• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.173-174
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• 2014

In this research, the effect of the amount of retarder and the washing timing on the quality of aggregate-exposed concrete produced by water-jet washing method is evaluated as a series of test to develop the aggregate-exposed concrete as a concrete finishing method. As a result, the amount of losing aggregate and surface mortar was increased as the dosage of retarder was increased because of the hydration retarding effect of the retarder. Furthermore, as the washing timing was extended, the mortar on the surface of the concrete was not blown by water jet with 8 to 24 ml of retarder because of hydration of cement, hence the surface quality was poor. Therefore, washing timing of one day after concrete placement showed 90 % of aggregate exposed rate and 24 ml of retarder showed the most favorable result of aggregate exposure.

• 한국안전학회지
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• 제26권5호
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• pp.41-45
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• 2011

The fire event occurred in fire proof zone often causes serious electrical problems such as shorts, ground faults, or open circuits in nuclear power plants. These would be directed to the loss of safe shutdown capabilities performed by safety related systems and equipments The fire event can treat the basic design principle that safety systems should keep their functions with redundancy and independency. In case of a cable fire, operators can not perform their mission properly and can misjudge the situation because of spurious operation, wrong indication or instrument. These would deteriorate the plant capabilities of safety shutdown and make disastrous conditions. In this paper, the cables of the representative nuclear power plant in korea is selected and the cable functional failure temperature by exposed fire using Cable Response to Live Fire(CAROLFIRE) is studied. It is expected that the results are very useful to know the cable failure temperature by exposed fire. We confirmed the safety and integrity of the cable by exposed fire and those results will use the based data of cable exposed fire characteristics.

• Journal of Preventive Medicine and Public Health
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• 제26권2호
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• pp.210-221
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• 1993

In order to evaluate the confounding factors of neurobehavioral tests and the neurobehavioral effects in the workers exposed to organic solvents, NCTB was carried out on 100 workers. 46 workers had never been exposed to neurotoxic substances, and the others were being exposed to the solvents, mainly toluene. Simple reaction time, digit symbol, Santa Ana dexterity test and persuit aiming were different with age in non exposure group. Simple reaction time was carried out well in males, and digit symbol and persuit aiming were in females. There was no difference at educational level when the subject was educated over 12 years. Santa Ana dexterity and Benton visual test differed according to exposure level to toluene, however simple reaction time didn't. The acute neurotoxic effect was not excluded in this study. But, NCTB could be used to evaluate and prevent neurobehavioral changes in workers exposed to neurotoxic solvents in Korea.

• Animal cells and systems
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• 제7권1호
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• pp.29-33
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• 2003

To understand the adaptational strategy of Korean chipmunks (Tamias sibiricus) to cold temperature, blood and serum properties, and thyroid gland activity of cold-exposed chipmunks were examined. The number of erythrocytes and hemoglobin concentration increased, but platelets decreased in cold-exposed chipmunks compared with warm chipmunks. Serum total protein levels increased at early phase of cold-exposure, and decreased thereafter. Plasma glucose levels showed a transitory increase in cold temperature. Although there was significant decrease in serum total thyroxine level in cold-exposed chipmunks, serum total triiodothyronine level changed little. Histological analysis of thyroid glands demonstrated decreased thyroid activity, suggesting that differences in the blood and serum properties between the warm and cold-exposed chipmunks may be due to the different metabolic strategy associated with cold temperature.

• 환경생물
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• 제36권4호
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• pp.456-462
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• 2018

The purpose of this study was to assess cross-generational effects of bisphenol A exposure in benthic copepods, Tigriopus west. Nauplii (<24 hours old) were exposed to graded concentrations of bisphenol A, and toxicity end-points such as survival, development, sex ratio, and fecundity were measured. $F_1$ generations were grown under innoxious conditions, and similarly assessed. Significant differences were observed in development of nauplii and copepodites, between exposed and non-exposed copepods; however, there were no differences in survival of nauplii or copepodites, sex ratio, or brooding rate in parental generation. In contrast, in the $F_1$ generation, there were significant differences between the control group and exposed group in survival and development of nauplii. Length, width, and biomass of parental and $F_1$ generations were reduced in the exposed group compared to the control group. In addition, some deformities, such as swelling of the prosome, abnormally shaped egg sac, and dwarfism were observed after exposure to bisphenol A. So, our study demonstrates that a cross-generation toxicity test and monitoring of morphological deformities in harpacticoid copepods, can be useful for development of potential bioindicators for environmental monitoring, and assessment of chemical impact.

• 대한건축학회논문집:구조계
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• 제34권12호
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• pp.11-20
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• 2018

The purpose of this study is to investigate the seismic performance of exposed column-base plate strong-axis connections for small-sized steel buildings. Even though the seismic design for small-sized buildings became mandatory since Dec.2017, the arbitrary connection details in steel structure have been applied at the construction site, which is considered to be very insufficient to secure structural safety and stability considering the increased seismic risk. Therefore, a series of experimental test programs had been carried out to develop enhanced connection details in order to ensue the adequate seismic safety of small buildings. The hysteretic behavior of the exposed column-base plate connections commonly used in Korea seem to be very pure poor due to the "Rocking" phenomena between anchor plate and concrete by the residual plastic deformation of anchor bolts. A series of hysteretic tests were conducted to find the solution to overcome the "Rocking" phenomena of the exposed column-base plate connections, finally the stable seismic behavior was obtained by uisng at least 8 anchor bolts with good bonding strength to the protptype specimen.

• Journal of Preventive Medicine and Public Health
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• 제26권2호
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• pp.251-267
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• 1993

연폭로의 정도와 자각증상과의 관계를 알아보기 위하여 435명의 연폭로 남자 근로자와 212명의 일반 사무직 남자 근로자를 대상으로 연폭로 지표가 되는 혈중 연, 혈중 Zinc Protoporphyrin(ZPP), 요중 Delta-aminolevulinic acid(DALA), 혈색소, 혈구 용적 측정을 위한 혈액 시료 및 소변 시료를 채취하여 분석하였고, 연관련 자각증상 조사는 14개의 증상 조사 항목을(표 3 및 별첨 1) 피검자가 응답 하도록하여 상담 의사의 면접을 통한 확인을 거쳐 수집 하였다. 수집된 각 항목은 인체 조직계 증상군별로 1) 위장관계 증상 2) 신경과 근육 및 관절계 증상 3) 일반 체질적 증상 4) 정신과적 증상으로 구분하여 연폭로 지표 수준과 연폭로 작업 여부에 따른 자각증상 호소율을 비교 조사하여 얻은 결론은 다음과 같다. 1. 연폭로군에서 대조군보다 유의하게 높은 자각증상 호소율을 보인 증상군은 신경과 근육 및 관절계 증상으로 "손이나 발이 저리거나 쥐가 잘난다", "관절이 아프거나 쑤신다", "손가락, 손, 발 등에 힘이 없다", "근육통을 느낀다" 순 이었다. 2. 연폭로군과 대조군의 자각증상 호소율에 가장 큰 차이를 보인 증상 항목은 "손이나 발이 저리거나 쥐가 잘 난다"였으며, 전체 조사 대상에서 가장 높은 증상 호소율을 보인 증상 항목은 일반 체질적 자각 증상군의 "전보다 피곤감을 느낀다"였다. 3. 전체 조사 대상의 혈중 연과 혈중 ZPP 수준에 따른 연폭로량의 증가와 자각증상 호소율의 증가를 보인 증상 항목은 신경과 근육 및 관절계 증상군의 "손이나 발이 저리거나 쥐가 잘난다", "관절이 아프거나 쑤신다", "손가락. 손 발 등에 힘이 없다", "근육통을 느낀다"와 위장관계 증상군의 "아랫배가 아파서 고생한 적이 있다"였다. 4 연폭로군에서 혈중 연과 혈중 ZPP 수준에 따른 연폭로량의 증가와 자각증상 호소율의 증가를 보인 증상 항목은 신경과 근육 및 관절계 증상으로 혈중 연의 증가에 따라 증상 호소율이 증가하였다. 5. 연폭로군에서 39세 이하 와 40세 이상 연령군으로 나누어 비교시 39세 이하 군의 증상 호소율이 40세 이상 군보다 높게 나왔으며. 신경과 근육 및 관절계 증상이 39세이하 군에서 혈중 연의 증가와 함께, 40세 이상 군에서 혈중 ZPP의 증가와 함께 자각증상 호소율의 증가를 나타냈다. 6. 연폭로 지표에 따른 폭로수준과 증상 호소율과의 관계를 알아보기 위하여 대조군에 대한 폭로군, 연폭로군의 저농도 폭로군에 대한 고농도 폭로군의 교차비를 산출한 결과 신경과 근육 및 관절계 증상군의 "손이나 발이 저리거나 쥐가 잘난다", "관절이 아프거나 쑤신다", "손가락, 손, 발 등에 힘이 없다", "근육통을 느낀다"와 위장관계 증상군의 "아랫배가 아파서 고생한 적이 있다"가 연폭로량의 증가에 따른 교차비의 증가를 보여 양-반응의 관계를 추정할 수 있었다.

• Kyungpook Mathematical Journal
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• 제57권2호
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• pp.223-232
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• 2017

We classify the extreme and exposed symmetric bilinear forms of the unit ball of the space of symmetric bilinear forms on ${\mathbb{R}}^2$ with hexagonal norms. We also show that every extreme symmetric bilinear forms of the unit ball of the space of symmetric bilinear forms on ${\mathbb{R}}^2$ with hexagonal norms is exposed.

• 약학회지
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• 제37권5호
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• pp.458-462
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• 1993

Blood toluene concentrations of thirty nine Korean toluene-exposed workers in shoes making factory were checked by headspace-gas chromatographic analysis. Air toluene concentrations in each worker's working region also checked by personal sampler during workshift and analyzed by gas chromatography. The range of blood toluene concentration was 0.15-0.84mg/L. The range of toluene concentration of each worker's working area was 8.46-189.9ppm. The correlation between blood and air concentration of toluene was 0.824.

• 한국환경보건학회지
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• 제18권2호
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• pp.117-124
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• 1992

Pretreatment with low concentration of Bleomycin and Cadmium rendered Chinese Hamster Ovary Cells more resistant to the induction of chromosome aberration by subsequent high concentration of same agent, however Mitomycin C did not function in that way. The cells pre-exposed to low dose of Cadmitim did not show cross-resistance to challenge dose of Mitomycin C for the induction of chromosome aberration, but cells pre-exposed to Bleomycin showed cross resistance. And the cells pre-exposed to low dose of Mitomycin C showed cross resistance to challenge of Bleomycin, but Cadmium did not.