• 대한기계학회논문집B
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• 제29권10호
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• pp.1101-1110
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• 2005

In this paper we present the numerical results of the behavior of the horizontal vortex generated by ejecting a liquid vertically upward from an orifice into the bulk fluid above the orifice. The numerical calculation has been performed for the axi-symmetric Navier-Stokes equation. A simple flow-visualization experiment was also conducted to qualitatively verify the numerical solutions. Three cases of the flow configurations studied in this paper are; firstly, the vortex was generated without any background rotation, secondly, the vortex was made under a full background rotation, and thirdly, the vortex was made during the spin-up process such that only the region adjacent to the side wall was set into motion viewed in the inertial frame of reference. It was shown that the swirl flow at the inlet boundary affects considerably the formation and development of the vortex for the second case. In the third case, it was remarkable to see that the vortex cannot penetrate into the region near to the side wall of the tank, because of the strong swirl flow and corresponding high pressure gradient in the region.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.211-221
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• 1998

Thermal behavior on the cylinder block of a 4-cylinder, 4-stroke 2.0L SOHC gasoline engine was numerically and experimentally analyzed. The numerical calculation was performed using the finite element method. The cylinder block was modelled as a three dimensional finite element by considering its geometry. The physical domain was devided into hexahedron elements. 16 thermocouples were installed at points of 2mm inside from cylinder wall near top ring of piston in cylinder block, which points have suffered major thermal loads and suggested as proper measurement points for engine design by industrial engineers. Under full load and 9$0^{\circ}C$ coolant temperature condition, temperature behavior of cylinder block according to engine speed were analyzed. The results showed that temperature rose gradually to conform to a function of 2nd~4th order of engine speed at intake side, exhaust and siamese side, respectively. As engine load was changed from 100 to 50% by 25% step, temperature curve also conformed to 2nd~7th order function of engine speed. Temperature differences by load condition were similar among 100, 75% and 50%. Under full load and coolant temperature of 11$0^{\circ}C$, temperature behavior were also analyzed and the result also showed conformance to 2n d~7th order function of engine speed. Temperature curve was transferred in parallel upwards corresponding coolant temperature rise.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.294-299
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• 2008

Steam reforming of methane is the most wide spread method for hydrogen production. It has heed studied more than 60 years. methane reforming has advantages in technological maturity and economical production cost. Using a high-temperature solar thermal energy is an advanced technology in Steam reforming process. The synthesis gas, the product of the reforming process, can be applied directly for a combined cycle or separated for a hydrogen. In this paper, hydrogen conversion rate of a solar chemical reactor is calculated using commercial CFD program. 2 models are considered. Model-1 is original model which is designed from the former researches. And model-2 is ring-disk set of baffle is inserted to enhance the performance. The solar chemical reactor has 3 inlet nozzle at the bottom of the side wall near quartz glass and an exit is located at the top. Methane and steam is premixed with 50:50 mole fraction and goes into the inside. Passing through the porous media, the reactants are conversed into hydrogen and carbon monoxide.

• Biomolecules & Therapeutics
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• 제22권5호
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• pp.420-425
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• 2014

Esophageal reflux of gastric contents causes esophageal mucosal damage and inflammation. Recent studies show that oxygen-derived free radicals mediate mucosal damage in reflux esophagitis (RE). Chlorogenic acid (CGA), an ester of caffeic acid and quinic acid, is one of the most abundant polyphenols in the human diet and possesses anti-inflammatory, antibacterial and anti-oxidant activities. In this context, we investigated the effects of CGA against experimental RE in rats. RE was produced by ligating the transitional region between the forestomach and the glandular portion and covering the duodenum near the pylorus ring with a small piece of catheter. CGA (10, 30 and 100 mg/kg) and omeprazole (positive control, 10 mg/kg) were administered orally 48 h after the RE operation for 12 days. CGA reduced the severity of esophageal lesions, and this beneficial effect was confirmed by histopathological observations. CGA reduced esophageal lipid peroxidation and increased the reduced glutathione/oxidized glutathione ratio. CGA attenuated increases in the serum level of tumor necrosis factor-${\alpha}$, and expressions of inducible nitric oxide synthase and cyclooxygenase-2 protein. CGA alleviates RE-induced mucosal injury, and this protection is associated with reduced oxidative stress and the anti-inflammatory properties of CGA.

• 센서학회지
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• 제22권2호
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• pp.156-161
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• 2013

This study was aimed to implement the electroglottography (EGG) system for analyzing fundamental frequency of the phonation. EGG was recorded from the conductance between ring electrodes attached to the neck skin area near thyroid cartilage with high frequency carrier electric signals during vocalization, and voice signal was recorded with microphone simultaneously. EGG and voice signals were transmitted to the audio port in PC and recorded with stereo sound recording program. From the digitized data, several parameters such as pitch, jitter, shimmer, CQ and SQ were analyzed from the vowel sounds. For the voice training, sound fundamental frequency was displayed during the vocalization and singing a song using pitches analyzed from the EGG. The system implemented in this study could be used for vocal exercise.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3005-3008
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• 2014

Human ChlR1 protein (hChlR1), a member of the cohesion establishment factor family, plays an important role in the segregation of sister chromatids for maintenance of genome integrity. We previously reported that hChlR1 interacts with hFen1 and stimulates its nuclease activity on the flap-structured DNA substrate covered with RPA. To elucidate the relationship between hChlR1 and Okazaki fragment processing, the effect of hChlR1 on in vitro nuclease activities of hFen1 and hDna2 was examined. Independent of ATPase activity, hChlR1 stimulated endonuclease activity of hFen1 but not that of hDna2. Our findings suggest that the acceleration of Okazaki fragment processing near cohesions may aid in reducing the size of the replication machinery, thereby facilitating its entry through the cohesin ring.

• Bulletin of the Korean Chemical Society
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• 제28권2호
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• pp.207-210
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• 2007

To identify structural or functional common subunit(s) in the CP1 (editing) domains of class Ia tRNA synthetases, five available structures were compared and analyzed. Through the sequence alignments and structural overlapping of the CP1 domains, three conserved regions were identified near the amino acid binding site in the editing domain. Structural overlapping of the three subunits clearly showed the existence of three common structural subunits in all of the five editing RS structures. Based on the established experimental results and our modeling results, it is proposed that subunits 1 and 3 accommodate the incoming amino acid binding, while subunit 2 contributes to the interactions with the adenosine ring of the A76 to stabilize the overall tRNA binding. Since these subunits are critical for the editing reaction, we expect that these key structures should be conserved through the most class Ia editing RSs.

• Composites Research
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• 제13권4호
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• pp.75-82
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• 2000

유리섬유/에폭시 복합재료로 피막한 유리판의 표면파괴거동을 연구하기 위하여 미소강구 충격실험을 수행하였다. 본 연구에서는 다섯 종류의 재료, 단순소다유리판(soda-lime glass plates), 유리섬유/에폭시박막(glass/epoxy lamina)을 1층 접착, 비접착한 시편과 박막을 3층 접착, 비접착한 시편을 사용하였다. 충격속도 범위 40∼120m/s에서 유리판 배면에서의 최대 응력과 흡수파괴에너지를 측정하였다. 충격 속도증가에 따라 링균열, 콘균열, 레이디얼 균열이 시편 내부에서 발생하였다. 복합재료 박막으로 피막한 결과, 소다유리판의 균열은 현저히 감소하였으며 측정한 최대 응력과 흡수파괴에너지를 이용하여 표면 파괴거동 특성을 평가할 수 있었다.

• 한국결정성장학회지
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• 제6권1호
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• pp.11-18
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• 1996

Czochralski법으로 성장된 대구경(8인치 이상) 규소 단결정속에 폰재하는 결정 결 함을 규명하였다. Ring형 산화 적충 결함(Oxidation Induced Stacking Faults, 일명 OISF)의 발생 형태를 조사하였다. Minority life time을 mappmg하여 본 결과, rmg형 OISF의 폰재는 재료의 전기적 성질에 영향을 미칠 가능성이 높은 것으로 확인되었다. OISF의 핵 생성에 미치는 냉각 속도의 영향을 조사한 결과 homogeneous적 핵 생성 및 성장 현상을 확인할 수 있었다. 또한 COP(Crystal Originated Particle)의 주원인인 FPD(Flow Pattern Defects)의 발생은 용 체의 응고 속도에 크게 화우됨을 발견하였다. 이들 결함의 상반된 발생 현상의 제어를 위하여 는 인상 속도는 느리게, 또한 $950^{\circ}C$ 근처에서의 냉각속도는 빠르게 하는 것이 바람직한 것으로 결함 발생 제어 모델이 제시되었다.

• 한국수정란이식학회지
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• 제32권3호
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• pp.105-109
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• 2017

Autophagy is an intracellular degradation and recycling system. Oocyte maturation is dynamic process, in which various proteins should be synthesized and degraded. In our previous study, we reported the loci of autophagosome and dynamics of autophagic activity in porcine oocytes during in vitro maturation. In this study, we verified loci of autophagosome in porcine follicular cumulus-oocyte complex by detection of microtubule-associated protein 1A/1B-light chain 3 (LC3) which is the reliable marker of autophagosome. Porcine ovary including various sizes of follicles was fixed within 1 hour after collection from slaughterhouse. After fixation, immunohistochemistry was conducted on sliced ovary tissue containing various sizes of follicles by using LC3 antibody. As a result, LC3 signal was clearly detected in both cumulus and oocytes of various sizes of follicles. We also found ring shaped signal which represent autophagosome near oocyte membrane. Most of the signals in oocytes were localized nearby cellular membrane while evenly dispersed in cumulus cells. Therefore, this result suggests that autophagy occurs in porcine COCs (cumulus-oocyte complexes) at follicular stage.