• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.72-78
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• 2001

An experimental investigation was conducted to examine the tribological behavior of NAO (non-asbestos organic) type brake linings containing different volume ratios of graphite and antimony trisulfide (Sb$_2$S$_3$). In order to investigate the effect of the solid lubricants on brake performance, three different friction tests (pressure, speed, and temperature sensitive tests) were carried out using a scale dynamometer. The test results showed that the friction characteristics were strongly affected by the type and the amount of solid lubricants in the brake lining. It was found that the brake linings with both solid lubricants were better in friction stability due to the complementary role of the two disparate lubricating properties at various pressure and speed conditions. In particular, the brake lining containing higher concentrations of graphite showed better fade resistance than others during high temperature friction test.

• 대한기계학회논문집A
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• 제26권4호
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• pp.667-676
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• 2002

Many studies on the finite element modeling for bolted joints have proceeded, but the structures with bolted joints are complicated in shape and it is difficult to find out the characteristics according to joint condition. Usually, experimental methods have been used for bolted joint analysis. A reliable and practical finite element modeling technique for structure with bolted joints is very important for engineers in industry. In this study, three kinds of model are presented; a detailed model, a practical model and a simple model. The detailed model is modeled by using 3-D solid element and gap element, and the practical model is modeled by using shell element (a portion of bolt head) and beam element (a portion of bolt body), the simple model is modeled by simplifying practical model without using gap elements. Among these models, the simple model has the least degree of freedom and show the effect of memory reduction of 59%, when compared with the detailed model.

• 영미문화
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• 제18권4호
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• pp.139-162
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• 2018

In "Adventure" Alice Hindman tries to express her repressed sexual instinct with impulsive adventures but becomes a grotesque through her own self-deception and extreme loneliness. She has a passionate relationship with Ned Currie at 16, which defines her identity and molds her entire life. She does believe that Ned may return and stick to his disingenuous word and promises, and holds on to it as the only and absolute truth in her life. Her distortion of reality is in fact based on her self-deception and falsehood she creates. Seized by a strange urge, her second adventure indicates that she wants to feel closer to another grotesque that can understand her loneliness, and that her desire for communication transcends her sexual desire. At the end of the story, she seems to realize that she will die in her bed alone, misunderstood and unloved. But this conclusion shows that, despite the opportunity and potential of another choice, she never makes positive choices and refuses to accept responsibility for her actions. She rather creates an excuse with empty words and shows the limits so as not to get out of her own self-deception. Instead of focusing on Alice's strange behavior and blaming her, Anderson emphasizes the importance of understanding and communication while exploring the sorrow and loneliness of a woman who wants to be loved but is obsessed with self-deception in Winesburg.

• Journal of Information Technology Applications and Management
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• 제25권4호
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• pp.23-39
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• 2018

The purpose of this study was to investigate empirically whether the expected effects of smart work in organizations were different between job types and positions. The development of information technology is demanding innovation of working style within the enterprise. There is a tendency to prefer the face-to-face working style in traditional organizations in the case of some positions or job types. However, many companies are carrying out smart work such as teleworking or telecommuting, flexible working time. But many companies still stick to their existing working methods. There is also the causal relationship between accepting attitudes toward smart work and expectation effects, depending on the position and the job types, even within the same organization. As a result of research, causal relationship analysis showed that the significant factors affecting productivity were teleworking and increasing work efficiency. The national social cost savings were influenced by the improvement of quality of life and flexible working hours. In order to activate communication within the organization, there was a positive effect on the increase of work efficiency. Only flexible working hours between the general manager and subordinates showed a significant difference.

• Journal of the Korean Wood Science and Technology
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• 제50권3호
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• pp.193-217
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• 2022

The Wooden Seated Amitabha Buddha Triad and Altarpiece have not been the subjects of definitive species identification and scientific analysis. In this study, visual investigation, portable X-ray fluorescence (p-XRF), species identification, and lacquer layer observations were carried out to determine the original materials and conservation status. Cracks, exfoliation and discoloration were detected during the visual investigation. The p-XRF data indicated that chrome oxide green, malachite, gold, cadmium red, cinnabar, minium, hematite, lead white, ink stick (Carbon), and copper were used for pigments and the coronet accessory. Tilia spp., Abies spp., and Pinus spp. were identified from both the Buddha Triad and Altarpiece. Finally, lacquer layer analyses of the base layer, lacquer layer, orange pigment layer, and gold leaf layer observed modern synthetic pigments likely used in previous conservation. As the Korean Cultural Heritage Charter and the International Charter for the Conservation and Restoration of Monuments and Sites clearly state that objects of cultural heritage must be conserved using their original materials, future conservation of these objects should utilize the data obtained in this study to employ traditional materials. Furthermore, a deterioration map diagnosis can be applied together with the obtained analysis data to understand the conservation status of and inform an appropriate and authentic conservation treatment for the Buddha Triad and Altarpiece.

• 수산해양기술연구
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• 제36권3호
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• pp.166-174
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• 2000

멸치초망용 챗대의 유압 권양장치를 개발하기 위하여 모형 챗대와 그물을 실물의 1/5크기로 제작하여 챗대를 권양할 때의 장력을 측정하고, 이를 토대로 권양기 3종을 설계 제작하여 그 성능을 시험한 결과를 요약하면 다음과 같다. 1. 챗대를 건양하는데 가장 큰 장력이 작용할 때는 챗대 끝이 수면 하 4m에 있을 때이었고, 이 때 챗대줄에 작용하는 장력은 187.5kgf이었다. 2. 멸치초망 어업에 적합한 권양기의 조건은 어탐중 챗대가 움직이지 않아야 하며, 그 방법으로 감속기나 전자브레이크를 장치하는 것보다 시간 경과에 따른 누수량이 적은 것을 사용하는 것이 바람직하였다. 3. 시험에 사용된 권양기 중 최적의 권양기에 있어서 압력차 $\Delta$P를 130kgf/$\textrm{cm}^2$으로 고정하였을 때, 권양기에 감겨지는 챗대줄의 권양속도는 2m/sec로서 재래식 방법보다 0.48m/sec 빠르게 나타났으며, 양망당 약 1.6톤의 멸치를 어획할 수 있다. 4. 권양기 2대를 설치함으로써 조업인원 2명을 절감할 수 있었다.

• Journal of Oral Medicine and Pain
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• 제36권4호
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• pp.215-224
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• 2011

본 연구의 목적은 과민치아에 904 nm GaAs 다이오드 레이저를 조사하여 치료효과를 연구하여 과민 치아의 치료에 이러한 저수준 레이저 요법을 임상적으로 사용할 수 있는지 가능성을 파악하는 데 있다. 단국대학교 치과대학 부속치과병원 안면 동통 구강내과에 내원한 환자를 대상으로 하였으며, 각 환자는 치경부에 사아질이 노출된 치아가 적어도 좌우로 2개 이상의 짝이 되는 치아를 소유하였다. 본 연구에 사용된 치아는 모두 50 개로써 실험군 25개, 대조군 25 이었다. Tactile test, cold(ice stick) test, electrical pulp test 를 실험전, 실험 1주후, 2주후, 3주후, 4주후 모두 5회 시행하였다. 레이저조사는 첫방문시, 1주후, 2주후, 3주후 등 4회하되 모두 세가지 검사를 마친 후 시행하였다. 전기치수 검사 외 Tactile test와 cold test는 주관적 평가인 visual analogue scale을 사용하였다. 실험 결과, Tactile test에서 VAS 수치는 시간 경과에 따라 유의하게 감소하였으나 실험군과 대조군간에는 유의한 차이가 없었다. 전기치수 검사에서는 실험군의 과민도가 대조군에 비해 유의하게 높았으나 (높은 역치를 의미) 시간 경과시 유의한 변화는 볼 수 없었다. 온도 (cold) 검사에서는 레이저 조사후 실험군과 대조군 간의 차이뿐 만 아니라 시간 경과 시에도 유의하게 감소하였다. 이러한 결과를 보아 904 nm GaAs 레이저는 과민치아의 치료에 비가역적인 방법으로서 효과적으로 사용할 수 있으리라 사료된다.

• 한국전산구조공학회논문집
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• 제23권2호
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• pp.199-208
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• 2010

건물에 설치된 마찰감쇠기는 외력의 크기에 따라 정지와 운동의 상태를 반복하여 외부 입력에너지를 소산시키기 때문에 외력과 응답관계가 비선형이다. 마찰감쇠기가 설치된 단자유도 건물은 마찰감쇠기외에 점성감쇠가 동시에 존재하므로 해석적인 정해를 구하기가 어렵다. 본 연구에서는 첫째, 점성과 마찰감쇠가 있는 단자유도계 건물의 자유진동 정해를 통하여 변위응답과 가속도 응답특성을 분석하였다. 둘째, 자유진동의 경우 응답이 멈출 때까지 소산에너지식을 이용하여 등가점성감쇠비를 구하였다. 셋째, 조화가진 일 때는 수치해석을 통하여 마찰력비 $F_r$에 따른 응답 특성을 알아보았다. 넷째, 조화가진의 경우 에너지 균형식을 바탕으로 등가점성감쇠비를 유도하였다. 등가점성감쇠비는 변위응답비의 영향을 받으므로 응답을 알아야만 구할 수 있다. 건물 응답의 진동수 특성은 협소영역(narrow band)이므로 고유진동수에 의해 지배된다고 가정하여 등가점성감쇠비를 구하였다. 마지막으로, 유도한 자유진동과 조화가진의 등가점성감쇠비를 이용한 등가선형운동방정식의 해를 비선형 수치해석 한 결과와 비교하여 검증하였다.

• Journal of Preventive Medicine and Public Health
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• 제28권1호
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• pp.225-243
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• 1995

Benzidine Industry in Korea has started after Japan has banned its production in early 1970's, and it has been in operation in Korea for over 20 years. However, it is not known yet whether any bladder cancer has developed from benzidine exposure. This study was done to screen benzidine-exposed workers for bladder cancer, and to examine the feasibility of employing screening test at the workplace. All the workplaces that manufacture or use benzidine for more than 20 years in Korea have been covered in this study, and they include 2 benzidine manufacturing factories, 5 benzidine using factories, as well as 2 benzidine free factories as an outside control. In total, 516 workers were screened with urine stick test and urine cytology test for the evidence of hematuria and abnormal urothelial cells. Each worker was also asked about risk factors and symptoms of bladder cancer including past medical history, smoking, medication and occupational history Benzidine in the air was measured by personal and area sampling. Out of 516 screened workers, 84(16.3%) workers showed positive hematuria in urine stick test, and 7(1.4%) workers showed degenerative cells in urine cytology tests. Those workers with abnormal urine test results who have been exposed to benzidine fo more than 10 years were further screened, and, in total, 23 workers were examined with intra-venous pyelography and cystoscopy. None of those screened had any evidence of bladder cancer When workers with only past hematuria history were included in the positive hematuria group, 96(18.5%) had positive hematuria. On the multiple logistic regression analysis, positive hematuria was significantly associated with benzidine exposure, history of other occupations with elevated bladder cancer risk, pyuria and glycosuria. The association got stronger as direct benzidine exposure was accounted through individual task analysis, and as exposure duration was accounted with tenure analysis. For those with benzidine exposure with more than 10 years of tenure, the odds of having positive hematuria was elevated 2.14(95%C.I is 1.08 to 4.25) times more than for those without exposure. Even though bladder cancer was not detected for several limitations including short observation period, majority of studied workers with short latency, healthy worker effect, and low sensitivity of single screening test in a cross-sectional study, the study results suggest that hematuria screening is a feasible and very useful test for bladder cancer screening among benzidine exposed workers.

• 한국도로학회논문집
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• 제14권1호
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• pp.35-43
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• 2012

정부는 교통사고 사상자를 절반으로 줄이기 위하여 생활권 보행자 안전 확보를 위한 안전대책을 선정하여 추진 중에 있다. 주요 추진내용을 살펴보면 중앙선 침범 및 무단횡단 예방을 위해 도심형 중앙분리대 설치기준 마련이 포함되어 있어 기준마련을 위한 연구가 매우 시급한 실정이다. 이에 본 연구에서는 보행자 및 중앙선 침범 교통사고 분석, 도심형 중앙분리대에 대한 형식 및 성능기준, 최소 횡단구성 연구를 통한 설치 기준에 관한 연구를 수행하였다. 그 결과 도시부 차량 불법유턴, 보행자 무단횡단 사고를 줄이고자 시선유도봉을 개조한 도심형 중앙분리대는 차량용 방호울타리의 강한 방호기능을 가질 수 없기 때문에 차량과의 충돌 후 파손되어 부재이탈이 발생하게 되면 2차 사고 등을 유발하게 되어 교통안전에 부(-)의 효과를 가져 올 수 있는 것으로 분석되었다. 이에 주행안전성 측면을 고려해 볼 때 도심형 중앙분리대를 설치할 경우 중앙분리대 폭 1.0m 이상을 확보해야만 시설물 파손이나 차로 이탈을 방지할 수 있는 것으로 분석되었다. 단, 부득이 도로 폭이 좁아 용지확보가 곤란한 경우 0.5m 이상 노면표시만 설치한 경우에 한해 도심형 중앙분리대의 설치를 할 수 있다. 또한 현재 중앙선 위에 시선유도봉이나 도심형 중앙분리대를 설치하는 것은 운전자 실수에 의한 중앙선 침범을 유발할 가능성이 높고 이로 인해 시설물 파손의 가능성이 높아 중앙선 위에는 표지병 이외의 시설물 설치를 금하는 것이 바람직하다.