會計決定危險과 共通要因 敏感度와의 相關關係에 관한 實證硏究

박기정 釜山大學校 商科大學 1986 釜山商大論集 Vol.52 No.-

A Study on Live Load Deflection Criteria of Long-Span Steel Bridges

박기정,김도영,황의승 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.6

Under-clearance of bridges is one of the major considerations when planning and designing bridges. Especially for seacrossing bridges, under-clearance is more important for safe passage of ships. Long span cable bridges with steel orthotropic deck usually show relatively large defl ections and excessive defl ections may be not only disadvantageous to the clearance plan, but also a problem in bridge serviceability. The clearance of sea-crossing bridge is designed with air draft from the waterline to top of mast, ship’s trim, psychological free space, sea level, height of wave and bridge defl ection by live loads. At design stage, bridge engineers need a live load defl ection limit to ensure adequate clearance. The limitation of live load defl ection is also considered for ensuring the serviceability of vibration of bridges. For vibrational serviceability, the live load defl ection limit is expressed as a ratio to the span or the formula by natural frequency. On the other hand, some standards specify vibration serviceability limit by peak or root-mean-square (RMS) acceleration. The purpose of this study is to propose new defl ection limit criteria for long span steel cable bridges based on analysis and long-term measurement data. Structural analysis was performed on two steel suspension and three steel cable-stayed bridges with more than 200 m of main span under design live load model of DL24 and new live load model KL510 in limit state design code. Also, the defl ection limit criterion was evaluated by probabilistic method using the defl ection data measured for 1 year. The results of this study are expected to be useful data for bridge engineers designing long span steel cable bridges.

공정가치회계에 관한 연구

박기정 경남대학교 산업경영연구소 1999 지역산업연구 Vol.21 No.2

개방 수조형 연구용 원자로의 일차냉각재 누설감지를 위한 설계요건 검토

박기정,서경우 한국에너지학회 2023 한국에너지공학회 학술발표회 Vol.2023 No.4

Effects of Molybdenum on HIC Susceptibility in Normalized Pressure Vessel Steels for Sour Service Applications

박기정,조대현,박민호,양철웅 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.7

This paper discusses a molybdenum-added alloy design for normalized pressure vessel steels, to reduce hydrogen induced cracking (HIC) and inhibit crack propagation. The change in microstructure produced by the modified alloy composition was analyzed to determine its effect on HIC characteristics. The microstructural change was observed by optical microscopy, hardness tests, scanning electron microscopy, and electron backscattered diffraction. The crack length ratio and crack thickness ratio were evaluated using the NACE TM 0284 standard, and ultrasonic testing was used for HIC analysis. The formation of polygonal ferrite and pearlite during the processing of the alloy creates localized areas of high stress concentration at the polygonal ferrite/pearlite interface, due to the expansion/contraction of various structures during the transformation. This results in the generation of potential hydrogen-trapping sites, subsequent HIC, and crack propagation. The addition of molybdenum leads to a decrease in the volume fraction of the pearlite structure in the steel in favor of a more beneficial bainitic ferrite microstructure, which is generated during the normalizing process. This bainitic transformation creates a more favorable expansion/contraction compatibility and reduces/breaks up the ferrite/pearlite banding. The combination of these two characteristics can result in an overall lower stress-intensity state, which can minimize hydrogen-trapping and crack propagation. This study demonstrates that the resistance of normalized pressure vessel steels to HIC can be significantly improved by incorporating molybdenum in the alloy design.

소규모 빗물처리시설 개발 및 현장 적용성 평가 연구

박기정,박민승,김환석,임윤수,김성표 한국습지학회 2016 한국습지학회지 Vol.18 No.1

도시화에 따른 불투수면 증가로 인한 자연적 물순환 시스템 왜곡 현상과 더불어 불투수면에 축적된 다양한 오염물질은강우 시 유역 및 하천으로 유입되어 다양한 오염을 일으킨다. 특히 대부분의 강우가 여름철에 집중되는 국내 계절적특성은 집중호우에 따른 비점오염물질의 수계 과대 유입에 대한 우려를 높이고 있어, 이를 효과적으로 처리하고 재이용하기 위한 다양한 형태의 빗물처리 및 재이용 시설에 대한 연구가 필요하다. 이를 위해 본 연구에서는 강우시 지붕유출수의 오염특성을 파악하고, 강우 초기 고농도 빗물 유출수를 효과적으로 처리하기 위한 소규모의 빗물정원 포함형태의 빗물처리시설을 구성하였으며, 처리시설에 포함된 빗물정원에서의 오염물질 처리 효율을 높이기 위해 실험실규모의 인공강우를 이용한 다양한 여재 구성 오염물질(TN, TP, CODcr) 제거율 실험을 실시하였다. 이를 통해 제거효율이 가장 높은 피트머스(Peatmoss)와 자갈, 모래를 구성된 빗물정원을 시범유역에 설치하여 오염물질 제거효율을 측정하였다. 2015년 6월 ∼ 7월까지 4회의 실제 강우에 대한 강우사상별 시간별, 강우사상별, 농도별 오염물질 제거율을분석 한 결과 강우강도가 높거나 강우량이 커질수록 고농도의 오염물질이 빗물처리시설 내 빗물정원으로 유입되었으며, 분석 결과 오염물질의 제거율은 저농도 일 때 보다 고농도 일 때 더 높은 것으로 나타났다. 대규모의 빗물처리시설을 설치하기 어려운 도심지에서, 위와 같은 소규모 시설을 효과적으로 활용 한다면, 도시 유역에서 강우시 발생하는초기세척효과에 의한 비점오염 형태의 오염물질 유입을 차단해 오염물질 부하를 저감하는데 효과적으로 활용 될 수 있을 것으로 판단되며, 나아가 도서 지역내 용수공급을 위한 소규모 재이용 시설로도 활용 가치가 있을 것으로 판단된다. The increase of impervious area in cities caused the unbalanced water cycle system and the accumulated various contaminants, which make troubles as introducing into watershed. In Korea, most of rainfall in a year precipitate in a summer season. This indicate that non-point source pollution control should be more important in summer and careful rainfall reuse strategy is necessary. Accordingly, the aim of this study is to monitor the characteristics of rainfall contaminants harvested in roofs and to develop the rainfall treatment system which are designed to fit well in a typical domestic household including rain garden. The rain garden consists of peatmoss, gravel and san to specially treat the initial rainfall contaminants. For this purpose, lab scale experiments with synthetic rainfall had been conducted to optimize the removal efficiency of TN, TP and CODcr. After lab scale experiments, field scale rainfall treatment system installed as a pilot scale in a field. This system has been monitored during June to July in 2015 in four time rainfall events as investigating the function of time, rainfall, and pollutant concentrations. As results, high loading of pollutants were introduced to the rainfall treatment system and its removal efficiency is increased as increase of pollutant concentrations. Since it is common that the mega-size of rainfall treatment system is not attractive in urban area, small scale rainfall treatment system is promising to treat the non-point source contaminants from cities. In addition, this small scale rainfall treatment system could have a potential to water resue system in islands, which usually suffer the shortage of water.

miRTar Hunter: A Prediction System for Identifying Human microRNA Target Sites

박기정,김기봉 한국분자세포생물학회 2013 Molecules and cells Vol.35 No.3

MicroRNAs (miRNAs) are important regulators of gene expression and play crucial roles in many biological pro-cesses including apoptosis, differentiation, development, and tumorigenesis. Recent estimates suggest that more than 50% of human protein coding genes may be regulated by miRNAs and that each miRNA may bind to 300-400 target genes. Approximately 1,000 human miRNAs have been identified so far with each having up to hundreds of unique target mRNAs. However, the targets for a majority of these miRNAs have not been identified due to the lack of large-scale experimental detection techniques. Experimental detection of miRNA target sites is a costly and time-consuming process, even though identification of miRNA targets is critical to unraveling their functions in various biological processes. To identify miRNA targets, we developed miRTar Hunter, a novel computational approach for predicting target sites regardless of the presence or absence of a seed match or evolutionary sequence conservation. Our approach is based on a dynamic programming algorithm that incorporates more se-quence-specific features and reflects the properties of various types of target sites that determine diverse as-pects of complementarities between miRNAs and their targets. We evaluated the performance of our algorithm on 532 known human miRNA:target pairs and 59 experimentally-verified negative miRNA:target pairs, and also compared our method with three popular programs for 481 miRNA:target pairs. miRTar Hunter outperformed three popular existing algorithms in terms of recall and precision, indicating that our unique scheme to quantify the determinants of complementary sites is effective at detecting miRNA targets. miRTar Hunter is now available at http://203.230.194.162/~kbkim.

상이한 수소이온농도에서 성장하는 Methylobacterium extorquens AM1의 메탄올 이용 관련효소와 Cytochrome c 및 폴리아민

박기정,이순희,김영민 한국미생물학회 1992 미생물학회지 Vol.30 No.6

Methylobacterium extorquens AM1 이 pH 5.5 와 7.0 에서 메탄올을 이용하여 성장할 때의 세대 시간은 각각 25 시간과 8.3 시간이었다. pH 7.0 에서 성장한 세균들은 모두 지수성장기 중기에서 가장 높은 methanol dehydrogenase (MDH_) 의 활성을 나타내었고, MDH 함유량은 성장시기에 따른 변화를 보이지 않았다. 세포내 cytochrome c 는 정체기에서 높게 나타났고 pH 7.0 에서 성장한 세균에 더 많이 존재하였다. Putrescine 또는 spermidine 이 첨가된 pH 5.5 의 배지에서 성장한 세균에 더 많이 존재하였다. Putrescine 또는 spermidine 이 첨가된 pH 5.5 의 배지에서 성장한 세균에서는 putrescine 의 함량은 증가하였으나 spermine 의 함량은 감소하였고 spermidine 의 함량에는 변화가 없었다. Spermine 을 첨가한 배지에서 성장한 세균에서는 폴리아민함량에 변화가 없었다. Putrescine 또는 spermidine이 첨가된 배지에서 성장한 세균에서 MDH 와 hydroxypyruvate reductase 의 활성이 증가되었고 MDH 와 cytochrome c 의 함량에는 변화가 없었다. 폴리아민은 invitro 상태에서 MDH 와 hydroxypyruvate reductase 의 활성을 증가시키지 않았다. The generation time of Methylobacterium extorquens AMI growing on methanol at pH 5.5 and 7.0 was found to be 23 hand 8.3 h. respectively. The bacterium grown at pH 7.0 were found to contain more amounts of spermidine and putrescine than the cell grown at pH 5.5. Cells grown at both conditions exhibited strong methanol dehydrogenase (MDH) activity at the mid-exponential growth phase. The amounts of MDH. however. were found to be almost equal through all gro~1h phases. Cells growing at the stationary phase contained large amounts of cytochrome c. The cytochrome c content was higher in cells growing at pH 7.0 than the cells growing at pH 5.5. Cells growing at pH 5.5 in the presence of putrescine or spermidine contained increased amounts of putrescine. The level of spermine, however. was decreased and that of spermidine was not changed. Spermine added into the medium was found to have no effect on the level of cellular polyamines. Putrescine or spermidine added into the medium stimulated MDH and hydroxypyruvate reductase activities. but did not affect the contents of MDH and cytochrome c. It was found that preincubation of cell-free extracts with polyamines does not stimulate MDH and hydroxypyruvate reductase activities.

ASTM E681-04 표준에 따른가연성 냉매의 희박가연한계

박기정,우승규,정동수 대한설비공학회 2007 설비공학 논문집 Vol.19 No.10

In this study, lower flammability limits (LFLs) of three hydrocarbon refrigerants (R600a, R290, R1270) and two hydrofluorocarbon refrigerants (R152a, R32) and DME (RE170) are measured by the method proposed by ASTM E681-04 Standard. Flammability tests are carried out at three temperatures of 23℃, 60℃ and 100℃ and relative humidity 50%. Test results show that the present data for isobutane and propane obtained at 23℃ are similar to those found in the literature, confirming indirectly the reliability of the present test method and facility. For propylene, R152a, and R32, LFLs found in the literature differ considerably. Especially, the deviation of LFL of propylene is more than 30% among the literature data. The present data for propylene, R152a, and R32 agree with either of the data sets available. As the temperature increases from 23℃ to 100℃, LFLs of all refrigerants tested decrease. LFLs of most refrigerants tested in this study at 60℃ decrease by 0.1~0.3% as compared to those at 23℃. Also LFLs of most refrigerants tested in this study at 100℃ decrease by 0.1 ~0.3% as compared to those at 60℃.

가정용 빗물정원을 이용한 지붕빗물내 영양소 및 중금속 제거

박기정,박희수,조윤철,김성표 한국습지학회 2015 한국습지학회지 Vol.17 No.1

대부분의 강우가 여름철에 집중되는 국내 강우 특성은 여름철 집중호우에 따른 비점 오염물질의 수계로의 과대 유입에대한 우려를 높이고 있다. 국내 수계로의 오염원 유입특성이 대부분 비점오염원 형태인 것을 감안한다면 강우가 오염물질의 거동에 미치는 영향이 매우 크다고 할 수 있다. 특히 초기 우수의 경우 상당한 영양소와 중금속에 오염되어 있는 것으로 알려져 있기 때문에 이를 적절히 처리함과 동시에 재이용하기 위한 다양한 연구가 필요하다. 이를 해결하기위한 다양한 시설 중 빗물정원은 빗물양과 수질의 조절이 가능한 친환경적이며 효과적인 방안이다. 본 연구에서는 빗물정원에 효과적으로 적용 가능한 자연형 흡착여재를 개발하고 이를 적용하여 빗물이 빗물정원을 통과한 이후 유출수의 영양소 및 유기물(TN, TP, CODcr), 중금속 제거(Cu, Cd, Pb) 효율을 검토하였다. 이를 위하여 자연형 흡착여재인피트모스를 탄화시켜 오염물질 별 제거 흡착능을 살펴보았으며, 이를 이용한 삼단의 계단식 여재 시설을 구성하여 영양소 및 중금속 제거 변화 양상을 살펴보았다. 연구결과 피트모스는 더 높은 온도에서 탄화시켰을 경우 흡착능이 우수하였으며, 피흡착제의 농도가 낮을수록 흡착이 잘 되는 것으로 나타났다. 5개의 빗물정원에서의 인공강우 오염물질 제거효율을 분석한 결과, T-N, T-P, CODcr 모두 피트모스를 사용한 반응조가 제거율이 가장 높은 것으로 나타났다. 따라서 앞으로 빗물정원을 구성하는데 있어 피트모스를 탄화한 여재를 이용한다면 보다 효과적인 오염물질 저감효과를 얻을 수 있을 것이라 판단된다. In Korea, most rainfall events occur during summer which then leads to an increasing concern regarding high influxof non-point source pollutants since the pollutant loadings from these non-point sources are very significant. Inparticular, the first flush of roof-harvested rainfall is said to contain the most highest concentration of nutrients andheavy metals. Accordingly, it is important to develope the possible water quality management options in treating thecontaminants and considering reclaimed water reuse. The rain garden could be one of suitable alternatives inaddressing this issue. In this study, the development of an effective adsorption media and its application to a lab-scalerain garden was tested to evaluate the removal rate of various nutrient and organic matter (TN, TP, CODcr), andheavy metals (Cu, Cd, Pb). Results showed that carbonized peatmoss produced at higher temperature have betteradsorption capacity as compared to the one produced at a lower temperature. When the carbonized peatmoss wasapplied as rain garden media, the highest removal of TN, TP, and CODcr was observed compared to no carbonizedpeatmoss applied rain garden. Therefore, this study showed that the carbonized peatmoss would be effectively appliedto the rain garden for removing nutrients and heavy metals from roof-harvested rainwater.