• 대한조선학회논문집
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• 제49권5호
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• pp.367-375
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• 2012

In this study, hull form of main vessel of Korean large purse seiner fishing industry is developed for the improvement of resistance performance as well as for the satisfaction to the Standard of Fishing Convention, ILO. Through the modification of reference hull form parameters and local characteristics, the hull form development is carried out. The optimum hull form parameters are searched by Sequential Quadratic Programing(SQP) method with the power estimation method of Holtrop & Mannen. To minimize the wave resistance, bulbous bow parameters are determined by the bulbous bow design method of Alvarino. The plasmatic curve is redesigned from that of the reference hull by using Lackenby method. The resistance performances of the reference and designed hull forms are estimated by using numerical simulation method. Also, the judgment of seakeeping ability and the estimation of intact stability for the designed hull form is carried out. As a result, the optimum hull form is proposed. To verify the improvement of resistance performance, model tests are carried out in towing tank. The results show that the resistance of the designed hull form is about 14% smaller than that of the reference hull from at design speed. A new hull form proposed in this study can contribute to the development of the main vessel hull form of Korean large purse seiner fishing system.

• 대한조선학회논문집
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• 제49권5호
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• pp.391-399
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• 2012

This paper presents a method of hull form design for the assistant vessel which is used both as a lighting boat and a fish carrying boat for the fleet of newly formated purse seiner vessels. The optimum hull form parameters are searched by the Sequential Quadratic Programing(SQP) method with the power estimation method of Van Oortmerssen. The prismatic curve is redesigned from that of the reference hull by the Lackenby method. Through the modification of the hull form by using a CAD system, the design procedure is completed. The resistance performances of the reference and the modified hull forms are estimated by using a numerical simulation method. Also, the estimation of seakeeping ability and stability for the modified hull forms are carried out. And then, an optimum hull form is proposed for the designed hull form. Ship model tests for the reference and the designed hull forms are carried out at ship model basin. The results of the experiments show that the effective horse power of the designed hull form is about 22% smaller than that of the reference hull form at design speed. The designed hull form proposed in this study will contribute to the development of the hull form for Korean large purse seiner vessels.

• Macromolecular Research
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• 제11권1호
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• pp.14-18
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• 2003

Grafting of glycidyl methacrylate (GMA) upon coralline hydroxyapatite in conjugation with demineralized bone matrix (CHA-DBM) using equal molar ratio of potassium persulfate/sodium metabisulfite redox initiating system was investigated in aqueous medium. The optimum reaction condition was standardized by varying the concentrations of backbone, monomer, initiator, temperature and time. The results obtained imply that the percent grafting was found to increase initially and then decrease in most of the cases. The optimum temperature and time were found to be 50 $^{\circ}C$ and 180 min, respectively, to obtain higher grafting yield. Fourier transform infrared (FT-IR) spectroscopy and X-ray powder diffraction (XRD) method were employed for the proof of grafting. The FT-IR spectrum of grafted CHA-DBM showed epoxy groups at 905 and 853 $cm^{-1}$ / and ester carbonyl group at 1731 $cm^{-1}$ / of poly(glycidyl methacrylate) (PGMA) in addition to the characteristic absorptions of CHA-DBM, which provides evidence of the grafting. The XRD results clearly indicated that the crystallographic structure of the grafted CHA-DBM has not changed due to the grafting reaction. Further, no phase transformation was detected by the XRD analysis, which suggests that the PGMA is grafted only on the surface of CHA-DBM backbone. The grafted CHA-DBM will have better functionality because of their surface modification and hence they may be more useful in coupling of therapeutic agents through epoxy groups apart from being used as osteogenic material.

• 한국추진공학회지
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• 제26권3호
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• pp.22-31
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• 2022

기존 Finocyl 그레인 형상 설계는 임의의 형상을 가정하고 Burn-back 해석을 통해 요구조건 만족 여부 확인, 형상 수정의 과정을 반복한다. 이와 같은 설계는 작업자의 설계 피로도를 높이고, 역량에 따라 설계 완성도가 상이한 문제를 가지고 있다. 이에 본 연구는 기존 설계의 문제를 해결하기 위해 Burn-back 자동화 해석 프로그램에 유전 알고리즘을 적용한 최적 설계 방법을 개발하였다. 안정적인 탐색을 위해 가변형 Offset, 작도 불능 형상 변수 제어 기법을 개발하고, 중립형 및 이중추력형 면적선도 형상을 설계하여 성능을 검증하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2654-2659
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• 2007

Fluid flow and temperature distribution inside a molten zinc bath were investigated by computational fluid dynamics method. Modeling the channel inductor where alternating current of 60Hz was applied, Lorentz force and generated heat were obtained and later supplemented as source terms to momentum and heat equations. The present work validates CFD technique is effectively adopted when the inductor hardware modification or its configuration is considered for the optimum flows.

• 대한교통학회지
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• 제13권1호
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• pp.95-110
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• 1995

n this research neural -based model was developed to forecast link travel times , And it is also compared wiht other time series forecasting models such as Box-Jenkins model, Kalman filter model. These models are validated to evaluate the accuracy of models with real time series data gathered by the license plate method. Neural network's convergency and generalization were investigated by modifying learning rate, momentum term and the number of hidden layer units. Through this experiment, the optimum configuration of the nerual network architecture was determined. Optimumlearining rate, momentum term and the number of hidden layer units hsow 0.3, 0.5, 13 respectively. It may be applied to DRGS(dynamic route guidance system) with a minor modification. The methods are suggested at the condlusion of this paper, And there is no doubt that this neural -based model can be applied to many other itme series forecating problem such as populationforecasting vehicel volume forecasting et .

• 한국의류학회지
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• 제33권7호
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• pp.1121-1127
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• 2009

This study presents an eco-friendly and one-step finishing method for modifying fiber property that reduces fiber damage in wool/polyester blend fabrics. Lipase from aspergillus oryzae is used in this experiment. The enzymatic treatment condition is optimized by measuring the relative activity of lipase depending on pH level, temperature, concentration of lipase, and treatment time. The concentration of $CaCl_2$as an activator is determined by the characteristics including whiteness, water contact angle (WCA), and dyeing property. The modified properties of lipase treated fabrics are tested for pill resistance and surface morphology. The results are described as follows: the optimum condions for lipase treatment constitute a pH level of 8.0, treatment temperature of 40$^{\circ}$$_C$, concentration of lipase at 100% (o.w.f), and a treatment time of 90 minutes. $CaCl_2$helps in raising lipase activation, and the optimum concentration is 50mM. The whiteness, wet ability, and pill resistance of lipase treated fabrics improves as compared to the control. The dyeing property of lipase treated fabrics improved by 53.5% after using the one-bath dyeing method. This means that lipase treatment can save time and cost during the dyeing process since lipase treatment modifies wool and polyester fibers. The surface of lipase treated wool fibers do not exhibit any change, however voids and cracks manifest on the surface of lipase treated polyester fibers.

• 대한화학회지
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• 제40권2호
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• pp.109-116
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• 1996

물시료 중 존재하는 흔적량 게르마늄을 전열 원자흡수 분광광도법으로 정랑하기 위해 사용되는 매트릭스 개선제의 종류와 사용량, 이에 따를 회화 및 원자화 온도의 변화, 보조제의 사용여부 및 양에 관하여 연구하였다. 게르마늄은 회화단계에서 이산화 게르마늄이 흑연로 성분인 탄소로 인해 휘발성 일산화 게르마늄으로 환원되에 감도 및 재현성을 저하시킨다. 따라서 개선제를 사용하여 게르마늄을 열적 및 화학적으로 안정화시켜야 한다. 이를 위해 단일 개선제를 사용할 경우 파라듐이 가장 좋은 효과를 나타내었다. 이 경우 원자화온도는 변화시키지 않지만, 회화온도는 800.deg.C에서 1, 000.deg.C로 올릴수 있었고 흡광도도 증가하였다. 이런 조건에서 팔라듐의 농도가 게르마늄에 대해 몰비로 14-100인 10-70.mu.g/mL까지 흡광도가 일정하였다. 보조개선제의 사용도 검토하였는데, 1% 수산화암모늄을 가하여 회화온도를 1, 000.deg.C까지 증가시켰다. 이제까지 검토한 최적조건을 바탕으로 광천수 3가지를 분석한 결과 게르마늄이 2.46, 1.60 및 0.020.mu./mL이었다. 끝으로, 시료에 일정량의 게르마늄을 첨가하여 얻은 회수율은 모두 95%이상으로 정량적이라고 할 수 있고, 검출한계는 6.9ng/mL로 흔적량 게르마늄 분석에 유용한 것으로 판단되었다.

• 접착 및 계면
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• 제10권3호
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• pp.148-153
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• 2009

용제 및 수용성 접착제를 도포한 몇가지 고분자 소재에 평판형 플라즈마 반응기로 플라즈마 전처리 방식을 이용하여 소재표면의 접착력을 향상 시켰다. 분위기 기류를 질소로 하고 유량을 30~100 mL/min, 반응시간은 0~30 s로 하여 밀도를 변화시킨 PU 소재를 주 물질로 하여 EVA foam, Leather (Action), Rubber 소재에 대하여 각 조건별로 플라즈마 처리시켜 처리 전후의 각 소재별 접촉각과 접착박리강도 측정을 통한 각소재의 접착력 변화와, SEM분석을 이용한 처리 전후의 표면 변화를 측정하여 플라즈마 처리의 영향과 효과를 산출하였다. 대기압 평판형 플라즈마 반응기를 이용하여 최적 조건인 기체유량 100 ml/min, 전처리시간 10 s에서 PU foam, EVA form, Leather (Action) 및 Rubber 소재의 접착력 향상을 확인하였다.

• Composites Research
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• 제23권6호
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• pp.32-38
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• 2010

폴리아미드 직물과 NBR의 최적 접착특성을 나타낼 수 있는 조건을 검토하기 위해 대기압 플라즈마(APP) 처리 효과에 대한 실험적 연구를 하였다. 대기압 화염 플라즈마(APFP) 처리의 경우 주어진 계면조건에서 최적의 처리횟수는 2회였다. APFP 처리 횟수가 증가함에 따라 직물의 열변형은 더욱 심하였다. APFP 처리 직물을 강화한 복합재료의 접착강도는 접착제를 한번 혹은 두번 도포한 계면에 대해 플라즈마를 처리하지 않은 경우에 비해 약 35% 증가하였다. 접착제를 중복 도포하였을 때, APFP 처리 직물 강화한 복합재료의 접착에너지는 약 4배 증가하였다. APFP 처리에 의한 폴리아미드 직물의 표면 개질이 다른 형태의 APP 처리방식과 비교했을 때, 경제적이고 빠르며 고무와의 접착강도를 개선시킬 수 있는 방법이라고 판단된다.