• 한국산학기술학회논문지
• /
• 제15권6호
• /
• pp.3416-3422
• /
• 2014

쇼크 업쇼바의 로드는 피스톤부 중심에 위치하여 왕복운동을 담당하는 부분으로 표면의 불량(찍힘)이 있을 경우 감쇠력에 대한 차이로 제품 성능을 제대로 발휘하는데 문제 발생의 요인이 되고 있다. 로드표면은 열처리 상태로 표면 광택으로 인하여 쉽게 불량이 표시되지 않으며, 작업자가 육안으로 로드의 이물질 및 찍힘, 기포 검사를 진행함으로써 눈의 피로도가 높아지고, 작업자 육안에 의존하기 때문에 제품의 검사 품질이 일정하지 않다. 본 연구에서는 제품의 원통 형상을 고려하여 라인스캔카메라를 이용한 머신비전 영상처리 기법으로 0.3mm이상의 표면의 불량을 검출하고, 검사단계에서 발생할 수 있는 표면 불량을 최소화하기 위한 전 공정 자동이송 및 양불 제품의 혼입을 방지하는 자동검사 시스템 개발에 대한 연구를 수행하였다. 표면검사 시스템 개발로 작업자의 육안 검사에 의존하고 있던 쇼크업쇼버 로드의 표면에 대한 정밀 검사시스템 구축으로 품질검사 기준을 확보하고 표준화된 검사로 신뢰도가 향상되었다.

• 한국안전학회지
• /
• 제33권3호
• /
• pp.15-20
• /
• 2018

There have been a number of major fatal fire accidents in Korea recently. The number of fires in 2017 were 44,178, which is not only increasing number of fires but also increasing in casualties. Particularly, the fire at Jecheon Sports Center, which suffered many casualties, is expected to have a huge impact. The cause of the fire has not been determined yet, but heat waves on the ceiling have also been pointed out. As such, the copper heating waves, which are used as a preventive measure against damage of pipes due to freezing of pipes, etc., always have a fire hazard. To determine the possibility of a flame-resistant heated fire, a positive electric cable product was used to artificially ignite and analyze the results. In case of a short circuit, the external covering of the positive electric cable is damaged, but not short circuit unless the heating material surrounding the wire is damaged. Due to the characteristics of heating cable for preventing copper waves, the chances of insulation becoming more severe due to moisture and temperature changes are higher than normal wires. If the internal heating system is carbonized by insulating deterioration without damage to the outer coating, it is likely to cause trekking, to form a winding loop in the heating materials, and to cause short circuit in the heated materials. For the positive temperature line, if the middle is shorted, the current continues to flow to the short circuit unless the breaker disconnects. Consequently, a heated fire that does not cut off the power immediately may leave multiple marks or cuts.

• Journal of Microbiology and Biotechnology
• /
• 제24권12호
• /
• pp.1728-1735
• /
• 2014

Scrub typhus, caused by infection with Orientia tsutsugamushi, is a mite-borne zoonotic disease endemic to the Asian-Pacific region. In Korea, the incidence of this disease has increased with climate changes, and over 10,000 cases of infection were reported in 2013. Although this infection is treatable with antibiotics such as doxycycline and azithromycin, an effective prophylactic vaccine against O. tsutsugamushi would be more desirable for preventing scrub typhus in endemic areas. In this study, we investigated the 56-kDa type-specific antigen (TSA56), which is a major outer membrane protein of O. tsutsugamushi, as a vaccine candidate. Intranasal immunization of recombinant TSA56 (rec56) induced a higher level of TSA56-specific IgG than that induced by intramuscular immunization of tsa56-expressing DNA (p56). Both types of immunization induced a cell-mediated immune response to TSA56, as demonstrated by the splenic cell proliferation assay. Mice immunized with p56, followed by rec56 plus heat-labile enterotoxin B subunit from E. coli, had a stronger protection from a homologous challenge with the O. tsutsugamushi Boryong strain than with other combinations. Our preliminary results suggest that an effective human vaccine for scrub typhus can include either recombinant TSA56 protein or tsa56-expressing DNA, and provide the basis for further studies to optimize vaccine performance using additional antigens or different adjuvants.

• BMB Reports
• /
• 제38권5호
• /
• pp.584-590
• /
• 2005

Glucose 6-phosphate dehydrogenase (EC 1.1.1.49) was purified from Aspergillus aculeatus, a filamentous fungus previously isolated from infected tongue of a patient. The enzyme, apparently homogeneous, had a specific activity of $220\;units\;mg^{-1}$/, a molecular weight of $105,000{\pm}5,000$ Dal by gel filtration and subunit size of $52,000{\pm}1,100$ Dal by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The substrate specificity was extremely strict, with glucose 6-phosphate (G6P) being oxidized by nicotinamide adenine dinucleotide phosphate (NADP) only. At assay pH of 7.5, the enzyme had $K_m$ values of $6\;{\mu}m$ and $75\;{\mu}m$ for NADP and G6P respectively. The $k_{cat}$ was $83\;s^{-1}$. Steady-state kinetics at pH 7.5 produced converging linear Lineweaver-Burk plots as expected for ternary-complex mechanism. The patterns of product and dead-end inhibition suggested that the enzyme can bind NADP and G6P separately to form a binary complex, indicating a random-order mechanism. The enzyme was irreversibly inactivated by heat in a linear fashion, with G6P providing a degree of protection. Phosphoenolpyruvate (PEP), adenosinetriphosphate (ATP), and fructose 6-phosphate (F6P), in decreasing order, are effective inhibitors. Zinc and Cobalt ions were effective inhibitors although cobalt ion was more potent; the two divalent metals were competitive inhibitors with respect to G6P, with $K_i$ values of $6.6\;{\mu}m$ and $4.7\;{\mu}m$ respectively. It is proposed that inhibition by divalent metal ions, at low NADPH /NADP ratio, is another means of controlling pentosephosphate pathway.

• Molecular & Cellular Toxicology
• /
• 제1권2호
• /
• pp.73-77
• /
• 2005

Nickel is the one of potent environmental, the occupational pollutants and the classified human carcinogens. It is a serious hazard to human health, when the metal exposure. To prevent human diseases from the heavy metals, it is seemingly important that understanding of how nickel exerts their toxicity and carcinogenic effect at a molecular and a genomic level. The process of nickel absorption has been demonstrated as phagocytosis, iron channel and diffusion. Uptaked nickel has been suggested to induce carcinogenesis via two pathways, a direct DNA damaging pathway and an indirect DNA damaging pathway. The former was originated from the ability of metal to generate Reactive Oxygen Species (ROS) and the reactive intermediates to interact with DNA directly. Ni-generated ROS or Nickel itself, interacts with DNAs and histones to cause DNA damage and chromosomal abnormality. The latter was originated from an indirect DNA damage via inhibition of DNA repair, or condensation and methylation of DNA. Cells have ability to protect from the genotoxic stresses by changing gene expression. Microarray analysis of the cells treated with nickel or nickel compounds, show the specific altered gene expression profile. For example, HIF-I (Hypoxia-Inducible Factor I) and p53 were well known as transcription factors, which are upregulated in response to stress and activated by both soluble and insoluble nickel compounds. The induction of these important transcription factors exert potent selective pressure and leading to cell transformation. Genes of metallothionein and family of heat shock proteins which have been known to play role in protection and damage control, were also induced by nickel treatment. These gene expressions may give us a clue to understand of the carcinogenesis mechanism of nickel. Further discussions on molecular and genomic, are need in order to understand the specific mechanism of nickel toxicity and carcinogenicity.

• 한국화재소방학회논문지
• /
• 제25권5호
• /
• pp.1-7
• /
• 2011

본 연구에서는 한옥의 주요 부재에 대한 난연기술 개발 및 성능향상을 위한 기초단계로 미국, 일본, 유럽 및 국내의 건축물 마감재의 난연성능 관련 법규 및 시험기준 등을 비교 분석하여 각 부재의 난연성능 평가기준을 제시하고자 하였다. 미국의 경우 최근 통합되어 사용 중인 IBC(International Building Code) 및 NFPA(National Fire Protection Association) Code가 적용되고 있으며, 평가항목으로는 바닥재에 대해서는 임계열유속을, 천장 및 벽체에 대해서는 화염확산지수 및 연기발생량을 적용하고 있다. 유럽의 경우 통합된 Euroclass가 적용되고 있는데 바닥재와 비바닥재를 구분하여 난연성능 등급별로 불연성시험, 화염 전파성시험, 소규모실물화재시험, 발열량시험 등을 평가항목으로 두고 있다. 일본의 경우는 우리나라의 체계와 유사하였는데, 이들 각국의 기준을 비교분석하여 목조물인 한옥 부재에 적용할 수 있는 정량적인 난연성능 평가방법에 대해 고찰해 보았다.

• 한국추진공학회지
• /
• 제15권2호
• /
• pp.68-73
• /
• 2011

소형위성발사체 (KSLV-I)의 발사 준비에는 다양한 규격의 질소 가스 및 초저온 액체 질소가 소요된다. 발사대 질소 공급 시스템은 고압의 질소 가스 생성, 추진제 충전 후 발사 대기 중인 발사체의 보호를 위한 공간 퍼지용 질소 가스 생성, 연료 및 산화제의 냉각을 위한 액체 질소 공급 기능을 수행하기 위하여 개발되었다. 대기 환경 조건에 따라 열전달 특성이 민감하게 변화하는 대기식 기화기의 운용 불안정성을 제거하기 위해 기화기의 병렬 설치 및 교대 운용 절차를 도입하였다. 이를 통하여 기후 조건에 상관없이 항시적으로 운용이 가능한 시스템을 개발하였으며, 소형 위성 발사체의 비행 시험을 위한 발사대 운용을 성공적으로 수행하였다.

• 한국추진공학회지
• /
• 제14권5호
• /
• pp.32-44
• /
• 2010

고체 추진기관 노즐의 2차원 열반응 및 삭마 해석 코드를 활용하여 노즐 부품의 숯 및 삭마현상을 연구하였다. Arrhenius 식을 이용한 내부 열분해 모델 상수는 TGA(열중량분석기) 실험으로 얻었다. 탄소와 $H_2O$, $CO_2$의 산화반응에 의한 화학적 삭마는 Zvyagin이 제안한 삭마모델 과 반응속도 상수를 이용하여 해석을 수행하였다. 삭마에 의한 경계조건 및 격자 이동은 상용해석 프로그램인 MSC-Marc-ATAS에서 적용되는 Rezoning-remeshing 기법을 사용하였다. 해석된 숯 및 삭마 두께는 연소시험 결과 값과 최대 20% 오차를 보였다. 향후 열방호 시스템의 성능을 모사하기 위하여 내부 온도 및 열유속을 실시간 측정하면 3차원 FEM 통합 열구조 해석에 적용될 것으로 기대된다.

• 한국태양에너지학회 논문집
• /
• 제34권2호
• /
• pp.73-81
• /
• 2014

Ocean thermal energy conversion(OTEC) is a power generation method that utilizes temperature difference between the warm surface seawater and cold deep sea water of ocean. As potential sources of clean-energy supply, Ocean thermal energy conversion(OTEC) power plants' viability has been investigated. Therefore, this paper evaluated the thermodynamic performance of solar-OTEC convergence system for the production with electric power and desalinated water. The comparison analysis of solar-OTEC convergence system performance was carried out as the fluid temperature, saturated temperature difference and pressure of flash evaporator under equivalent conditions. As a results, maximum system efficiency, electric power and fresh water output show at 40, 10, 2.5 kPa of the flash evaporator pressure, respectively. And their respective enhancement ratios were approximately 6.1, 18, 8.6 times higher than that of the base open OTEC system. Also, performance of solar-OTEC system is the highest in the flash evaporator pressure of 10 kPa.

• 한국태양에너지학회 논문집
• /
• 제36권5호
• /
• pp.73-89
• /
• 2016

To assure maximum economic benefits and the energy performance of solar water heating systems, the proper sizing of components and operating conditions need to be optimized. In recent years, a number of studies to design optimally solar water heating systems have been tried. This paper presents a design method for optimizing the various capacity-related and installation-related design variables based on life cycle cost using a genetic algorithm. The design variables considered in this study included the types and numbers of solar collector and auxiliary heaters; the types of storage tanks and heat exchangers; the solar collector slope; mass flow rates of the fluid on the hot and cold sides. The suggested method was applied for optimizing a solar water heating system for an elementary school in Seoul, South Korea. In addition, the effectiveness of the proposed optimization method was assessed by analyzing the obtained optimal solutions of six case studies, each of which was simulated with different solar fractions. It is observed that a trade-off between the equipment cost and the energy cost results in an optimal design that yields the lowest life cycle cost. Therefore, it could be helpful to apply the optimal solar water heating system by comparing the various design solutions obtained by using the optimization method instead of the engineer's experience and intuition.