• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.245-250
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• 2003

Hull form development and Anti-rolling tank of G/T 360ton class fishery patrol ship was carried out in the CWC at Chosun university, cooperatively with WJFEL(The West Japan Fluid Engineering Laboratory). Same size of 15 knots class fishery patrol ship was selected as a parent form(Model number: CU-015), and modified fore and after body hull form under the slightly lengthened to be suitable for the operation at 20 knots. This paper investigated for a rolling performance and an effective using method when fishery patrol ship was equipped with anti-rolling tank. On several occasions of rolling test was made reference to design data of a similar ship. Although the hull form was highly constrained in being limited to modification of a parent hull form, significant wave resistance improvement was made.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.613-619
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• 2011

Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers.

• 한국식품영양학회지
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• 제12권3호
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• pp.320-327
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• 1999

The flavonoids are one of the most numberous and widespread groups of natural consituents. The low molecular weight of benzo-${\gamma}$-pyrone derivative are ubiquitous in plants and are vegetables nuts, seeds, leaves, flowers, and bark. The flavonoids constitute of a large class of compounds ubiquitous in plants containing a number of phenolic hydroxyl groups attached to ring structures conferring the antioxidant activity. Epidemiologic studies suggest that the dietary intake of antioxidants constitutes a risk factor for vasclar disease indicating that oxidation may be important in the pathogenesis of human athero-sclerosis. Elevated plasma low density lipoprotein (LDL) cholesterol concentration are associated with accelerated atherosclerosis, LDL is oxidized by smooth muscle cells resulting in several chemicals and physical changes of LDL. Oxidized LDL is responsible for cholesterol loading of macrophages foam cells formation and atherogenesis. There have been insulficient tests of the protective effects of flavonoids against LDL oxidation to make definitive statements about their structure activity relationships. How-ever hydroxylation of the flavone uncleas can appears to be advantageous because polyhydroxylated aglycone flavonoids are potent inhibitor of LDL modification. This identification may lead to new and more effective antioxidant strategies for abrogating the atherosclerotic process the leading cause of death and disability in industrialized societies.

• 한국해양공학회지
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• 제22권2호
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• pp.78-84
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• 2008

As a preliminary step to build a complete superyacht hull design program, the development of superyacht profile design system is introduced. The two-dimensional hull profile is decomposed into four local zones depending upon the functionality and connecting continuity of the profile. Characteristics of each zone are investigated and used to generate the model describing the geometric shape of zone using freeform curves. A set of design parameters is derived from the established geometric model. Generation and modification of a model are is by manipulating the chosen parameters. Four zones designed are integrated to form a final profile. An interactive design system performing all the modeling and modification processes is implemented using the graphic user interface system based an Microsoft Foundation Class and OpenCASCADE, a open graphic library. The shapes of the profiles generated by the developed design system are verified with those of built superyachts. The developed design system will be used for the construction of three-dimensional superyacht hull modeling system.

• 한국수학교육학회지시리즈A:수학교육
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• 제58권4호
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• pp.545-566
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• 2019

본 연구에서는 연구공동체 활동이 개념 지도와 수학적 창의성에 관한 교사 전문성에 어떤 변화를 가져오는지 살펴본다. 연구 결과, 연구공동체 활동은 교사가 개념 지도와 수학적 창의성 촉진 모두에 의미 있는 개선을 시도하는 데 기여한 것으로 나타났다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.313-317
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• 2005

The facility improvement for hot firing test of combustion chamber having thrust of 30-tonf class and chamber pressure of 60bara were performed at ReTF in KARI. The KSR-III main engine having combustion pressure of 13bara and thrust of 12.5tonf had been successfully tested in this facility. To increase the capability of the facility, the feeding and the trust measurement system have been modified. The modification of the feeding system plays also a role of ensuring the stability of propellant supply and two step ignition sequence of combustion chamber. The one-axis thrust measurement system of up to 60tons has been newly manufactured and installed in test stand and the water/kerosene supply lines with high pressure vessel of $4m^3$ and gas nitrogen vessel of $10m^3$ have been designed for regenerative cooling system. The results of cold flow test show that this facility has been successfully improved to satisfy the requirement for hot firing test of high performance combustor.

• Spatial Information Research
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• 제10권3호
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• pp.421-438
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• 2002

GIS을 활용하는 다양한 응용분야에서 공간데이터베이스의 상세한 정도(추상화 수준)는 그 목적에 따라 달라진다. 추상화 수준이 달라지면 공간자료의 기하학적인 단순화뿐 아니라, 객체(인스턴스), 공간 및 속성 자료, 위상관계, 의미관계 등이 변화되거나 유지되어야 한다. 이와 관련하여 본 연구에서는 원시 공간데이터베이스를 추상화하여 목표데이터베이스를 생성하는 방법을 제시하였다. 공간데이터베이스를 추상화하는 연산자를 재정의하고, 어떤 객체에 어떤 연산자들을 어떤 순서로 적용하여야 하는지에 대한 기준을 제시하고, 이 기준에 따라 워크플로우를 제시하였으며, 프로토타입시스템을 개발하여 타당성을 검토했다.

• 대한조선학회논문집
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• 제34권4호
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• pp.72-83
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• 1997

본 연구에서는 연안 및 운하, 두 곳 모두에서 운항이 가능한 컨테이너선에 대한 선형설계를 수행하였다. 설계된 선형은 기존의 140TEU 컨테이너선을 기준선으로 하여 설계된 200TEU급 컨테이너 선형으로, 선수부에 대하여는 기존의 저항시험 자료들을 통한 선형의 재설계도 시도되었다. 모형시험은 선형시험수조에서 일반적인 저항시험을 통한 전저항, 침하와 트림(trim)이 제측되었으며, 선체주위 유동장의 해석을 위한 수치해석으로는 무한수심 뿐만 아니라 제한수로상태에 대하여도 MAC법을 기초로 한 유한차분법(Finite-Difference Method)에 의해 계산이 수행되었다. 이러한 일련의 모형시험 및 유동장의 수치해석을 통하여 설계된 선형의 저항 특성을 파악하였다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 춘계학술대회 학술발표 논문집
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• pp.249-255
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• 2000

HRIV(Hybrid Rule-Interval Variation) method is presented to stabilize a class of nonlinear systems, where SMC(Sliding Mode Control) and ADC (ADaptive Control) schemes are incorporated to overcome the unstable characteristics of a conventional FLC(Fuzzy Logic Control). HRIV method consists of two modes: I-mode (Integral Sliding Mode PLC) and R-mode(RIV method). In I-mode, SMC is used to compensate for MAE(Minimum Approximation Error) caused by the heuristic characteristics of FLC. In R-mode, RIV method reduces interval lengths of rules as states converge to an equilibrium point, which makes the defined Lyapunov function candidate negative semi-definite without considering MAE, and the new uncertain parameters generated in R-mode are compensated by SMC. In RIV method, the overcontraction problem that the states are out of a rule-table can happen by the excessive reduction of rule intervals, which is solved with a dynamic modification of rule-intervals and a transition to I-mode. Especially, HRIV method has advantages to use the analytic upper bound of MAE and to reduce Its effect in the control input, compared with the previous researches. Finally, the proposed method is applied to stabilize a simple nonlinear system and a modified inverted pendulum system in simulation experiments.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.296-303
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• 1998

The purpose of this study was to assess the effects of cavity designs on the marginal leakage of class 5 glass ionomer restorations. The five cavity designs were as follows ; notch shape(A group), notch shape with groove(B group), combined lesion(C group), combined lesion with groove and deep chamfer margin(D group) and combined lesion with groove and shoulder(E group), and each design had 10 cavities. After the cavities were restored with GIC, they were immersed in 0.5% basic fuchsin solution for 6 hours. The specimens were washed thoroughly and sectioned longitudinally in a buccolingual direction through the center of the restorations. The degree of marginal leakage was measured as the extent of dye penetration under the stereoscope. The results of this study were as follows 1. The enamel margins of all groups showed lesser leakage than dentin/cementum margins(p<0.05). 2. The combined lesion(C group) showed more leakage than notch shape(A group), but there was no siginificant difference(p>0.05). 3. In the notch shape, there was no influence on the marginal leakage by the groove preparation. 4. In the combined lesion, marginal leakage was decreased by the groove preparation and marginal modification.