• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1632-1639
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• 2004

Numerical calculation has been performed to investigate the transport phenomena in the horizontal reactor which has two different gas inlets for MOCVD(metalorganic chemical vapor deposition). The full elliptic governing equations for continuity, momentum, energy and chemical species are solved by using the commercial code FLUENT. It is investigated how thermal characteristics, reactor geometry, and the operating parameters affect flow fields, mass fraction of each reactants. The numerical simulations demonstrate that flow rate of each species, inlet geometry of the reactor, and its distance from the susceptor as well as the inclination of upper wall of reactor can be used effectively to optimize reactor performance. The commonly used idealized boundary conditions are also investigated to predict flow phenomena in the actual deposition system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.12
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• pp.1683-1691
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• 2000

In this study, it is numerically revealed that the secondary flow due to the Coriolls force in a straight duct rotating about an axis perpendicular to that of the duct is analogous to that caused by the centrifugal force in a stationary curved duct. Dimensionless parameters $K_{LR}=Re/\sqrt{Ro}$ and Rossby number in a rotating straight duct were used as a set corresponding to Dean number and curvature ratio in a stationary curved duct. When the value of Rossby number and curvature ratio is large, it is shown that the flow field satisfies the `asymptotic invariance property`, that is, there are strong quantitative similarities between the two flows such as friction factors, flow patterns, and maximum axial velocity magnitudes for the same values of $K_{LR}$ and Dean number.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.688-692
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• 2010

Wireless sensor network system collects and analyzes real-time data that have been requested by the many application nodes. This paper has constructed a sensor network cluster with various elements in the Gunsan City area of Jeollabuk-do, S.korea. The purpose of this paper is to utilize the constructed system in order to illustrate the real-time data in a diagram and analyze it to deduce the change ratio. The resulting analysis contents allow simple data interpretation by illustrating the data in change ratio by time, space, and motional directions. This analytical method will offer great benefit to those users using the wireless sensor network.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.225-233
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• 2007

The growth of GaN on the patterned substances has proven favorable to achieve thick, crack-free GaN layers. In this paper, numerical modeling of transport and reaction of species is performed to estimate the growth rate of GaN from tile reaction of TMG(trimethly-gallium) and ammonia. GaN growth rate was estimated through the model analysis including the effect of species velocity, thermal convection and chemical reaction, and thermal condition for the uniform deposition was to be presented. The effect of shape and construction of microscopic pattern was also investigated using a simulator to perform surface analysis, and a review was done on the quantitative thickness and shape in making GaN layer on the pattern. Quantitative analysis was especially performed about the shape of reactor geometry, periodicity of pattern and flow conditions which decisively affect the quality of crystal growth. It was found that the conformal deposition could be obtained with the inclination of trench ${\Theta}>125^{\circ}$. The aspect ratio was sensitive to the void formation inside trench and the void located deep in trench with increased aspect ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.113-120
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• 2013

This paper proposes a design optimization approach for core of solenoid actuators by combining optimization techniques with the finite element method (FEM). A solenoid is an important element part which hydraulically controls a transmission system, etc. The demanded feature of the solenoid is that it performs an electromagnetic force output being constant regardless of the stroke and being proportional to coil current. The plunger compresses a spring with a minimum force of 12 N over an 1.7 mm travel. The orthogonal array, analysis of variance (ANOVA) techniques and response surface optimization, are employed to determine the main effects and their optimal design variables. The methodology is demonstrated as a optimization tool for the core design of a solenoid actuator.

• Archives of Pharmacal Research
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• v.25 no.5
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• pp.628-635
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• 2002

Five terpenes (1~5), three fatty acids (6~8), two sterols (9 and 11), and a monogalactosyldiacyl glycerol (10) were isolated from the methylene chloride extract of the aerial part of Cirsium setidens. Their chemical structures were determined to be $\alpha$-tocopherol (1), 25-hydroperoxycycloart-23-en-3$\beta$-o1 (2), 24-hydroperoxycycloart-25-en-3$\beta$-o1 (3), mokko lactone (4), transphytol (5), 9, 12, 15-octadecatrienoic acid (6), 9, 12-octadecadienoic acid (7), hexadecanoic acid (8), acylglycosyl $\beta$-sitosterol (9), (2R)-1, 2-O-(9z, 12z, 15z-dioctadecatrienoyl)-3-O-$\beta$-D-galactopyranosyl glycerol (10) and $\beta$-sitosterol glucoside (11) by spectral evidences. Compound 3 exhibited significant cytotoxic activity against five human cancer cell lines with its $ED_{50}$ values ranging from 2.66 to 11.25 $\mu$M.

• 연구논문집
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• s.28
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• pp.219-227
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• 1998

In order to investigate the interfacial structure between TiN and iron nitride, an AISI 4140 steel was nitrided to form a layer of thickness 15$\mum$ by DC ion nitriding, then the surface was bombarded with Ti ions and subsequently coated a TiN film of 5$\mum$ by arc ion plating method. The interfacial microstructure between TiN and iron nitride was characterized by optical microscope, SEM and XRD. So called black layer was observed in the duplex treatment. It was resulted from the decomposition of iron nitride during the bombardment. Its thickness was increased with increasing bombardment time at high bias voltage. But the thickness was greatly decreased when the iron nitride was bombarded with a nitrogen gas or at a reduced bias voltage. The adhesion strength of the top TiN coating was decreased with increasing thickness of the black layer. Furthermore, the reduced adhesion strength in this system was discussed in view of the interfacial structural relationship between TiN and iron nitride.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.415-417
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• 2013

바다는 자원의 보고로서 많은 수산업 활동을 통환 경재활동이 활발히 이루어 지고 있으나 기상 등의 해양환경에 많은 영향을 받고 있다. 이 때문에 자동화된 해양 환경 분석 및 예측 기술에 대한 연구가 활발히 진행 되고 있다. 현재 국내에서 수산업 활동에 영향을 미치는 해양 재해로는 기름 유출에 의한 해양오염의 피해, 적조에 의한 수산업의 피해, 해양환경 이변에 의한 수산업 및 재해 피해 등 이외에 다양한 피해가 있다. 해양 환경 자료의 수집과 수집된 자료를 분석하여서 해양재해를 예측하면 이들의 피해를 최소화하는데 기여할 수 있다. 그러나 국내 해양 환경에 대한 조사 및 분석 연구는 미흡한 편에 있다. 이에 본 논문은 국내의 원해 및 근 해역에서 수집된 해양 환경 자료를 분석하여 해양 재해를 예측할 수 있는 시스템 클라우드 기반의 해양재해 예측 시스템을 연구한다.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.68.4-69
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• 2016

We report preliminary results of KaVA observations of central galaxies in cool-core and non cool-core clusters. The main goal is to study how cooling environments of galaxy clusters affect the central AGN activities especially at its innermost region. For KaVA observations, 7 radio bright AGNs have been selected from the extended Highest Flux Galaxy Cluster Sample (eHIFLUGCS; the X-ray flux limited & all sky galaxy cluster catalog) with various cooling timescales. In our previous KVN study, we have found that most AGNs in the cool-core clusters show the hint of pc-scale jet-like features while the ones in the non cool-core clusters do not. Using the KaVA 22/43 GHz data of a much higher resolution than the KVN resolution, we have investigated detailed pc-scale jet properties such as physical size, morphology, and radiative age. Based on the KaVA data, we discuss the effect of cluster cooling environment on the evolution of AGNs in the cluster center.

• The Journal of Korean Obstetrics and Gynecology
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• v.29 no.1
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• pp.92-101
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• 2016

Objectives: The purpose of this systematic review was to overview and evaluate the effectiveness of fumigation treatment for women with atrophic vaginitis. Methods: We searched articles from Pubmed, Chinese Academic Journals (CAJ) and Oasis online databases. Searching keywords were ‘fumigation’, ‘atrophic vaginitis’, ‘vaginitis’, ‘阴道炎’, ‘膣炎’, ‘老年性 阴道炎’, ‘坐熏’, ‘熏洗’, ‘熏浴’, ‘좌훈요법’, ‘질염’, ‘위축성질염’. After searching the articles, we performed quality assessment using Cochrane risk of bias (RoB) tool. Results: Among the 142 articles were searched, 5 randomized controlled clinical trials (RCTs) were finally selected. All of 5 studies showed that fumigation treatment has significant effect on atrophic vaginitis in terms of the effectiveness rate, but 3 studies were not statistically significant. Conclusions: Our systematic review found encouraging but limited evidence of fumigation therapy for atrophic vaginitis. We recommend clinical trials which obtain stronger evidence without the demerits of trial design.