• 한국환경과학회지
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• 제26권5호
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• pp.621-638
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• 2017

Meteorological characteristics related to variations in ozone ($O_3$) concentrations in the Korean peninsula before, during, and after Typhoon Talas (1112) were analyzed using both observation data and numerical modeling. This case study takes into account a high $O_3$ episode (e.g., a daily maximum of ${\geq}90ppb$) without rainfall. Before the typhoon period, high $O_3$ concentrations in the study areas (e.g., Daejeon, Daegu, and Busan) resulted from the combined effects of stable atmospheric conditions with high temperature under a migratory anticyclone (including subsiding air), and wind convergence due to a change in direction caused by the typhoon. The $O_3$ concentrations during the typhoon period decreased around the study area due to very weak photochemical activity under increased cloud cover and active vertical dispersion under a low pressure system. However, the maximum $O_3$ concentrations during this period were somewhat high (similar to those in the normal period extraneous to the typhoon), possibly because of the relatively slow photochemical loss of $O_3$ by a $H_2O+O(^1D)$ reaction resulting from the low air temperature and low relative humidity. The lowest $O_3$ concentrations during the typhoon period were relatively high compared to the period before and after the typhoon, mainly due to the transport effect resulting from the strong nocturnal winds caused by the typhoon. In addition, the $O_3$ increase observed at night in Daegu and Busan was primarily caused by local wind conditions (e.g., mountain winds) and atmospheric stagnation in the wind convergence zone around inland mountains and valleys.

• International Journal of Fluid Machinery and Systems
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• 제7권1호
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• pp.34-41
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• 2014

Computational fluid dynamics (CFD) and particle image velocimetry (PIV) are commonly used techniques to evaluate the flow characteristics in the development stage of blood pumps. CFD technique allows rapid change to pump parameters to optimize the pump performance without having to construct a costly prototype model. These techniques are used in the construction of a bi-ventricular assist device (BVAD) which combines the functions of LVAD and RVAD in a compact unit. The BVAD construction consists of two separate chambers with similar impellers, volutes, inlet and output sections. To achieve the required flow characteristics of an average flow rate of 5 l/min and different pressure heads (left - 100mmHg and right - 20mmHg), the impellers were set at different rotating speeds. From the CFD results, a six-blade impeller design was adopted for the development of the BVAD. It was also observed that the fluid can flow smoothly through the pump with minimum shear stress and area of stagnation which are related to haemolysis and thrombosis. Based on the compatible Reynolds number the flow through the model was calculated for the left and the right pumps. As it was not possible to have both the left and right chambers in the experimental model, the left and right pumps were tested separately.

• Bulletin of the Korean Chemical Society
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• 제24권2호
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• pp.197-204
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• 2003

The intracluster ion-molecule reactions of $Ti^+(H_2O)_n,\;Ti^+(CH_3OCH_3)_n,\;and\;Ti^+(CH_3OD)_n$ complexes produced by the mixing of the laser-vaporized plasma and the pulsed supersonic beam were studied using a reflectron time-of-flight mass spectrometer. The reactions of $Ti^+$ with water clusters were dominated by the dehydrogenation reaction, which produces $TiO^+(H_2O)_n$ clusters. The mass spectra resulting from the reactions of $Ti^+\;with\;CH_3OCH_3$ clusters exhibit a major sequence of $Ti^+(OCH_3)_m(CH_3OCH_3)_n$ cluster ions, which is attributed to the insertion of $Ti^+$ ion into C-O bond of $CH_3OCH_3$ followed by $CH_3$ elimination. The prevalence of $Ti^+(OCH_3)_m(CH_3OD)_n$ ions in the reaction of $Ti^+\;with\;CH_3OD$ clusters suggests that D elimination via O-D bond insertion is the preferred decomposition pathway. In addition, the results indicate that consecutive insertion reactions by the $Ti^+$ ion occur for up to three precursor molecules. Thus, examination of $Ti^+$ insertion into three different molecules establishes the reactivity order: O-H > C-O > C-H. The experiments additionally show that the chemical reactivity of heterocluster ions is greatly influenced by cluster size and argon stagnation pressure. The reaction energetics and formation mechanisms of the observed heterocluster ions are also discussed.

• 대한한방내과학회지
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• 제34권2호
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• pp.122-133
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• 2013

Objectives : Burning mouth syndrome (BMS) is characterized by chronic pain or a burning sensation in the mouth. There is limited evidence available to provide clear guidelines for treating BMS patients and a variety of different treatments have been used. This study was designed to investigate the Effects of Korean medicine therapies on oral pain in patients with BMS. Methods : We surveyed 30 BMS patients who newly visited the Oral Diseases Clinic in the Kyung Hee University Korean Medicine Hospital from February 2012 to March 2013. When the patients visited the clinic for the first time, they were evaluated on sociodemographic characteristics, BMS questionnaire, severity of pain using visual analogue scale (VAS) and pressure pain threshold (PPT) of the acupuncture point CV17. After 3 weeks of Korean medicine therapies (acupuncture, electroacupuncture, pharmacopuncture and herbal medicine), they were re-evaluated with the VAS and the PPT. Results : After 3 weeks of Korean medicine therapies, 30 patients' oral pain improved and the PPT score on CV17 rose, which means decrease of qi-stagnation score. Conclusions : Korean medicine therapies were effective on oral pain in patients with BMS. To confirm the additional curative effect and evaluate the efficacy of each treatment, well-designed randomized controlled trials will be needed in the future.

• 항공우주기술
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• 제11권1호
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• pp.68-77
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• 2012

공기를 이용한 축소형 4 노즐 클러스터드 엔진 저부 유동에 대한 CFD 해석을 수행하여 수치 방법에 대한 비교와 저부 유동을 분석하였다. 해석결과 Roe나 AUSM의 공간 차분법에 따른 차이는 없었으며, Spalart-Allmaras 1 방정식 난류 모델이 SST k-${\omega}$ 모델이나 k-${\varepsilon}$ 모델에 비하여 본 연구에 비교적 적합한 것으로 나타났다. 클러스터드 엔진 저부 영역은 팽창된 노즐 플룸이 서로 만나면서 고압의 정체 영역을 일부 형성하며, 일부의 플룸이 저부 방향으로 역류 팽창하는 것이 관측된다. 저부로 팽창된 플룸은 노즐과 노즐 사이의 최소 공간으로 정의되는 "최소 배출면"을 통해 외기로 빠져 나가는 데 저부면에 가까울수록 더욱 빠른 속도로 빠져나가고 경험적 이론과 다르게 노즐과 노즐 사이의 공간 전체가 유동의 목을 형성하는 것이 아닌 것으로 확인된다. 또한 노즐 벽면 온도가 역류 플룸의 온도에 큰 영향을 끼치는 것을 확인하였다.

• 한국전산유체공학회지
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• 제14권1호
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• pp.1-8
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• 2009

To control the coating thickness of zinc in the process of continuous hot-dip galvanizing, it is known from early days that the gas wiping through an air knife system is the most effective because of the obtainable of uniformity of coating thickness, possibility of thin coating, working ability in high speed and simplicity of control. But, the gas wiping using in the galvanizing process brings about a problem of splashing from the strip edge for a certain high speed of coating. Also, it is known that the problem of splashing directly depends upon the galvanizing speed and nozzle stagnation pressure. In theses connections, in the present study, we proposed two kinds of air knife systems having the same expansion rate of nozzle, and the jet structures and coating thicknesses from a conventional and new proposed nozzles are compared. In numerical analysis, the governing equations consisted of two-dimensional time dependent Navier-Stokes equations, standard k-e turbulence model to solve turbulence stress and so on are employed. As a result, it is found that it had better to use the constant rate nozzle from the point view of the energy saving to obtain the same coating thickness. Also, to enhance the cutting ability at the strip, it is advisable to use an air knife with the constant expansion rate nozzle.

• 한국항공우주학회지
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• 제30권6호
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• pp.61-68
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• 2002

초음속 유동장 내 수소 연료의 이중 분사가 갖는 연소 특성에 대한 수치연구를 수행하였다. 연료 이중 분사 유동 구조를 수치적으로 모사하기 비평형 화학반응을 포함한 3차원 Navier-Stokes 방정식과 k-$\omega$ SST난류 모델을 사용하였다. 이중 분사기 사이의 변화에 따른 연소특성의 변화를 이해하기 위해서 파라메터 연구를 수행하였다. 이중 수직분사의 연소특성은 단일 수직분사의 연소특성과 상당히 다른 양상을 보이는 것으로 나타났다. 이중 분사에서 두 분사유동의 연소특성은 서로 다른 것으로 나타났는데, 후방 분사류의 연소 특성은 전방 분사류의 유동 및 연소특성에 크게 영향을 받는 것으로 밝혀졌다. 분사기 사이의 거리가 어떤 특정 거리가 되기 전까지 증가할수록 연소율이 증가하는 것으로 나타났다. 하지만, 그 이후에는 연소율의 증가가 관찰되지 않았으며 오히려 정체압력의 감소가 커져서 전체적인 연소특성은 악화되는 것으로 나타났다. 이는 최적의 연소특성을 위한 두 분사기 사이의 거리가 존재함을 의미하는 것으로 판단된다.

• 한국항공우주학회지
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• 제33권4호
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• pp.79-84
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• 2005

평판 표면에 충돌하는 축대칭, 과소팽창 제트에 대한 실험적 연구가 수행되어졌으며, 벽압력 및 단열 벽온도 분포가 자세히 측정되어졌다. 벽온도 분포 결과에 대한 설명을 위하여 자유제트 내에서의 전온도 값을 전온도 탐침을 사용하여 측정하였다. 본 연구에서 실험 변수로는 과소팽창비와 노즐-평판간 거리가 고려되었다. 노즐-평판 간 거리에 따라 제트 경계 및 충돌면에서의 에너지 박리에 의해 서로 다른 형태의 단열 벽온도 분포가 나타났으며, 과소팽창비가 큰 경우, 중심영역에서의 저온 유체 입자의 고립효과로 정체점의 회복계수가 크게 낮아지는 현상 또한 관찰되었다.

• 대한조선학회지
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• 제26권3호
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• pp.41-50
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• 1989

2차원 날개 단면 주위 유동문제를 포텐셜장에서의 표면양력판이론에 의하여 해석하였고 수치해석 효율을 증대시키기 위한 방법을 제시하였다. 날개 뒷날에서 유동이 쐐기 주위의 유동과 유사하다는 특성을 이용하여 계산효율을 증대시키기 위한 쐐기형 쿠타 조건(wedge type Kutta condition)을 제시하였다. 또한 쐐기형 계산효율을 증대시키기 위하여 세부 분할 방법을 적용하였다. 즉 날개 뒷날 부근의 4개의 양력판을 세분하고 세분된 양력판에서의 다이폴세기는 쐐기 주위 유동특성을 따르게 하였다. 세부분할 방법에 의한 쐐기형 쿠타조건을 2차원 날개단면 문제에 적용하였을 경우 수치계산 효율이 증가됨이 보였다. 날개 앞날에서의 유동은 앞날 반경(leading edge radius)을 갖는 원에 접하는 포물선(osculating parabola) 주위의 유동과 유사하다는 특성을 이용하여 비교적 적은 양력판 갯수에 의한 계산결과로부터 날개 앞날 주위의 유동을 정확히 계산하였다. 날개 앞날 주위의 급격한 유동변화를 정확히 계산함으로써 캐비테이션 발생 문제 및 날개 주위 경계층 문제를 계산하기 위한 정도 높은 입력자료를 제공할 수 있게 되었다.

• 동의생리병리학회지
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• 제29권1호
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• pp.1-10
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• 2015

This article is a study on palpitation of which disease cause, disease mechanism and formulas were analyzed with reference to annotations on "Shanghanlun" and "Jinkuiyaolue". And the scope of modern diseases related with palpitation was drawn by research on clinical papers. The source books are "Zhujieshanghanlun" and "Jinkuiyaoluefanglun" and the clinical papers are searched in China Academic Journals(CAJ) of China National Knowledge Infrastructure(CNKI). 13 clauses in "Shanghanlun" and 9 clauses in "Jinkuiyaolue" and 12 formulas are related with palpitation. Disease mechanisms of palpitation were classified as yang deficiency, yin deficiency, qi deficiency, blood deficiency, retained fluid, cold, etc and these days, qi stagnation, phlegm turbidity, blood stasis and fire heat are also considered as disease mechanisms. Modern diseases related with palpitation are arrhythmia(extrasystole, atrial fibrillation, bradycardia, tachycardia, sick sinus syndrome, atrioventricular block), vascular diseases(arterial occlusion, phlebothrombosis, Buerger's disease, coronary artery disease, vasculitis), blood pressure disorder(hypertension, hypotension) and heart diseases such as heart failure, angina pectoris, myocardial infarction, myocarditis, cardiomyopathy, pericardial effusion. And diseases related with psychological change(cardiac neurosis, anxiety neurosis, neurosis, depression, hyperthyroidism, hypothyroidism), pyrexia, anemia, drug intoxication, etc are also related with palpitation. Zhen Wu Tang showing an efficacy in dilating blood vessels and strengthening cardiac function, Wuling Powder with diuretic effect and Fried Glycyrrhizae Decoction acting on the ${\beta}$ receptor are applied to heart failure in different ways. Fried Glycyrrhizae Decoction(308 cases), Zhen Wu Tang(154), Wuling Powder(54), Xiao Chaihu Tang(34), Sini San(20) are reported to have been clinically applied to cardiovascular diseases and Zhen Wu Tang and Wuling Powder mainly applied to heart failure, Fried Glycyrrhizae Decoction, Lizhong Wan, Sini San and Zhen Wu Tang chiefly applied to arrhythmia related diseases. This study focuses on the general research and consideration on clinical applications and is a preliminary study to understand relations between Korean Medicine's symptoms and categories of modern diseases.