance(MCS/IEI) among workers in the Gumi industrial complex around the region of accidental release of hydrogen fluoride in 2012. Materials: We evaluated MCS/IEI using the Korean version of the Quick Environmental Exposure and Sensitivity Inventory(QEESI). A total of 535 workers at six manufacturing companies in the Gumi industrial complex were investigated using self-administered questionnaires from February to March 2015. After exclusion of incompletely answered questionnaires, 271 were analyzed. Results: The prevalence rate and proved positive rate of MCS/IEI were 5.9%(16 out of 271) and 3.7%(10 out of 271), respectively. The scores of chemical intolerance, other intolerance, symptom severity and life impact were significantly higher(p<0.05) in females than those of males. In terms of masking index scores, males showed significantly higher(p=0.003) than female. The self-reported MCS/IEI prevalence rate, 7.7%, of workers exposed to hydrogen fluoride in 2012 was higher than no-exposure group(5.6%), but not statistically significant(p=0.815). Conclusions: Although the prevalence rate of MCS/IEI symptoms of workers exposed to hydrogen fluoride gas in 2012 was not significantly higher than no-exposure group, it is necessary to conduct follow-up study on the exposure group of hydrogen fluoride.

• 생명과학회지
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• 제18권10호
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• pp.1400-1409
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• 2008

본 연구는 집돼지 사체주위에서 채집되는 곤충의 천이패턴을 이용해서 사체의 사후경과시간을 추정하기 위한, 법의학적 증거모델을 제시하고자 수행되었다. 사체의 주변에서 총 7목28과 48종의 곤충이 채집되었는데, 계절에 따라 많이 나타나는 곤충이 변하여 3월, 5월 및 10월에는 검정파리과가, 7월에는 검정파리과와 반날개과가 같은 비율로, 9월에는 반날개과가 많이 관찰되었다. 검정파리과 곤충은 모든 실험을 통해서 사체에 가장 먼저 도착하는 곤충이며 또한, 부패초기의 지표곤충임이 밝혀졌다. 그러나 부패후기의 지표곤충은 3월을 제외한 나머지 연구기간 중에는 반날개과, 3월에는 집파리과였는데, 3월에는 낮은 온도로 인해서 사체 부패 기간이 오랫동안 지속되었으므로 사체 주위에 모여든 집파리과의 개체수도 증가한 것으로 생각되었다. 이상으로부터 사체의 사후경과시간을 유추하기 위해서는 사체의 부패 정도나 사체 주변에 나타나는 곤충 뿐 아니라, 조사 지역의 기후 조건도 고려해야 할것으로 생각되었다.