• 한국해안해양공학회지
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• 제16권4
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• pp.233-240
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• 2004

도파고를 산정하는 경험식을 도출하기 위하여 도파지점에서의 수리조건을 대표하는 수치를 적용한 새로운 무차원수인 파활동경사 $S_x$를 도입하였다. Saville(1958)의 실험자료에 기초하여 사면경사, 파형경사 등과 도파고비와의 관계를 도출하여 수심 구간별로 도파고를 산정할 수 있는 경험식을 제시하였다. 한편 Ahrens(1988) 관측자료와 Mase(1989) 실험자료를 이용하여 조도 영향을 고려하며 광범위한 경사조건에 적용할 수 있는 보다 일반성이 확보된 경험식을 도출하였다. Mase(1989)가 시도한 바와 같이 Iribarren 수를 도입한 경우에는 비선형관계가 유도되어 지수형 산정식이 도출된다. 이에 반하여 지점 파활동경사를 도입하였을 경우에는 단순히 선형 비례하는 간단한 일차식의 형태로 광범위한 수심과 경사 구간에 적용할 수 있는 경험식을 도출할 수 있었다.

• 한국의류산업학회지
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• 제6권1호
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• pp.17-22
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• 2004

The purpose of this study was to obtain the basic element of patterns, which is the motif, from the existing art works and use it to create and simulate a variety of patterns to show the practical use of the computer. Natural dyed works of geometric shapes like squares and 1/4 of circles, each dyed with a different natural dyes, were produced and motifs were extracted. Then using the 4D box in Adobe Photoshop v.6.0, the developing pattern change and simulation effects when using different patterns and different repetition settings were examined. Observations were made as the motifs were replicated. Different patterns like a diagonal line, a square and a circle appeared. In order to find out the effects according to the changes, the motifs from work's square portions, circle centre, and the composition of eight motifs were extracted and used. The repeated patterns according to the extracted motifs simply showed that in the case of just repeating and arranging, square patterns appeared. By replicating and arranging, the motif and the allophone were matched and patterns with regular lines were formed, like a twill, pointed twill line. By setting the direction to Y and X in the repetition methodes, a typical half-drop arrangement or a brick pattern arrangement were formed according to 1/4, 2/4, 3/4, 1/3, or 2/3 in changes. Also the steepness of the slope changes quickly or in turn slowly as the rhombus shape appears. However in the case of a composed motif, an ogee pattern appeared. Lastly, by 3-D mapping patterns like a slant line, pointed twill patterns, diamond patterns, and the repeat patterns of a motif with a circle and a line combined, and a circle motif, an optical illusion could be observed.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.1-10
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• 2012

The annual energy production of Gangwon wind farm was predicted for three consecutive years of 2007, 2008 and 2009 using commercial programs, WindPRO and WindSim which are known to be used the most for wind resource prediction in the world. The predictions from the linear code, WindPRO, were compared with both the actual energy prediction presented in the CDM (Clean Development Mechanism) monitoring report of the wind farm and also the predictions from the CFD code, WindSim. The results from WindPRO were close to the actual energy productions and the errors were within 11.8% unlike the expectation. The reason for the low prediction errors was found to be due to the fact that although the wind farm is located in highly complex terrain, the terrain steepness was smaller than a critical angle($21.8^{\circ}$) in front of the wind farm in the main wind direction. Therefore no flow separation was found to occur within the wind farm. The flow separation of the main wind was found to occur mostly behind the wind farm.

• 대한토목학회논문집
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• 제39권6호
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• pp.769-777
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• 2019

이안제와 잠제(인공리프)와 같은 저 마루높이 구조물은 수중구조물은 연안역의 침식 등의 대책으로 일반적으로 사용되고 있다. 이러한 구조물의 피복재 안정성은 비월파조건의 구조물 보다 낮을 수 있다. 기존 연구에서는 대부분 사석으로 피복된 구조물을 대상으로 안정성을 검토하였다. 본 연구에서는 테트라포드로 피복된 저 마루높이 구조물과 수중구조물을 대상으로 안정성을 검토하기 위해 2차원 수리실험을 수행하였다. 피복재 안정성은 구조물 상부, 전사면 및 후사면을 대상으로 파형경사와 여유고를 변화시키며 검토하였다. 피복재의 주된 피해는 전사면 상부와 바다측 마루부에서 발생하였다. 실험결과를 이용하여 테트라포드의 안정계수를 산정할 수 있는 경험식을 제안하였다.

• 대한조선학회논문집
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• 제43권5호
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• pp.529-537
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• 2006

International Maritime Organization (IMO) is planning to include the Alternative Assessment of the Weather Criterion in the new Intact Stability (IS) Code to be revised. In this study, the procedure of the model test in the Interim Guidelines was reviewed by carrying out the model test and analyzing the test results. For this purpose, RO/RO passenger ship whose ratios of breadth to draft and the height of weight to draft were above 3.5 and above 0.6 respectively was selected as a test ship. Drifting test and motion test in regular waves were performed to estimate the hydrodynamic heeling lever and roll-back angle. Motion tests in waves were carried out in the three wave steepness conditions to measure roll-back angle and examine the feasibility of so called, the Three-step method. Using the test data, satisfaction of the Weather Criterion was assessed for the test ship by using the alternative method and compared with the current method.

• 한국해안해양공학회지
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• 제13권4호
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• pp.263-272
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• 2001

최근 우리나라에서는 slit형 케이슨을 적용한 방파제 건설이 시도되고 있다. slit 케이슨 방파제는 수심이 비교적 깊은 해역에 적절하며, 다수의 실험적.이론적 연구가 수행되었다. 본 연구에서는 불규칙파를 적용한 2차원 수리모형실험을 실시하여 종 slit형 케이슨 방파제의 반사특성을 검토하였다. 실험은 단일 유수실과 이중 유수실을 가지는 종 slit형 케이슨 방파제에 대해 유공율, 유수실의 폭 및 slit의 수 등을 달리한 여러 가지 실험안을 설정하여 수행하였다. 실험결과에 의하면, 파형경사가 작을수록 반사율은 크게 나타남을 알 수 있다. 그리고 규칙파를 적용한 기존 연구결과에 의하면 상대유수실 폭 (B/L)이 0.2-0.25 부근에서 최소 반사율을 보였으나, 불규칙파를 적용한 본 연구에서는 B/L$_{s}$ ,=0.13~0.15 범위에서 최소의 반사율을 보였다. 또한 동일한 유공율 조건에서 slit의 폭이 클수록 반사율이 낮게 나타났으며, 전체적으로 단일 유수실보다 이중 유수실의 경우가 소파효과가 우수하였다.

• 한국해안해양공학회지
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• 제8권3호
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• pp.221-230
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• 1996

기존의 전유공 케이슨 방파제로부터의 파 반사를 계산하기 위하여 개발된 Suh and Park의 이론 모형을, 케이슨 전면 하부의 연직벽을 경사가 매우 급한 경사벽으로 가정함으로써, 부분 유공 케이슨 방파제에 적용하였다. 또한, 이 모형에서, Kano and Liu가 제안한 차단계수를 이용하여 유공벽에서의 관성저항항을 수정하였다. 이 모형을 1993년도에 보고된 Park et al.의 수리실험 자료와 비교해 본 결과, 실험 자료 및 이론 모형 결과에서 모두 관성저항의 영향이 중요하여 B/L$_{c}$가 약 0.2일 때 반사율이 최소가 됨을 보이는데 (여기서 B=유수실의 폭, L$_{c}$=유수설 내에서의 파장), 이 값은 찬성저항의 영향을 무시했을 때 얻어지는 값 0.25보다 약간 작은 값이다. 또한 선형파 이론에 근거한 이 모형은 파의 비선형성이 증가함에 따라 반사율을 크게 계산하는 경향이 있음을 보이며, 따라서 이 모형은 파형경사가 작은 통상파에 적용하는 것이 바람직함을 알 수 있었다.있었다.

• 대한토목학회논문집
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• 제14권3호
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• pp.619-633
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• 1994

천해역(淺海域)에서 굴절(屈折), 회절(回折) 및 쇄파(碎波)를 고려한 범용성(汎用性)있는 파랑변형모형(波浪變形模型)을 개발하였다. 기존(旣存)이 완경사방정식(緩傾斜方程式)으로부터 고차(高次)의 회절항(回折項)을 고려한 포물형근사방정식(抛物形近似方程式)을 유도하였으며, 난류모형(亂流模型)을 도입하여 저면마찰(底面摩擦) 및 쇄파(碎波)에 의한 에너지 감쇠항(減衰項)을 정식화(定式化)하였다. 본 모형(模型)의 수치해(數値解)는 Crank-Nicolson의 음해법(陰解法)으로 계산하였으며, 계산결과(計算結果)는 원형천퇴(圓形淺堆), 타원형천퇴(楕圓形淺堆) 및 쇄파대(碎波帶)에서의 여러가지 수리실험결과(水理實驗結果)와 비교하였다. 쇄파대(碎波帶)에서 파고감쇠양상(波高減衰樣相)은 입사파(入射波)의 파형경사(波形傾斜)에 따라 민감(敏感)하게 반응(反應)하였으며, 타원형천퇴(楕圓形淺堆) 주변(周邊)에서 비선형분산관계(非線型分散關係)와 에너지 감쇠효과(減衰效果)는 파고변화(波高變化)를 잘 설명하였다. 그리고 본 모형(模型)을 현지해안(現地海岸)에 적용하여 타당성(妥當性)있는 계산결과(計算結果)를 얻었다.

• 한국농공학회논문집
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• 제48권7호
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• pp.3-14
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• 2006

The objective of this study was to develop a GIS-based decision support system (GIS-USLE system) to estimate soil erosion and evaluate its effect on concentrated upland plots in Godang district, Korea. This system was developed for the ArcView environment using A VENUE script. Three modules were used in the GIS-USLE system, namely pre-processing, the USLE factors calculator module, and post-processing. This system benefits from a user friendly environment that allows users with limited computer knowledge to use it. This system was applied to 1,285 individual upland plots ranging from 0.005 to 1.347 ha in size with an average slope steepness of 14 %. The rainfall distributions were estimated using the three methods, namely Mononobe and Yen-Chow with Triangle and with Trapezoid type, and then used to calculate the rainfall erosivity factor. The soil erosion amounts from the 1,285 individual plots in the study area by 2 year return period with a 24h maximum rainfall amount of 154.6 mm were estimated at 5 tons/ha on average. Slope appeared to be the most important factor affecting soil erosion estimation, as expected. The prototype model was applied to the project area, and the results appeared to support the practical applications. By examining many fields simultaneously, this system can easily provide fast estimation of soil erosion and thus reveal the spatial pattern of erosion from fields in a region. This study will help estimate and evaluate soil erosion in concentrated upland districts and identify the best management practices.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권4호
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• pp.569-579
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• 2013

A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005), and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011) proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011), and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011) was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974) that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011). The method of Kweon (2011) was already verified in the real sea test of Kweon et al. (2012), where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011) can be satisfactorily used for estimating the uplift force of a pile.