• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.115-121
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• 2001

The wear test has been performed to evaluate the wear mechanism of steam generator (SG) tube materials against ferritic stainless steel in water environment. The wear rates of SG tube materials depend on the change of mechanical properties between contact surfaces during wear test. From the subsurface hardness test, Inconel 690 is more work-hardened than Inconel 600 even though these materials have similar hardness values before the wear test. Main cause is due to the difference of stacking fault energy with the chromium content. In water environment, wear mechanism is closely related with the continuous formation and fracture of deformation layers at the contact surfaces.

• Tribology and Lubricants
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• 제18권4호
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• pp.255-259
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• 2002

The tribological properties of eight different liquid crystals were investigated in a concentrated point contact device and a ball-on-flat contact. For comparison, the same tests were also performed with commercial greases and the corresponding base oils. Under the fully flooded conditions studied, liquid crystals in a concentrated point contact showed lower friction than commercial greases and greater film thickness dependence on rolling speed than grease base oils or greases. Test results also showed that the film thickness and friction were little influenced by the composition of the examined liquid crystals.

• Journal of Preventive Medicine and Public Health
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• 제55권5호
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• pp.485-491
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• 2022

Objectives: Tuberculosis (TB) is a major public health concern worldwide. Social contact patterns can affect the epidemiology and risk of airborne diseases such as TB. This study was designed to investigate the social contact patterns associated with TB. Methods: In this case-control study, groups of participants with and without TB were matched by age and sex. Participants reported the nature, location, frequency, and average duration of social contacts over 1 month. The duration and number of social and spatial contacts were compared between groups using the chi-square test and the t-test. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to quantify the relationship between social contact time and TB status. Data were analyzed using Stata version 11 statistical software. A p-value of <0.05 was considered to indicate statistical significance. Results: In this study, 80 patients with TB and 172 control participants were included, and a total of 3545 social contacts were registered. Social contact with family members (OR, 1.72; 95% CI, 1.10 to 2.40), contact with a person with TB (OR, 1.53; 95% CI, 1.16 to 2.01), and contact at the participant's home (OR, 1.42; 95% CI, 1.19 to 1.82) were significantly associated with TB status. Conclusions: The duration of long-term social contact, rather than the number of contacts, may be the main contact-related factor associated with TB transmission in this population. The focus of contact-tracing efforts should be on finding and treating both family members and long-term contacts in non-household settings.

• 임산에너지
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• 제21권2호
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• pp.34-42
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• 2002

천연물계의 유지를 목재에 처리하여 발수성능을 평가하였다. 시험에 사용한 유지는 아마인유, 피마자유, 올리브유, 콩기름, 들기름, 해바라기 씨 기름이다. 발수성 평가는 흡습성, 흡수성 시험과 접촉각 시험으로 하였다. 발수 처리한 목재를 빛과 수분에 의해 촉진열화 시킨 후에 열화정도를 색차계로 측정하였다. 촉진열화된 처리목재의 발수성능을 흡수성시험과 접촉각 시험을 통하여 비교 측정 하였다. 흡습성 시험결과, 흡습 초기에는 무처리에비하여 흡습량이 적으나 흡습처리 시간이 증가할수록 무처리의 흡습량에 가까워져 48시간 흡습처리 후에는 흡습비의 큰 차이는 없었다. 접촉각 시험의 결과, 처리재와 무처리재간의 결과가 큰 차이를 나타내었다. 유지의 농도와 종류에 따른 접촉각 변화는 흡습성 시험과 같이 큰 차이는 나타나지 않았다. 천연유지의 발수성능으로는 기상열화에 대한 안정성이 낮았다. 천연오일 단독처리만으로는 광열화에 대한 안정성을 기대하기 어려웠다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1589-1590
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• 2013

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.281-285
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• 2002

A new method of dynamic contact force measurement between a pantograph and a contact wire is proposed in this paper The method does not require design modification of an original pantograph in order to install sensors such as load cells. Contact forces can be expressed as the sum of vertical shear forces at the support points and inertial forces. Using specially-designed strain gage rosettes. vertical shear forces at the supported points can be measured without noise mixing and thermal effects. In order to obtain contact forces from shear forces, 3 inertial force compansation methods are proposed and compared in this paper. By validation process, the new proposed measurement method is verified to be applicable to the on-line current collection test.

• Journal of the Korean Wood Science and Technology
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• 제39권5호
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• pp.437-443
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• 2011

In Korea, there has been a traditional post and beam wood construction with large roof load. Because a large friction is generated in wooden joint or members, it is important to evaluate the friction between wood members according to wood direction. Because most of studies have been concerned with friction between wood and steel, excluding effect of real area of contact, there are a few studies on the friction between wood members. The object of this study was to evaluate friction or coefficient of friction according to normal force and real area of contact of wood. With Japanese larch (Larix kaempferi) test specimens, five steps of normal force and combinations of test were prepared. Results indicated that normal force had almost no affection on the friction, however there was difference about friction or coefficient of friction according to real contact conditions of wood grain and contact area.

• 한국직업건강간호학회지
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• 제19권1호
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• pp.14-27
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• 2010

Purpose: The purpose of this study was to identify health promoting behaviors and health problems in contact center consultants, and to provide basic data in order to develop health promoting interventions for these people. The subjects were 680 consultants randomly selected from 6 contact centers out of 31 in D city. The data were collected from March 20, to March 28, 2008. Methods: The tools for this study were HPLP II developed by Walker et al. (1995) that was modified and translated by Park (2005) and modified CMI for contact center consultants based on CMI developed by Bordman (1994). The data were analyzed by descriptive statistics, t test, ANOVA, and Scheffe test with the SPSS WIN 14.0 program. Results and Conclusion: The contact center consultants' health promoting behavior was in a low level and they had certain health problems related to their job such as eye, ear and throat. In consideration of contact center consultants' job characteristics, health education should be provided with the development of systematic health programs.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권4호
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• pp.165-172
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• 2003

Low voltage circuit breakers are widely used in power distribution systems to interrupt fault current rapidly and to assure the reliability of the power supply. This paper is focused on understanding the interrupting capability, more specifically of the contacts and the arc runner, based on the shape of the contact system in the current molded case circuit breaker (hereafter MCCB). Moreover, in order to improve the interrupting capability of the circuit breaker, the estimation and analysis of the interrupting capability, based on the 3-D magnetic flux analysis, were developed. Furthermore, this paper also presents results of the estimation and analysis of the interrupting capability when applied to different model breakers. In addition, this paper analyzes the efficiency of the interrupting tests by forming false current paths consisting of a three-division cascade arc runner in the contact system. With regards to the interrupting test, there is a need to assure that the optimum design required to analyze the electromagnetic forces of the contact system generated by the current and flux density be present. Based on the results of this study, this paper presents both computational analysis and test results for the newly developed MCCB 460V/225A/50㎄ contact system.

• 한국안광학회지
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• 제12권4호
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• pp.55-69
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• 2007

본 연구는 ez NANOsence II RGP 콘택트렌즈를 사용하여 굴절이상 눈의 피검자에 대한 시력과 각막에 미치는 임상적 검증을 하였다. 피검자는 성인 121명(남성 29인, 여성 92명; 연령은 17세와 43세 사이, 평균 22.86세)을 대상으로 실시하였다. 피검자는 콘택트렌즈 착용 전의 증상을 포함하는 문진을 실시하였고, 또한 콘택트렌즈 착용전후의 눈에 대한 자각과 타각증상 변화도 검진하였다. 시력측정은 콘택트렌즈를 착용하여 원거리에서 실시하였고, 굴절검사는 타각적 방법(Topcon KR-8100, Japan)으로 나안 상태에서 실시하였다. 입체시 검사는 Titmus fly(Stereo Optical Co., U.S.A)와 TNO(Tech, The Netherlands)로서 콘택트렌즈 착용 후 근거리에서 시행하였고, 대비감도 진단은 콘택트렌즈 착용 후 대비감도 챠드(pelli-Robertson, USA)로 1m 거리에서 실시하였다. 각막 지형도검사는 콘택트렌즈 착용 후 나안상태에서 ORB scan(Bausch Lomb, U.S.A.)을 사용하였다. 콘택트렌즈의 표면미세구조는 SEM(JSM-5800, Japan)을 이용해서 관찰하였고, 콘택트렌즈의 화학 성분은 EDS 프로그램을 사용해서 분석하였다. 연구 결과는 다음과 같다. 1. 렌즈의 착용 기간이 길수록 피검자는 대게 개선된 시각기능을 획득했다. 2. 렌즈 착용에 따른 눈의 부작용은 거의 없었다. 3. 피검자의 렌즈 사용은 잘하고 있다. 4. 렌즈 착용기간이 길수록 각막의 굴절 값은 약간 감소하고, 곡률반경은 약간 증가하며, 각막난시는 감소(P<0.01)하고, 각막의 중앙부 두께도 감소하였다. 5. 렌즈 사용 기간이 길수록, 입체시와 대비감도는 더욱 정상 값을 가졌다. 6. 각막지형도 분석에서 대부분 피검자들은 착용기간의 차이에도 비슷한 형태를 나타내었다. 7. 새로운 렌즈와 사용한 콘택트렌즈의 표면미세구조는 미세 형태에서 비슷한 상태이다. 8. 새로운 렌즈와 사용된 콘택트렌즈의 화학적 구성 성분은 거의 같았다. 결론적으로 본 연구는 새로운 것과 사용된 콘택트렌즈의 표면 미세구조와 화학적 구성성분이 유사함을 확인하였다. 또한 렌즈의 장기 착용에도 피검자의 시기능은 개선되고, 눈의 부작용은 적게 나타났으며, 각막난시 값은 감소되었다. 본 검사는 콘택트렌즈 착용자의 시각기능은 콘택트렌즈의 성분과 미세구조가 시각 기능에 관련이 있다고 여겨진다. 본 연구에서 저자들은 ez NANOsence II RGP 콘택트렌즈는 굴절 이상 눈의 교정시력에 좋은 효과가 있다고 추측된다.