• 한국전산유체공학회지
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• 제15권1호
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• pp.81-87
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• 2010

In this study, we conducted resistance and propulsion performance test of ship composed of the Resistance Test, Propeller Open Water Test and Self Propulsion Test using the CFD(Computational Fluid Dynamics). We used commercial RANS(Reynolds Averaged Navier Stokes equation) solver, as a calculating tool. The unstructured grids were used in a bow and stern of ship, having complex shape, for a convenience of generating grids, and the structured grids were adopted in a central hull and rest of hull having a relatively simple shape which is called hybrid grid method. In addition, The sliding mesh method was adopted to rotate a propeller directly in the Propeller Open Water and Self Propulsion Test. The Resistance Test and Self Propulsion Test were calculated using Volume of Fluid (VOF) model and considering a free surface. And all The three cases were applied realizable k-epsilon model as the turbulence model. The results of calculations were verified for the suitability of calculations by comparing MOERI's EFD results.

• International Journal of Precision Engineering and Manufacturing
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• 제2권2호
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• pp.38-47
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• 2001

This paper decribes the development of computer-aided design of a very precise progressice die for lead frame of semiconductor chip. The approach to the system is based on knowledgr-based rules. Knowledge of fie이 experts. This system has been written in AutoLISP using AutoCAD ona personal computer and the I-DEAS drafting programming Language on the I-DEAS mater series drafting with on HP9000/715(64) workstation. Data exchange between AutoCAD and I-DEAS master series drafting is accomplished using DXF(drawing exchange format) and IGES(initial graphics exchange specification) files. This system is composed of six main modules, which are input and shape treatment, production feasibility check, strip layout, data conversion, die layout, and post processing modules. Based on Knowledge-based rules, the system considers several factors, such as V-notches, dimple, pad chamfer, spank, cavity punch, camber, coined area, cross bow, material and thickness of product, complexities of blank geometry and punch profiles, specifications of available presses, and the availability of standard parts. As forming processes and the die design system using 2D geometry recognition are integrated with the technology of process planning, die design, and CAE analysis, the standardization of die part for lead frames requiting a high precision process is possible. The die layout drawing generated by the die layout module s displayed in graphic form. The developed system makes it possible to design and manufacture lead frame of a semiconductor more efficiently.

• 대한조선학회논문집
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• 제31권3호
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• pp.31-37
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• 1994

선체 형상을 표현하기 위하여 Bi-Cubic B-spline이 가장 널리 사용되고 있다. B-spline곡선 곡면 정의에 있어서 입력 데이터가 불규칙하거나, 주어진 데이터의 갯수가 많은 경우, 또는 형상이 복잡한 경우에 주어진 형상의 부드러운 곡선 곡면(Smooth curves or surfaces)을 재현할 수 있는 역행렬을 구하기 어렵다. 이러한 문제점을 극복하기 위해 새로운 버텍스 산출법(ISE 방법: Image Surface Expansion Method)을 제시한다. 곡선정의를 이용하여 ISE방법을 검증하였고, 수렴성을 확인하였다. 또한 선체형상을 정의하였으며, Open Uniform B-spline으로 형성된 곡면과 비교하였고, ISE방법의 신뢰도를 검증하였다.

• 대한구순구개열학회지
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• 제10권2호
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• pp.67-74
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• 2007

After Tennison introduced a triangular flap method which, for the first time, preserved the Cupid's bow, Randall gave this method a sound mathematical basis. This method is also called as an inferior triangular cheiloplasty which is characterized by making a small triangular flap from the lateral border of cleft destined to be fitted into an incision on the medial side of cleft. He postulated that the height obtained was equal to the sum of the median of the two triangles used in the cheiloplasty. Using this technique, a 22 month-old male patient with incomplete unilateral cleft lip was corrected primarily. The deviation of the columella and flattening of the nostril on the cleft side were minimal. The operation was done under general anesthesia and patient was healed uneventfully. We tried to improve the symmetry and esthetic feature of philtrum, nostril sill, alar-facial groove, preventing the notch formation on the nostril floor, and to reconstruct the muscle sling in the upper part of lip. The shape of Cupid's bow was restored, and the symmetry of columella was regained as a result. In summary, the inferior triangular cheiloplasty is effective to correct the primary unilateral cleft lip, results in the restoration of favorable anatomy and function.

• 천문학회보
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• 제43권1호
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• pp.65.2-65.2
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• 2018

Through MIRIS $Pa{\alpha}$ Galactic plane survey, a lot of $Pa{\alpha}$ blobs were detected along the plane. To reveal their characteristics, we are planning to collect NIR high-resolution spectroscopic data for them by using Immersion GRating INfrared Spectrograph (IGRINS). Here, we present the preliminary results of the IGRINS observations for a Herbig Be star, MWC 1080, which is one of the $Pa{\alpha}$ blobs detected in Cepheus. This Herbig Be star is known to possess a lot of young stellar objects (YSOs) and bright MIR ($10-20{\mu}m$) nebulosity in its vicinity. From IPHAS $H{\alpha}$ data, we revealed large extended $H{\alpha}$ features that correlate well with MIR and 13CO morphologies around MWC 1080. A part of the $H{\alpha}$ features shows a bow shock shape to the northeast of the primary star MWC 1080A, which seems to be due to an outflow from MWC 1080A. Through IGRINS observations, we detected faint [Fe II] ${\lambda}1.644{\mu}m$ and H2 1-0 S(1) ${\lambda}2.122{\mu}m$ emission lines around the bow shock feature. Interestingly, to the east region of MWC 1080A, we also detected strong [Fe II] and H2 emission lines with a couple of velocity components, which suggests the detection of a new outflow from another YSO. Broad $Br{\gamma}$ ${\lambda}2.1662{\mu}m$ line and H2 lines with various velocity components were detected around the bright MIR and $H{\alpha}$ nebulosity as well.

• 한국전자파학회논문지
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• 제17권12호
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• pp.1199-1205
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• 2006

본 논문은 두 개의 대역 저지 반파장 슬롯을 방사체에 삽입하여, 향상된 대역 저지 특성을 갖는 보우타이형 광대역 모노폴 안테나를 제안하였다. 제안된 안테나는 전자기적으로 급전된 보우타이 형태의 방사 평면과 접지면 사이에 반원 모양의 기생 접지면을 추가한 구조이다. 향상된 대역 저지 특성을 얻기 위하여 두 수평 슬롯간의 결합량을 조절하였다. 측정된 안테나는 $4.96{\sim}5.51GHz$에서 저지 특성을 갖고, $2.7{\sim}6.9GHz$에서 정재파비 2.0 이하를 만족하는 광대역 특성을 나타내었다. 단일 슬롯 사용과 비교하면, 넓은 저지 대역폭과 향상된 스커트 특성을 나타내었다. 측정된 안테나의 방사 패턴은 이상적인 모노폴 안테나와 유사한 특성을 가지며, 저지 대역에서의 안테나 이득은 다른 동작 주파수에 비해 x-z 평면을 기준으로 $5{\sim}10dB$ 이상 감소되었다.

• 수산해양기술연구
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• 제53권4호
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• pp.446-455
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• 2017

The improvement of resistance performance for the 4.99 ton class fishing boats was shown. The 4.99 ton fishing boats are the most commonly used one in the Korean coastal region. The evaluation of resistance performance was estimated by the Computational Fluid Dynamics (CFD) analysis. The CFD simulation was performed by the validation for various types of bow shapes on the hull. The optimized hull form from the simulation was selected and showed the best resistance performance. This hull type was tested on the towing tank in the National Institute of Fisheries Science (NIFS). The effective horsepower (EHP) was estimated by the resistance test on the towing tank with the bare hull condition. The drag force on the three service speed conditions was obtained for the resistance analysis to power prediction. The measured drag forces are compared with the results from the CFD simulation with one another. As results of the model tests, it was confirmed that the shape of the bow is an important factor in the resistance performance. The effective horsepower decreased about 30% in comparison with the conventional hull form. Also, the resistance performance improved the reduction of required horsepower, which especially contributed to the energy-saving for the fisheries industry. In the CFD analysis, the resistance performance improved slightly. In this case, the ratio of the residual resistance ($C_R$) in the total resistance ($C_T$) was high. Therefore, the CFD analysis was not enough to satisfy with reflection for the free surface and wave form in the CFD procedure. Both model test and CFD calculation in this study can be applied to the initial design process for the coastal fishing vessel.

• 대한조선학회논문집
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• 제44권5호
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• pp.542-550
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• 2007

A geometry modification is one of main keys in achieving a successful optimization. The optimized hull form generated from the geometry modification should be a realistic, faired form from the ship manufacturing point of view. This paper presents a practical hull optimization procedure using a parametric modification function. In the parametric modification function method, the initial ship geometry was easily deformed according to the variations of design parameters. For example, bulbous bow can be modified with several parameters such as bulb area, bulb length, bulb height etc. Design parameters are considered as design variables to modify hull form, which can reduce the number of design variables in optimization process and hence reduce its time cost. To verify the use of the parametric modification function, optimization for KCS was performed at its design speed (FN=0.26) and the wave making resistance is calculated using a well proven potential code with fully nonlinear free surface conditions. The design variables used are key design parameters such as Cp curve, section shape and bulb shape. This study shows that the hull form optimized by the parametric modification function brings 7.6% reduction in wave making resistance. In addition, for verification and comparison purpose, a direct geometry variation method using a bell-shape modification function is used. It is shown that the optimal hull form generated by the bell-shaped modification function is very similar to that produced by the parametric modification function. However, the total running time of the parametric optimization is six times shorter than that of the bell shape modification method, showing the effectiveness and practicalness from a designer point of view in ship yards.

• The International Journal of Costume Culture
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• 제8권2호
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• pp.71-84
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• 2005

Fibulae have been used as clothing fasteners throughout history. They were especially popular with the Celts, but were also used by the Greeks, Romans, Saxons, and Vikings, to name a few. The earliest examples are found in the Mediterranean and Middle East, and date from 800 B. C. and earlier. Their use continues today, in the form of the modern safety pin. The first fibulae of the Bronze Age were very simple, much like modern safety pins. The form of this small functional object varies from simple to extravagant since it is also seen as a piece of jewelry, and is thus subject to the evolution of style. Its size depends on the thick/Jess of the clothing to be attached. Its fabrication demonstrates a great mastery of metal work. Fibulae would vary with the taste and wealth of the wearer. The Fibulae were divided into 10 styles according to the shape, Fibulae with Safety pin shaped style, Penannular shaped style, Animal shaped style, Diamond shaped style, Radiated head shaped style, Horsefly shaped style, Arched bow shaped style, Fan-shaped style, Trumpet shaped style, Arched-fan shaped style.

• 대한조선학회논문집
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• 제47권3호
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• pp.469-475
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• 2010

The operation scenarios, types of ice, draft and propulsion system are important design point on the beginning stage of the ice breaking vessel. The concept of hull form in ice breaking vessel has to compromise the performance according to the operation route especially if ship is operating in ice and ice free water. The several hull forms were proposed to optimize the capability of the vessel in this paper. The effect of hull form according to type of ice is also discussing and explaining the ice resistance in each ice type as like pack ice, brash ice, level ice, rubble ice and ice ridge. The draft effect was examined and propulsion system for example FPP(Fixed pitch propeller), CPP(Controllable pitch propeller) and POD system was compared focusing on the propulsion efficiency.