• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.81-82
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• 2016

본 논문에서는 UWB 대역에서 동작하는 소형 대수-주기 반-보우타이 다이폴 배열 안테나에 대한 설계 방법에 대하여 연구하였다. 제안된 안테나는 일반적인 대수-주기 다이폴 배열 안테나에서 사용되는 스트립 형태의 다이폴 소자 대신에 반-보우타이 형태의 다이폴 소자를 사용하고 소자간의 간격을 줄여 소형화하였다. 반-보우타이 다이폴 소자의 벌어지는 각도와 소자 사이의 간격에 따른 입력반사계수와 이득 특성을 분석하였다. 최적화된 안테나를 FR4 기판에 설계하였고, 전압 정재파비(VSWR; voltage standing wave) < 2인 대역이 3.05-13.96 GHz으로 UWB 대역에서 동작하는 것을 확인하였다.

• 한국해양공학회지
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• 제17권5호
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• pp.88-94
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• 2003

A series of tests of 5 model ships, selected from a data survey of 10 Gross Tonnage actual fishing boats, were performed in two circulating water channels (Chosun University in Korea and WJFEL in Japan), in order to develop the basic hull form of a 25 knots-class fishing boat. Resistance tests, trim and sinkage measurements and wave pattern observations etc., were included in each I1wdel test, and the model test results were compared and analyzed. The result was as follows: P-4 hull form ship changed into Deep V type bow is the best hull form with good performance, especially with regard to ship's resistance efficiency.

• 대한조선학회지
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• 제4권1호
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• pp.1-34
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• 1967

The wave-cancelling effects of a large bulbous bow on the coastal passenger boat have been investigated in deep and shallow water. The following characteristics have been cleared through resistance tests with the model of the Korea standard type coastal passenger vessel(LWL=25.8m, B=5.5m, T=1.65m) equipped with large bulbous bows of various sizes. (1) Over the range of Froude Number 0.30, the wavemaking resistance coefficients decrease 30% or more. (2) The optimum location of bulb center is around 8% L from F.P. (3) On the 120 G.T. passenger coaster which has a speed corresponding to Froude Number 0.34, the most advantageous bulb is the one whose $a_0/L$ is about 0.28. When the speed is up, the bulb radius should be increased accordingly. (4) The large bulbous bows are effective in shallow water to a water depth of H/T=2.0. (5) Tendency to the increase in the resistance of the hull with large bulbous bow in the shallow water is generally smaller than that of the hull without bulb.

• 한국해양공학회지
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• 제26권1호
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• pp.9-16
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• 2012

This paper presents the numerical results of a simulation of the free surface flow around a blunt bow ship model and focuses on the validation of the proposed method with a brief investigation of the relation between the resistance and free surface behavior. A finite volume method based on the Reynolds Averaged Navier-Stokes (RANS) approach is used to solve the governing flow equations, where the free surface, including wave breaking,is captured by using a two-phase Level-Set (LS) method. For turbulence closure, a two equation k-${\varepsilon}$ model with the standard wall function technique is used. Finally, the numerical results are compared with the available experimental data, showing good agreement.

• 수산해양기술연구
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• 제51권4호
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• pp.504-511
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• 2015

In this paper, the results of evaluating the passenger comfort due to the standard deviation of acceleration in vertical and lateral direction regarding the ship response in irregular wave by ordinary strip method in regular wave and energy spectrum using linear superposition theory in order to evaluate the motion of experimental ship are as follows. According to the results of ship response, it was possible to find that, in order to reduce the motion of ship, a ship operating in bow sea was more stable than in quartering sea. In the results of analyzing the standard deviation of acceleration in vertical direction according to each component wave pattern, when there was a wave length of 56m and an average wave period of 6 sec, most of cases showed the peak value. And among them, the standard deviation was 0.35 which was the highest in head sea. And in case of lateral direction, the maximum value was shown in a wave length of 100m and an average wave period of 8 sec. And it was 0.16 in beam sea and ${\chi}=150^{\circ}$. In the evaluation of passenger comfort due to standard acceleration in vertical and lateral direction, it was 80% in head and bow sea. On the other hand, it was shown to be 15% in follow sea. Accordingly, when the expected wave height in a sea area where a training ship was intended to operate was known, it was possible to predict the routing of ship. And altering her course could reduce the passenger comfort by approximately 50%.

• 대한조선학회지
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• 제12권1호
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• pp.37-40
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• 1975

Heave and pitch amplitude and phase lag, relative vertical displacement, velocity and acceralation at bow as bow motion and wave exciting force and moment of a DWT 260,000 ton class tanker in the regular head wave have been calculated. All the calculations have been made by the computer program SD08 of Seoul National University. As the results it is cleared heave amplitude and acceralation have large value in the ballast condition and low Froude-number than full load condition and higher Froude numer as for as the $\frac{\lambda}{L}$ is lower than near around 1.0, however they have quite large values as $\frac{\lambda}{L}$ goes up.

• 수산해양기술연구
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• 제52권4호
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• pp.339-346
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• 2016

The aim of this research was to the experimental data using statistical and spectral analyzing method to get the motion reponses of a stern trawler in operation states such as drifting, sailing and trawling according to the wave height. In drifting, the significant and the maximum valuer of roll in beam sea increased according to the wave height, but those of pitch decreased. The response and the period of peak of roll in beam sea were increased, but those of pitch decreased. In navigation, the significant and maximum values of roll increased remarkably according to the wave height, but those of pitch changed a little. The response of roll was highest in quartering sea, beam sea and then following sea, but those of pitch was highest in bow sea, head sea and then beam sea in the order of all wave heights. The period of peak of roll due to the wave height and the wave direction changed from 3.8 to 9.9 seconds, and those of pitch changed from 3.3 to 10.4 seconds. In trawling, the significant and maximum values of roll increased a little according to the wave height, but those of pitch increased significantly. The response of roll was highest in beam sea, bow sea and then quartering sea, but those of pitch was highest in head sea, following sea, and then beam sea in the order. The period of peak of roll due to the wave height and the direction changed from 6.6 to 10.9 seconds, and those of pitch changed from 6.7 to 11.2 seconds.

• 한국항해학회지
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• 제15권3호
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• pp.73-97
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• 1991

The analysis and investigation are described for White's[2] equations compared to the equations of Runeburg[3] and Milano[5] for continuous icebreaking mode, Tunik[8-1] and Ghoneim[8-2] for ramming icebreaking mode. Calculation results compare reasonably well with published model-scale and full-scale icebreaker data by Baker[1] and Dick[11]. During continuous and ramming mode operation, using characteristics of an incebreaker, down ward force on ice and standard ice thickness broken are predicted. Additionally draft, trim and extraction difficulty are also predicted. The bow part line of an icebreakin $g^{ply}$ vessel is designed aiming to maximize the ice breaking capabiltiy as following conditions-low bow angle[20 degrees] at designed waterline, small spread angle complement [6 degrees] at designed waterline, small spread angle complement [6 degrees] and high propeller thrust [220tons]. with plow, two reamers and wave type bumper.

• 한국항해항만학회지
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• 제34권10호
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• pp.741-746
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• 2010

선박이 파랑중을 항행할 경우에는 정수중에 비하여 저항이 증가하기 때문에 예부선의 안정성 확보를 위해 예선의 예인마력과 예인삭의 절단하중 등을 산정할 때에 부선의 정수중 저항값 및 파랑중 저항값을 정확히 추정해야 안전한 예항업무를 이행할 수 있다. 현재 정부에서 제안하고 있는 방법에 의하면 부선의 전저항 산정시 마찰저항, 조파저항, 공기저항은 선체의 형상 및 예선의 속력 등을 고려하여 산정하지만 부가저항은 유의파고에 따라 일률적으로 적용하고 있다. 본 연구에서는 파랑중 부가저항 추정을 위해 수치계산을 실시하여 wigley 선형에 대한 기존의 실험 데이터와 상호 비교함으로서 본 계산법의 유효성을 검증하고, 검증된 수치계산법을 토대로 실무에서 많이 사용되고 있는 두개의 부선 모델을 대상으로 계산을 실행한 결과 부선의 부가저항은 파도와의 만남각에 따라 약 0.3∼1.1톤, 예인속력에 따라 약 0.4∼1.2톤, 선수형상에 따라 약 0.5∼1.1톤으로 차이가 발생함을 확인하였다.

• 대한조선학회논문집
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• 제36권4호
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• pp.87-94
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• 1999

선수 구조부의 파랑충격현상은 대단히 복잡한 현상을 나타내고 있고 정확하게 규명하기 어렵기 때문에 아직 경험적인 설계에 의존하고 있다. 파랑충격하중에 의한 선수 구조부의 손상은 주로 충격압력역적과 파랑충격하중의 면적에 의하여 크게 영향을 받는다. 본 연구에서는 두 번째 단계로서 파랑충격하중에 대한 선수 구조부 강도의 추정을 위하여 효율적인 부재치수의 결정 프로그램을 개발하고, 파랑충격하중의 면적을 추정하고자 한다. 동적 비선형 범용 프로그램 LS/DYNA3D를 이용하여 DWT 300,000급 VLCC의 선수 구조부를 이상화된 패널구조 모델의 중앙부에서의 최대 손상변형을 비교하여 추정하고자 한다. 이것은 다음 단계의 선수 구조부의 동적 구조해석의 검증에 사용될 것이다. 본 연구에서는 극치 6.5MPa, 후부높이 1.0MPa, 그리고 지속시간 5.0msec인 파랑충격압력 곡선 하에서, 강성이 작은 보강재로 보강된 경우 파랑충격하중의 면적은 $1.5s{\times}1.5s$ 보강재 간격(s), 강성이 큰 스트링거로 보강된 경우는 $2.5s{\times}2.5s$로 추정하였다.