• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제32권4호
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• pp.287-294
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• 2006

The secondary correction of cleft lip nasal deformity (CLND) presents difficult surgical problems. Characteristically, nostrils are asymmetric. The present study was aimed to examine and compare the effect of Straith's alar web Z-plasty, Millard's alar web Z-plasty, alar web excision, and lateral V-Y advancement of the alar base for augmentation of the nostril with or without lengthening the columella in CLND. The subjects were 28 patients with unilateral cleft lip, who had secondary nostril correction. The nostril correction methods were Straith's alar web Z-plasty, Millard's alar web Z-plasty, alar web excision, and lateral V-Y advancement of the alar base. Facial photographs were taken before and 20 days after the operation. By using Adobe photoshop, the columella length and the nostril width were measured from the facial frontal photograph and Worm's eye view. The degree of improvement was calculated and statistically analyzed. The degree of improvement of the columella length using Straith's alar web Z-plasty was 70.20%. And then Millard's alar web Z-plasty was 55.01%, alar web excision was 39.93%, and lateral V-Y advancement of the alar base was 16.38% in order. The degree of improvement of the nostril size using lateral V-Y advancement of the alar base was 55.26%. And then alar web excision was 52.72%, Millard's alar web Z-plasty was 34.86%, and Straith's alar web Z-plasty was 16.06% in order. Straith's alar web Z-plasty and Millard's alar web Z-plasty resulted in elongation of the columella, equalization of asymmetrical nostril, and enlargement of small nostrils. Alar web excision enlarged nostrils and restored symmetry. Lateral VY advancement of the alar base increased nostril width and enlarged nostrils. These results indicate that the correction of nostrils improve the shape and the symmetry of the nostrils in CLND.

• 한국입자에어로졸학회지
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• 제9권2호
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• pp.103-110
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• 2013

The electrostatic precipitator (ESP) has been used for degrading atmospheric pollutants. These devices induce the electrical forces to facilitate the removal of particulate pollutants. The ions travel from the high voltage electrode to the grounded electrode by Coulomb force induced by the electric field when a high voltage is applied between two electrodes. The ions collide with gas molecules and exchange momentum with each other thus inducing fluid motion, electrohydrodynamic (EHD) flow. In this study, for the simulation of electric field and EHD flow in ESPs, an open source EHD solver, "espFoam", has been developed using open source CFD toolbox, OpenFOAM(R) (Open Field Operation and Manipulation). The electric potential distribution and ionic space charge density distribution were obtained with the developed solver, and validated with experimental results in the literature. The comparison results showed good agreement. Turbulence model is also incorporated to simulate turbulent flow; hence the developed solver can analyze laminar and turbulent flow. In distributions of electric potential and space charge, the distributions become distorted and asymmetric as the flow velocity increases. The effect of electrical drift flow was investigated for different flow velocities and the secondary flow in a flow of low velocity is successfully predicted.

• Membrane and Water Treatment
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• 제7권3호
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• pp.257-275
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• 2016

The enantiomeric and racemic effects of tartaric acid (TA) on the properties of polysulfone (PSn) ultrafiltration membranes were studied in terms of morphology and hydrophilicity (HPCT) of membrane. Asymmetric membranes were prepared by direct blending of polyvinyl pyrrolidone (PVP) with D-TA and DL-TA in membrane casting solution. FTIR analysis was done for the confirmation of the reaction of PVP and TA in blended membranes and plain PSn membranes. Scanning electron microscope (SEM), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM) were used for analyzing the morphology and structure of the resulting membranes. The membranes were characterized in terms of pure water flux (PWF), hydraulic permeability and HPCT. PWF increased from $52L/m^2h$ to $79.9L/m^2h$ for plain and D-TA containing PSn membrane, respectively. Water contact angle also found to be decreased from $68^{\circ}$ to $55^{\circ}$. In Additionally, permeation and rejection behavior of prepared membranes was studied by bovine serum albumin (BSA) solution. A considerable increase in BSA flux (from $19.1L/m^2h$ for plain membrane to $32.1L/m^2h$ for D-TA containing membrane) was observed. FESEM images affirm that the pore size of the membranes decreases and the membrane permeability increases from 0.16 to 0.32 by the addition of D-TA in the membrane. D-TA increases the HPCT whereas; DL-TA decreases the HPCT of PSn membrane. PVP (average molecular weight of 40000 Da) with D-TA (1 wt%) gave best performance among all the membranes for each parameter.

• 한국전기전자재료학회논문지
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• 제29권6호
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• pp.348-352
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• 2016

In this paper, GaN film was grown on AlN/PSS by hydride vapor phase epitaxy compared with GaN on planar sapphire. Thin AlN layer for buffer layer was deposited on patterned sapphire substrate (PSS) by metal organic chemical vapor deposition. Surface roughness of GaN/AlN on PSS was remarkably decreased from 28.31 to 5.53 nm. Transmittance of GaN/AlN grown on PSS was lower than that of planar sapphire at entire range. XRD spectra of GaN/AlN grown on PSS corresponded the wurzite structure and c-axis oriented. The full width at half maximum (FWHM) values of ${\omega}$-scan X-ray rocking curve (XRC) for GaN/AlN grown on PSS were 196 and 208 arcsec for symmetric (0 0 2) and asymmetric (1 0 2), respectively. FWHM of GaN on AlN/PSS was improved more than 50% because of lateral overgrowth and AlN buffer effect.

• 멤브레인
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• 제15권1호
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• pp.22-33
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• 2005

비대칭 폴리비닐리덴플루오라이드(PVDF) 막을 상전환법으로 제조하였다. 도포용액은 PVDF를 용매인 N-ethyl-2-pyrrolidone (NMP)와 비용매인 1,4-dioxane, diethyleneglycol dimethyl ether (DGDE), acetone, (equation omitted)-butyrolactone(GBL)의 혼합용매에 녹여서 제조한다. 여러 첨가제가 도포용액 특성, 투과특성과 막 구조에 미치는 영향을 조사하였다. 응고제인 물과 1,4-dioxane, DGDE, acetone과의 상용성이 NMP보다 낮아서 기공크기가 작아진다. 첨가제의 양을 조절하여 기공크기를 변화시켰다. 혼합용매(수계 및 비수계)가 막의 투과성능에 미치는 영향을 살펴보았다. 용액점도뿐만 아니라 표면장력도 용매 투과특성에 영향을 끼침을 알 수 있었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.287-290
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• 2005

Once hot forgings for automotive parts such as wheel bearing flange to which cyclic asymmetric bending stress is continuously applied are produced, it is necessary to control their microstructure to obtain superior mechanical properties. It is however hard to control the microstructure uniformly because the strength is reduced as coarsening of ferrite grains. To investigate the microstructural alteration according to process variables during hot working, the variation of the ferrite grain size was studied by utilizing of the computer aided servo-hydraulic Gleeble tester which is hot deformation behavior reproduction equipment. In addition, the effect of the ferrite grain size of raw material on the austenite grain behavior of hot forgings was also examined. The rolling contact fatigue resistance of the induction hardened SAE 1055 steel was compared with the occasion of the same condition of SAE52100 bearing steel. As a result, it was confirmed that the ferrite grain sizes of the forgings depend on the heating temperature and cooling start temperature during hot forging and cooling processes. The induction hardened SAE1055 steel showed a superior rolling contact fatigue resistance to the induction hardened SAE52100 steel. The reason is that SAE1055 steel is freer from the material defect such as segregation than the comparative steel.

• 한국광학회지
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• 제26권2호
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• pp.103-109
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• 2015

진폭 분할식 간섭계에서는 입력 빔을 빔가르개(BS)로 분리하고 서로 다른 경로를 거쳐 전파하게 한 다음 두 빔을 중첩시켜 간섭 효과를 일으킨다. 본 논문에서는 손실이 없는 유전체 층들로 이루어진 BS에서 반사와 투과로 분리된 두 광파 사이의 위상관계에 대해 연구하였다. 적절한 기준면에 대해 위상을 정의하면 BS의 층 구조에 관계 없이 투과광과 반사광 사이에는 일정한 위상차가 있다는 것을 알 수 있었다. 이 결과는 일반적인 Stokes 관계식으로 명백히 주어지나, 본 논문에서는 대표적인 대칭적/비대칭적 구조를 가진 두 BS 층에 대해 수치적으로 이를 증명해 보았다. 이 위상 관계로 인해 간섭계에서는 출력광의 중첩 상태(보강 혹은 상쇄 간섭)가 결정되고, 빛 에너지는 보존된다는 당연한 결과를 얻을 수 있었다.

• Animal Bioscience
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• 제34권5호
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• pp.880-885
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• 2021

Objective: Omasum is an important site for the absorption of short chain fatty acids. The major route for the transport of acetate is via sodium hydrogen exchanger (NHE). However, a discrepancy in the symmetry of sodium and acetate transport has been previously reported, the mechanism of which is unclear. In this study, we investigated the possible role of carbonic anhydrase (CA) for this asymmetry. Methods: Omasal tissues were isolated from healthy sheep (N = 3) and divided into four groups; pH 7.4 and 6.4 alone and in combination with Ethoxzolamide. Electrophysiological measurements were made using Ussing chamber and the electrical measurements were made using computer controlled voltage clamp apparatus. Effect(s) of CA inhibitor on acetate and sodium transport flux rate of Na22 and 14C-acetate was measured in three different flux time periods. Data were presented as mean±standard deviation and level of significance was ascertained at p≤0.05. Results: Mucosal to serosal flux of Na (JmsNa) was greater than mucosal to serosal flux of acetate (JmsAc) when the pH was decreased from 7.4 to 6.4. However, the addition of CA inhibitor almost completely abolished this discrepancy (JmsNa ≈ JmsAc). Conclusion: The results of the present study suggest that the additional protons required to drive the NHE were provided by the CA enzyme in the isolated omasal epithelium. The findings of this study also suggest that the functions of CA may be exploited for better absorption in omasum.

• 국제지역연구
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• 제14권3호
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• pp.62-84
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• 2010

본 논문은 중국, 홍콩, 대만 주식시장들 사이의 동태적 상호의존성을 연구한다. 이를 위하여 아시아 금융위기가 그러한 상호의존성의 구조전환점인지를 검토하고, 이를 아시아 금융위기를 기준으로 세 가지 분석기간을 설정하여 수익률과 변동성의 정보전이효과를 분석한다. 전체기간을 대상으로 한 실증분석 결과 세 시장 수익률 평균과 비대칭 변동성 사이에 정보전이효과가 유의하게 존재한다는 증거가 발견되었다. 이는 세 시장 간에 정보전이와 비대칭적 변동성이 존재한다는 것을 암시한다. 또 수익률 평균과 비대칭 변동성 사이에 존재하는 정보전이효과의 크기가 금융위기 이후 증가한 것으로 나타났다. 이러한 사실은 아시아 금융위기 이후 중국, 홍콩, 대만 주식시장의 통합이 더 강화된 것을 의미한다. 특히 변동성 정보전이효과의 비대칭성이 금융위기 이후 더 심화된 것으로 나타났다. 이러한 사실은 긍정적 충격보다 부정적 충격이 대중국 주식시장 변동성에 미치는 영향이 금융위기 이후 더 심화된 것을 의미한다. 결론적으로 아시아 금융위기가 중국, 홍콩, 대만 주식시장의 정보전이와 비대칭성을 심화시킨 것으로 판단된다.

• 국제지역연구
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• 제14권3호
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• pp.86-107
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• 2010

한 경제의 변동성과 성장률간의 관계에 대한 기존의 경험적 연구에서는, 두 변수 사이의 관계가 양의 부호를 가지는지 아니면 음의 부호를 가지는지에 대해 명확한 결론을 찾지 못하였다. 본 논문에서는 기존 연구결과의 모호성을 설명하는 한 요인으로서, 기존의 경험적 연구에서 사용한 추정모형이 오설정(誤設定)(misspecified)되었을 가능성을 제기한다. 만일 경기변동상의 확장기와 수축기에 따라 두 변수간 관계의 부호가 상이하다면, 양자간 관계를 대칭적으로 설정한 기존의 연구모형에서는 유의한 관계를 추정해 낼 수 없기 때문이다. 본 연구는, 변동성의 증가가 성장률에 미치는 영향이 경기변동국면에 따라 다르다는 가설로부터 출발한다. 영국의 월별산업생산 자료를 이용하여 일련의 ARCH 류 모형을 추정한 결과, 경제가 확장기에 있을 경우에는 변동성과 성장률간의 관계가 유의한 양의 부호를 가지는 반면 수축기에서는 변동성의 증가가 성장률을 유의하게 낮추는 현상을 발견하였다. 또한 변동성과 성장률간의 이와 같은 비대칭적 관계가, 두 변수 사이에 양방향으로 존재하는 상관관계가 아니라 변동성으로부터 성장률로 작용하는 인과관계임을 지지하는 결과도 얻었다.