• 한국전산유체공학회지
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• 제21권4호
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• pp.33-39
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• 2016

Generally, thermal analysis of spent fuel storage cask has been conducted using the porous media and effective thermal conductivity model to simplify the structural complexity of spent fuel assemblies. As the fuel assembly is composed of two regions; active fuel region corresponding to UO2 pellets and unactive fuel region corresponding to the top and bottom nozzle, the heat transfer performance can be influenced depending on porous media application at these regions. In this study, numerical analysis on concrete storage cask of spent fuel was performed to investigate heat transfer effects for two cases; one was porous media application only to active fuel region(case 1) and the other one was porous media to whole length of fuel assembly(case 2). Using computational fluid dynamics code, the three dimensional, 1/4 symmetry model was constructed. For two cases, maximum temperatures for each component were evaluated below the allowable limits. For the case 1, maximum temperatures for fuel cladding, neutron absorber and baskets inside the canister were slightly higher than those for the case 2. In particular, even though the helium flows with low velocity due to buoyant forces occurred at the top and bottom of unactive fuel region, treating only active fuel region as the porous media was ineffective in respect of the heat removal performance of concrete storage cask, implying a conservative result.

• 대한지역사회영양학회지
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• 제9권1호
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• pp.58-65
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• 2004

The purpose of this research was to examine the relationship between the plasma LDL particle size and blood lipid profile, dietary factors and anthropometric values (body mass index, waist circumference and waist/hip ratio). The subjects were 173 adults aged 23 to 81 years, selected from the Outpatient Clinic and Cardiovascular Department of the Seoul Municipal Hospital. Dietary data were obtained using a 3-day food record and analyzed using Korean and US nutrient databases. The subjects were divided into three groups by LDL particle size : type A (large buoyant LDL, > 25.5 nm, n=96), type I (Intermediate LDL,$25.2\leq-\leq25.5$ nm, n=18), and type B (small dense LDL, < 25.2 nm, n=59) groups. The type B group had higher age, waist circumference, and waist/hip ratio (WHR) than the type A and type I groups. Serum concentration of triglyceride, Apo B, LDL/HDL cholesterol ratio and atherogenic index were significantly higher in the type B group as compared to those in the other two groups. HDL cholesterol level and Apo A-I/Apo B ratio were significantly lower in the type B group than the other two groups. The plasma LDL particle size was highly correlated with triglyceride (r= -0.450), Apo B (r= -0.402) and HDL cholesterol (r= 0.418). However, there was no correlation between plasma LDL particle size and dietary intakes. This study showed that small dense LDL was an important biochemical risk factor that was associated with other risk factors.

• 한국터널지하공간학회 논문집
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• 제18권6호
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• pp.581-591
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• 2016

최근 사회기반시설의 투자효율성을 높이기 위하여 평상 시 도로터널로 운영되지만 홍수 시 수로로 이용되는 수로 도로 다목적 터널의 계획이 시도되고 있다. 이러한 다목적 터널은 수로터널로의 이용이 한시적이기 때문에 내수압과 지하수위가 일정하지 않아 터널 내부와 외부의 압력변화가 상당할 수 있다. 특히 지하수위 아래에 건설 된 다목적 터널의 경우 장기간 운영 중에 발생하는 계절적 압력변화는 터널에 반복하중으로 작용하여 구조물과 인접지반의 열화로 이어질 가능성이 있다. 본 연구에서는 다목적 터널의 외부 및 내부 수위조건에 따라 발생할 수 있는 구조물의 거동특성을 모형실험 및 수치해석을 통하여 조사하였다. 그 결과 수위변화로 인한 터널 거동의 주 원인은 부력이며, 터널 내부 및 외부의 반복적인 수위변화는 터널 주변지반의 이완영역을 확대시키는 것으로 나타났다. 따라서 다목적 터널의 설계 시 수위변화에 따른 영향검토가 필요하며 경우에 따라 저항성을 유지시킬 수 있는 대책의 검토가 필요하다.

• 한국임상수의학회지
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• 제20권2호
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• pp.150-154
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• 2003

진주 지역에서 1000 여두의 생후 1주령 포유 자돈군에 심한 설사증이 발생하였던바 소장조직으로부터 RNA를 추출한 후 reverse transcription-polymerase chain reaction을 실시하였던 결과, porcine epidemic diarrhea (PED) virus (PEDV)의 N 유전자가 검출되어 PED로 진단되었다. Trypsin (10ug/ml)을 첨가한 배지에서 Vero 세포를 배양하면서 장조직으로부터 바이러스 분리배양을 시도하였던 결과 2회의 blind passage 후에 PEDV를 분리할 수 있었다. 따라서 이 분리주를 Chinju99로 명명하였으며, Chinju99주의 생물학적 및 물리화학적 성상을 조사하였던 결론은 다음과 같다. Chinju99주는 전자현미경 소견에서 비정형의 타원형 입자로서 표면에 spike 구조를 가지고 있었으며, Vero 세포내 배양시에 점진적으로 원형변성, 합포체형성 등의 세포변성 소견을 나타내었다. 또한 20% ether, 5% chloroform에서 불안정하였으며 pH 4-7의 산성조건에서는 안정성을 나타내었다. 동시에 $50^{\circ}C$에서 180분간 처리 후에도 감염성이 유지되었고 sucrose 용액에서의 부유밀도가 1.180g/ml으로서, coronavirus의 전형적인 생물학적 및 물리화학적 성상을 나타내었다.

• 한국물환경학회지
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• 제34권2호
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• pp.210-215
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• 2018

It is difficult to count colonial cyanobacteria Microcystis cells since the thickness of colonies is constrained by amorphous mucilage, making it impossible to estimate the number of cells. Disaggregation of Microcystis colonies into single cell is needed to improve the accuracy and precision of cell density estimation of naturally collected samples. Uultrasonic treatment method is commonly used owing to the simplicity and immediacy of the procedure. However, amplitude, frequency, and duration of ultrasonic treatment also cause cell loss during the experiment. Optimal ultrasonic treatment has not been standardized yet. Therefore, the objective of this study was to investigate optimal ultrasonic treatment by analyzing cell density and colony numbers. We collected colonial Microcystis from Changnyeong-Haman weir area in Nakdong River during harmful algal boom period from September to October in 2017. Ultrasonic treatment method was applied to disrupt colonies into single cells to enumerate cell density. Among treatment conditions, results from continuously treated for 100 seconds were found to be the optimum to reduce colonies to a suspension of single cell without cell losses under high and low density of Microcystis cells. Lugol iodine fixed cells followed by sonication showed less negative impact of cell damage within the optimal treatment time (100 seconds). Furthermore, disaggregated cells treated by sonication enables microscopic observation more easily since gas vacuoles were collapsed to facilitate sedimentation of cells under the counting chamber for quantitative enumeration of buoyant Microcystis cells.

• 미생물학회지
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• 제39권2호
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• pp.118-122
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• 2003

바이러스 조립 과정 기작 연구를 위한 좋은 재료인 박데리오파아지 P2-P4시스템에 이용될 벡터 플라스미드를 개발하기 위하여, P4 ash8 sid71을 출발 물질로 삼아 새로운 P4 유도체 벡터를 조성하였다. 유전자 재조합 기법을 써서 쉽게 선택 가능한 tetracyclin내성 유전자(tetR)를 도입하고 플라스미드P 4의 크기를 조절하였다. 이를 통해 얻어진 P4 ash8(sid7l) tetR은 12.09 kb의 크기를 가지며, 필요할 때 P2로 induction하면 생물학적 활성을 가지는 박데리오파아지로 전환 가능하였다. 전환된 파아지의 burst size를 결정하고, CsCi 부양균등밀도 편차실험을 수행하였다. 균등밀도 실험 분포도에서 P2크기 파아지 머리의 packaging 상한을 추정할 수 있었다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.142-149
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• 2003

Blind hydraulic backfilling is a commonly used technique for subsidence control of the strata over unapproachable waterlogged underground excavations. In this investigation model studies on all the three variants of this technique, namely, hydro-pneumatic or air-assisted gravity backfilling, pumped-slurry backfilling and simple gravity backfilling, have been carried out in fully transparent models of the underground excavations. On examination of the filling process, it was revealed that in all the three cases, the basic process of filling occurs by sand transport along one or more meandering channels. The relative influence of sand, water and air flow rates on the area of filling from a single inlet point and the hydraulic pressure loss per unit length were studied in details. In hydro-pneumatic backfilling process, the air bubbles while moving upward through the meandering channels provide an additional buoyant force over and above the available hydraulic head. In this way the area of filling from a single borehole may be quite large even at small flow rates of water. During actual field implementation the injected air, if not released completely from the rise side holes, may cause troubles by way of creating potholes on the surface. The pumped-slurry technique has shown its capability of filling a relatively larger area at faster rate, especially when high-volume, low-pressure method was selected. But simple gravity filling was also found to be equally effective method as slurry pumping, especially when flow rates were high. In the second and third method discussed above, examination of variations of injection pressure was also done and its relation with physical phenomenon was also attempted. Some empirical relationships were also developed using multivariate regression with a view to help the practicing engineers.

• 한국물환경학회지
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• 제33권4호
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• pp.449-459
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• 2017

In Geum River of Korea, three multi-purpose weirs were built at the downstream of Daecheong Reservoir during the Four Major River Restoration Project (FMRRP). The weirs have altered the hydraulic characteristics of the river, and consequently transformed the large areas of flowing ecosystem to deep and wide stagnant environment. In every summer, a thermal stratification occurred near the Baekje Weir having mean depth of 4.0 m, and the surface algal blooms dominated by buoyant cyanobacteria have been frequently formed after the FMRRP. The objective of this study was to investigate the relationship between flow velocity and thermal stability of the waterbody using a three-dimensional (3D) hydrodynamic model (EFDC+) after calibration against the thermistor chain data obtained in 2014. A new Sigma-Zed vertical grid system of EFDC+ that minimize the pressure gradient errors was used to better simulate the thermodynamics of the waterbody. The model reasonably simulated the vertical profiles of the observed water temperatures. The vertical mean flow velocity and the Richardson Number (Ri) that represents the stability of waterbody were estimated for various management water levels and flow rates scenarios. The results indicated that the thermal stability of the waterbody is mostly high ($Ri{\gg}0.25$) enough to establish stratification, and largely depend on the flow velocity. The critical flow velocity that can avoid a persistent thermal stratification was found to be approximately 0.1 m/s.

• 한국수산과학회지
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• 제37권6호
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• pp.478-484
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• 2004

On 11 June 1991, eggs from the brood stock of small yellow croaker (Larimichthys polyactis) were artificially fertilized using the standard dry method and were hatched. Each of the fertilized eggs (1.1-1.2 mm in diameter) had an oil globule and was transparent and buoyant. The fertilized eggs hatched in a range of water temperatures $(17.5-20.3^{\circ}C)$ 44 hrs after fertilization. The total lengths of the newly hatched larvae were 3.1-3.3 mm, and these hatchlings had 31 myotomes (10+21). Melanophores and yellow-brown chromatophores were concentrated on the head, at the ventral part of the yolk, and in the middle of the tail. Four days after hatching, the larvae completely absorbed the yolk and became flexions of 5.1-5.5 mm in total length. Fifteen days after hatching, one spine (the anterior tip of the maxillary) appeared in the upper jaw and three spines developed at the upper parts of the eyes and on the posterior part of the head. At this stage, the larvae were approximately 8.3 mm long. Thirty-nine days after hatching, juveniles (1.9-3.4 mm in total length) had a pointed tail fin. By 66 days after hatching, the juvenile fish (about 4.0-6.5 mm in total length) were similar to adult fish in body shape. The larvae of L. polyactis could be distinguished from those of L. croacea by two distinct characteristics: the large number of vertebrae (28-29), and a relatively small bony ridge on the occipital region of the head.

• 대한기계학회논문집B
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• 제20권2호
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• pp.624-631
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• 1996

가솔린 화재의 소화과정을 규명하기 위하여 부력과 순수확산에 의해서만 연료와 산화제가 혼합되는 순수확산화염을 대항으로 수분무에 의한 소화실험을 체계적으로 수행하여 다음과 같은 결론을 얻었다. 1) 수분무는 특정 조건에서 수분무가 없을 때인 자연연소상태에 비하여 더 높은 값의 연소율을 가지게 되어, 오히려 화재의 연소를 촉진하게 된다. 2) 수분무시 연소율은 자연연소상태보다 더 높은 값으로 증가하다가 어느 순간 연료표면의 냉각조건이 충분히 이루어지면 소화기 일어나게 된다. 30 수분무에 의해 유입되는 공기는 분무 자체와 함쎄 화염을 반경방향으로 흐트러지게 함으로써 연료와 공기와의 접촉면적을 증대시켜 연소를 촉진하는 반면, 분무수가 연료 표면에 쉽게 도달할 수 있도록하여 연료표면을 보다 잘 냉각시키게 된다. 즉 주위공기의 유입은 연소율의 증가 및 감소에 영향을 미친다. 4) 본 실험조건에서는 분무수의 입경이 약 40.mu.m 이하인 액적들은 화염구역내에서 증발하거나 그 경로가 바뀌어 연료 표면에 도달되지 못함을 발견하였다. 5) 본 연구와 같이 주로 냉각작용에 의하여 화염이 소화되는 경우에는, 화염자체의 냉각효과 보다는 연료표면의 냉각에 의한 효과가 지배적임을 알 수 있었다.