• 한국해양학회지
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• v.30 no.6
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• pp.550-564
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• 1995

The temporal and spatial characteristics of wind fields over the neighbouring seas of the Korean peninsula are investigated using 10-years daily wind data during 1978${\sim}$1987 which have been spatially smoothed and low-pass filtered. Long term annual and monthly means are examined for synoptic patterns and spectral analyses are made for temporal variability and spatial coherence. Spatial patterns of the annual mean wind stress and curl have a strong resemblance with those of monthly means during the winter season. Two outstanding periodicities are observed at 1 and 2 cycles per year. The synoptic winds over the study area are highly coherent at both the annual and semi-annual periodicities. However, each basin has its own characteristic spatial pattern. For instance, the prevailing wind during the winter season is northerIy over the northern East Sea (ES), Yellow Sea (YS), and northern East China Sea (ECS), while it is northwesterly over the southern ES and northesterly over the northern ES and southern ECS. At the same time, the wind stress curl is positive over the northern ES and southern ECS, while it is negative over the southern ES, YS and northern ECS. On the other hand, the wind field during the summer season, with its strength being much reduced, is completely different from that during the winter season, and frequent passage of tropical storms provokes large temporal variability over ECS. One remarkable point is that the annual cycle, dominated by the Siberian High, tends to propagate from northeast to southwest, i.e., from northern 25 toward southern ES, YS and ECS, while the semi-annual cycle propagates in the opposite direction, from southwest to northeast. The semi-annual periodicity may reflect development of extratropical cyclones in spring and fall which frequently cross the Korean peninsula. In higher frequencies, there are no dominant periodicities, but local winds over YS and ES are highly correlated for frequencies larger than 0.1 cycles per day and phase difference increases linearly with frequency. This linear increase of phase corresponds to phase speed of 550 and 730 km/d at 0.1 and 0.3 cpd, respectively, The phase speed is apparently coincident with moving speed of extratropical cyclones across the Korean peninsula in the west-east direction.

• Journal of Korea Multimedia Society
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• v.9 no.7
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• pp.872-893
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• 2006

In this study, I classify the elements of physiognomic judgment of character with regard to form and meaning from a visual perspective based on physiognomic judgment of character study in 'the cosmic dual forces and the Five Elements theory'. Individual characters for each type are designed using graphic data. Based on that, design system of individual characters for each personality type is investigated using Neural Network system. Faces with O-Haeng (Five Elements) shapes are shown to constitute the system with ${\pm}0.3%$ degree of error tolerance for the non-loaming input data. For the shapes of Chinese characters 'tree, fire, soil, gold and water', their MSE(Mean Square Error) are 0.3, 0.3, 0.2, 0.5, 0.2. It seems to be the best regarding the scoring system which ranges from 0 to 5. Therefore, this system might be regarded to produce the most accurate facial shape of character automatically when we input character's personality we desire to make.

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.57-68
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• 1983

To estimate the possible amount of weed-crop competitions under the various cropping patterns of two rice cultivars of different type, comparisons between weedy check and weed-free plots in plant height, tillering number, and plant weight were investigated. Fluctuations in Importance Value, competition value, and net productivities were used to discuss the crop-weed competition, respectively. As a result, differences in dominant weed species, competitive crop variety, most effective cropping pattern, and crop yielding characteristics under the different weed competitions were investigated, respectively.

• Explosives and Blasting
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• v.9 no.1
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• pp.3-13
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• 1991

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill ${\phi}70mm$ on the calcalious sand stone (soft -modelate -semi hard Rock). The total numbers of test blast were 88. Scale distance were induced 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ were V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum charge per delay-period of eight milliseconds or more (kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents where the quantity $\frac{D}{W^b}$ is known as the scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagorized in three groups. Cubic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge Per delay Plots of peak particle velocity versus distoance were made on log-log coordinates. The data are grouped by test and P.P.V. The linear grouping of the data permits their representation by an equation of the form ; $V=K(\frac{D}{W^{\frac{1}{3}})^{-n}$ The value of K(41 or 124) and n(1.41 or 1.66) were determined for each set of data by the method of least squores. Statistical tests showed that a common slope, n, could be used for all data of a given components. Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m ------- under l00m ${\cdots\cdots\cdots}{\;}41(D/sqrt[2]{W})^{-1.41}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}A$ Over 100m ${\cdots\cdots\cdots\cdots\cdots}{\;}121(D/sqrt[3]{W})^{-1.66}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}B$ where ; V is peak particle velocity In cm / sec D is distance in m and W, maximLlm charge weight per day in kg K value on the above equation has to be more specified for further understaring about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.128-137
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• 2013

Due to the global warming and air pollution, interest in renewable energies has increased in recent years. In particular, the crisis of the depletion of fossil energy resources in the near future has accelerated the renewable energy technologies. Among the renewable energy resources, oceans covering almost three-fourths of earth's surface have an enormous amount of energy. For this reason, various approaches have been made to harness the tremendous energy potential. In order to achieve two purposes: to improve harbor water quality and to use wave energy, this study proposed a sea water exchange structure applying an Oscillating Water Column (OWC) wave generation system that utilizes the air flow velocity induced by the vertical motion of water column in the air chamber as a driving force of turbine. In particular, the airflow velocity in the air chamber was estimated from the time variations of water surface profile computed by using 3D-NIT model based on the 3-dimensional irregular numerical wave tank. The relationship of the frequency spectrums between the computed airflow velocities and the incident waves was analyzed. This study also discussed the characteristics of frequency spectrums in the air chamber according to the presence of the structure, wave deformations by the structure, and the power of the water and air flows were also investigated. It is found that the phase difference exists in the time series data of water level fluctuations and air flow in the air chamber and the air flow power is superior to the fluid flow power.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.183-192
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• 2008

Stone cultural heritages in Korea are mostly situated out door without any notable protection thus there are severe damage from chemical and biological weathering. This in turn, causes deformation and structural damage. To counter act this problem and to increase durability, various kinds of conservation materials are used in the conservation and restoration treatment. However, there are not many practical and technological experiment done on this subject. This paper attempts quantitative evaluation of effectiveness of ethylsilicate based resin for Namsan granite in Gyeongju. When two different materials with different ethylsilicate concentration were compared, the result indicated decrease of absorption and porosity with increase of ultrasonic velocities, uniaxial compressive strength, elastic constant, tensile strength and Poisson's ratio. In addition, comparison of physical characteristic of the conservation material resulted favorably toward ones with higher concentration of ethylsilicate. This is due to the ethylsilicates characteristic to fill the internal pores of stone. There is discolouration of stone surface after treatment with conservation material. This was more prominent with the product of higher ethylsilicate concentration.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.2
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• pp.127-138
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• 1996

The strip method, unified theory and 3-D panel method are commonly used methods for the seakeeping analysis of high-speed vessels. The strip method which is basically 2-dimensional method is known to give incorrect hydrodynamic coefficients and motion responses for the cases of high speed and low frequency region. And the unified theory which uses two dimensional approach in inner domain and slender body theory in outer domain is very complicate in computational modelling. Though the 3-D panel method requires comparatively long computation time, it is believed that the method gives good results without any limitation in ship speed and range of frequency for computation. In the 3-D panel method the source singularity representing translating and pulsating Green function is used and Hoff's method is adopted for the numerical calculation of the Green function. The computation time can be reduced by using the symmetry relationship with respect to longitudinal axis. In this paper the strip method and the 3-D panel method are compared for the seakeeping analysis of a high-speed catamaran. The Compared items are the hydrodynamic coefficients, wave exciting forces, frequency response functions and short-term responses in irregular waves.

• Economic and Environmental Geology
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• v.40 no.1 s.182
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• pp.87-101
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• 2007

A variety of informations obtained from satellite image, digital elevation relief map (DEM), borehole logging, televiewer, geophysical prospecting, etc were synthetically analyzed to investigate subsurface geological and structural characteristics and to evaluate geohazard pertinent to fault-damage in the Busan metropolitan city. It is revealed that the geology is composed of the Cretaceous andesitic$\sim$dacitic volcanics, gabbro, and granitoid and that at least three major faults including the Dongrae fault are developed in the study area. Based on characteristics of topography, fault-fractured zone, and isobath maps of the Quaternary sediments and weathered residuals of the basement, the Dongrae fault is decreased in its width and fracturing intensity of damaged zone from south toward north, and the fault is segmented around the area between the Seomyeon and Yangieong junctions. Meanwhile, we drew a geohazard sectional map using the five major parameters that significantly suggest damage intensity of basement by fault, i.e. distance from fault core, TCR, RQD, uniaxial rock strength, and seismic velocity of S wave. The map is evaluated as a suitable method to express the geological and structural characteristics and fault-damaged intensity of basement in the study area. It is, thus, concluded that the proposed method can contribute to complement and amplify the capability of the present evaluation system of rock mass.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.114-131
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• 1992

In the present work, a two-dimensional boundary-value problem for a large amplitude motion is treated as an initial-value problem by satisfying the exact body-boundary and nonlinear free-surface boundary conditions. The present nonlinear numerical scheme is similar to that described by Vinje and Brevig(1981) who utilized the Cauchy's theorem and assumed the periodicity in the horizontal coordinate. In the present thesis, however, the periodicity in the horizontal coordinate is not assumed. Thus the present method can treat more realistic problems, which allow radiating waves to infinities. In the present method of solution, the original infinite fluid domain, is divided into two subdomains ; ie the inner and outer subdomains which are a local nonlinear subdomain and the truncated infinite linear subdomain, respectively. By imposing an appropriate matching condition, the computation is carried out only in the inner domain which includes the body. Here we adopt the nonlinear scheme of Vinje & Brevig only in the inner domain and respresent the solution in the truncated infinite subdomains by distributing the time-dependent Green function on the matching boundaries. The matching condition is that the velocity potential and stream function are required to be continuous across the matching boundary. In the computations we used, if necessary, a regriding algorithm on the free surface which could give converged stable solutions successfully even for the breaking waves. In harmonic oscillation problem, each harmonic component and time-mean force are obtained by the Fourier transform of the computed forces in the time domain. The numerical calculations are made for the following problems. $\cdot$ Forced harmonic large-amplitude oscillation(${\omega}{\neq}0,\;U=0$) $\cdot$ Translation with a uniform speed(${\omega}=0,\;U{\neq}0$) The computed results are compared with available experimental data and other analytical results.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.10b
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• pp.15-15
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• 1994

M MA ODS 합금의 보다 폭넓용 실용확훌 위해 크게 요구되고 있는 적정 접합기술 개발의 한 방안￡로, 마찰압접(Friction Welding) 방법의 가능성옳 조사하기 위하여 마찰압력과 시간, 마 찰 후 접촉압력(Upset Pressure) 풍을 다양하게 변화시켜 접합체톨 제조한 후, 접합체 강도에 대한 인장시험과 접합계연의 결합 및 미세구조에 대한 현미경 관찰, EDS에 의한 원소분석, 접 합이옴부의 경도분포와 파단면 분석 풍율 행하였다. 실험에 사용된 모재는 기계적 합금법으로 제조된 Inca사의 Ni기 MA 754 합금이었으며, 직경 l 10 mm, 길이 50 mm로 가공한 후, 아세통￡로 초음파 세척하여 접합에 사용하였다. 접합온 브 레이크식 마찰압접기틀 사용하여 행하였으며, 회전시험편의 회전수는 2400 rpm이었A며, 다른 한쪽의 고정시험편과의 마찰압력 및 마찰시간온 각각 50 - 500 MPa과 1-5초로, 또한 업셋압 력도 50 - 600 MPa로 변화시켰다. 이때 업셋압력은 모든 시편에 대해 일정하게 6초동안 가하 였다. 얻어진 접합체는 각 압접조건 당 2개 이상의 접합시험편에 대해 상온 인장강도톨 측정하 였으며, 파단이 일어난 위치를 확인한 후 파면에 대한 분석율 주사전자현미경(SEM)과 에너지 분산형 분광분석기mDS)릎 사용하여 행하였다. 컵합이옴부의 첩합성올 확인하기 위하여, 접합 체를 접합변에 수직으로 절단, 연마한 후 광학현미경과 SEM, EDS 퉁으로 관찰, 분석하여 접 합부의 형상과 결합형성 여부, 접합계면의 미세조직 퉁옳 조사하였다. 또한 마찰압접에 따론 모재와 접합계연부의 경도분포훌 접합이옴부로부터 모재쪽으로 일정 간격율 두어 마이크로 비 커스 경도기로 측정, 조사하였다. 이상의 설험 결과, 다옴과 같온 결론옳 얻었다. ( (1) 접합체 강도가 모채 강도의 95% 이상이 되는 양호한 렵합체흩 얻기 위한 마찰압력 조건 온, 2400 rpm의 회전속도와 6초의 업셋압력 유지시간에서 마찰압력과 업셋압력, 그리고 마찰시 간이 각각 400 MPa 이상과 500 MPa 이상,2초입율 확인하였다. ( (2) 컵합이옴부의 관찰 결과, 모든 마찰압접 조건에서 컵합이옴부는, 기폰 모재의 texture 조직 을 유지하고 있는 모재부 영역(영역 ill)과 첩합계면부에 인접하여 업셋압력이 주어질 때 단조 효과에 의해 계연 외부로 metal flow가 일어나면서 형성된 영역 II, 매우 미세한 결정립으로 구성된 중앙부의 영역 1 로 이투어져 있옴융 확인하였다. ( (3) 최적접합조건이 충족되지 않온 경우, 접합부의 영역 I 에서 관찰된 void와 균열, 불균일한 접합계면 통의 접합결함에 Al과 Y. Ti 퉁￡로 구성된 산화물률이 용집되어 있옴을 확인하였 다-( (4) 접합체의 파단 양상온 크게 접합부 파단과 모재부 파단, 이률의 혼합형 파단i로 나눌수 있었다. 모재부 파단의 경우, 파단면이 매끄럽고 파변상의 결정립도 매우 미세하였으며, 산확물 의 용집도 찾아보기 어려웠 나, 접합부 파단의 경우에는 파변의 굴곡이 비교척 심하고 연성 입계파괴의 형태를 보였￡며, 결정립도 모채부 파단의 경우에 비해 조대하였다. 조대하였다.