• 대한원격탐사학회지
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• 제27권5호
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• pp.535-542
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• 2011

본 연구에서는 서남극 Canisteo 반도와 그 주변 지역이 촬영된 2쌍의 ERS-1/2 tandem pair에 4-pass DInSAR 기법을 적용하여 표면 변위도를 생성하였고, 빙하와 해빙의 표면 변위를 해석하였다. 표면 변위도에서 빙하는 매우 빠른 움직임을 나타냈으며 인접해 있는 정착빙을 밀어내어 정착빙 표면에서는 빙하와 같은 방향의 변위가 관찰되었다. Cosgrove 빙붕도 큰 변위를 나타냈으며, 인접해 있는 정착빙을 밀어내는 것이 관찰되었다. 일부 해빙은 정착빙과 반대 방향의 움직임을 보였다. 이는 해빙이 해류에 영향을 받는 유빙이기 때문이며, 이로부터 정착빙과 유빙의 경계를 확인할 수 있었다. 빙붕과 빙상의 표면은 SAR영상에서 유사한 밝기를 보이며, 간섭도에서도 비슷한 정도의 간섭띠 변화율을 나타내 두 빙체를 쉽게 구분 할 수 없었다. 그러나 움직임이 큰 빙붕과 변위가 거의 없이 안정적인 빙상의 경계를 절대위상복원 후 생성한 변위도를 통해서 쉽게 확인할 수 있었다.

• 대한조선학회지
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• 제23권4호
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• pp.25-34
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• 1986

A two-dimensional linear method has been developed for the motion and the second-order steady force arising from the hydrodynamic coupling between waves and currents in the presence of a body of arbitrary shape. Interaction between the incident wave and current in the absence of the body lies in the realm beyond our interest. A Fredholm integral equation of the second kind is employed in association with the Haskind's potential for a steadily moving source of pulsating strength located in or below the free surface. The numerical calculations at the preliminary stage showed a significant fluctuation of the hydrodynamic forces on the surface-piercing body. The problem is approximately solved by using the asymptotic Green function for $U^2{\rightarrow}0$. The original Green function, however, is applied for the fully submerged body. Numerical calculations are made for a submerged and for a half-immersed circular cylinder and extensively for the mid-ship section of a Lewis-form. Some of the results are compared with other analytical results without any available experimental data. The current has strong influence on roll motion near resonance. When the current opposes the waves, the roll response are generally negligible in the low frequency region. The current has strong influence on roll motion near resonance. When the current opposes the wave, the roll response decreases. When the current and wave come from the same direction, the roll response increases significantly, as the current speed increases. The mean drift forces and moment on the submerged body are more affected by current than those on the semi-immersed circular cylinder or on the ship-like section in the encounter frequency domain.

• 농약과학회지
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• 제12권4호
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• pp.351-356
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• 2008

헬기에 의해 항공살포된 고농도 소량 살포농약의 비산 및 분포 특성과 이에 따른 벼와 주변작물에 미치는 영향을 평가하였다. 항공살포시 농약의 벼 부착량은 채취지점 및 약제에 따라 $3.1{\sim}4.7$배의 차이를 보여 살포 균일성은 낮았다. 헬리콥터에 의한 항공방제시 대상지역 이외의 포장으로 분무입자가 비산하는 정도는 바람부는 방향으로는 30 m, 바람부는 반대방향으로는 20 m 이내로 비교적 비산 정도가 낮았다. 살포된 농약은 대부분 벼에 부착되었고 논물 또는 토양 중에 낙하된 비율은 낮은 편이었으며, 재배환경 중 분해 속도는 벼> 물>토양 순이었다. 항공방제 포장의 벼 수확 후 토양 중살포농약의 잔류량은 불검출 ${\sim}0.201\;mg/kg$이었으며, 현미와 볏짚에서는 검출되지 않았다. 또한 항공살포에 의한 벼와 주변작물에 대한 약해반응은 무시할 수준이었다.

• Wind and Structures
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• 제27권4호
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• pp.213-221
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• 2018

In the desert and Gobi regions with strong wind and large sediment discharge, sand transporting engineering is more effective than sand blocking and sand fixing measures in sand prevention. This study uses the discrete phase model of 3D numerical simulation to study the motion trail, motion state and distribution rule of sand particles with different grain diameters when the included angle between the main shaft of the feather-row lateral transportation sand barrier and the wind direction changes, and conducts a comparison in combination with the wind tunnel test and the flow field rule of common sand barrier. According to the comparison, when wind-sand incoming flow passes through a feather-row sand barrier, sand particles slow down and deposit within the deceleration area under the resistance of the feather-row sand barrier, move along the transportation area formed by the transportation force, and accumulate as a ridge at the tail of the engineering. With increasing wind speed, the eolian erosion of the sand particles to the ground and the feather-row sand barrier is enhanced, and the sand transporting quantity and throw-over quantity of the feather-row sand barrier are both increased. When sand particles with different grain diameters bypass the feather-row sand barrier, the particle size of the infiltrating sands will increase with the included angle between the main shaft of the feather-row sand barrier and the wind direction. The obtained result demonstrates that, at a constant wind speed, the flow field formed is most suitable for the lateral transportation of the wind-drift flow when the included angle between the main shaft of the feather-row sand barrier lateral transportation engineering and the wind speed is less than or equal to $30^{\circ}$.

• 과학기술학연구
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• 제10권1호
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• pp.1-25
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• 2010

본 논문에서는 현대기술에 대한 랭던 위너의 철학적 분석을 자세히 소개하고' 그 의의를 평가함으로써 기술철학의 최근 동향과 나아가야 할 방향을 모색해 볼 것이다. 우선 1절에서는 위너가 기존 기술철학의 두 흐름' 즉 고전적 기술철학과 경험으로의 전환 사이에서 어떤 위치를 점하는지 알아보도록 한다. 2절부터 5절까지는 위너의 기술 이해' 현대기술사회에 대한 진단' 기존의 기술철학에 대한 비판적 분석' 현대 기술사회의 문제를 해결하기 위한 그의 제안 등을 차례로 검토한다. 6절에서는 위너 이론의 한계와 의의를 살펴본다. 위너의 지적 여정은' 기술철학의 이론들을 반성적으로 재검토하고' 이론적 연구와 더불어 실천성을 무시하지 않으며' 대중과의 소통을 시도했다는 점에서 향후 기술철학의 발전 방향에 시사하는 바가 크다.

• 산업경영시스템학회지
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• 제33권2호
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• pp.154-161
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• 2010

The conning display which is located in the ship bridge shows the various important information such as ship position, ship speed, track data, rate of turn, thruster rpm so on, and is one of the IBSs(Integrated Bridge Systems). In this study, the survey was conducted for ten officers to find the importance and using frequency of the information which were displayed in the conning display. The results showed that the information of drift speed, ship speed, wind direction and wind force, rate of turn, sea water depth, ship position, heading, thrust rpm, alarm, rudder command and angle got high scores and it meant that these information were very important and high frequency of use during the navigation. The optimized contents arrangement in conning display was suggested based on importance and using frequency of information. The experiment using eye-tracking system was conducted to compare the performance time and error rate of nine different scenarios for suggested arrangement display and three other existing displays. The results showed that the suggested arrangement was the best in performance time and error rate. The scenario concerning the direction and speed of wind showed faster performance time and lower error rate than other scenarios. The movement of subject's eye tended to search from the center and to avoid the comer, called 'the comer effect.' It is expected that the results of this study could help for the bridge staff to grasp the sailing information easily and to cope with the given situations promptly.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.257-262
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• 2002

Numerical model introduced in this study combines wave refraction-diffraction, breaking, bottom friction, lateral mixing, and critical shear stress and three sub-models for simulating waves, currents, and bottom change were briefly discussed. Simulations of beach processes and harbor sedimentation were also described at the coast neighboring Bangpo Harbor, Anmyundo, Chungnam, where the area has suffered from accumulation of drifting sand in a small fishing harbor with a wide tidal range. We also made model test for the case of a narrow tidal range at Nakdong river's estuary area to understand the effect of water level variation on the littoral drift. Simulations are conducted in terms of incident wave direction and tidal level. Characteristics of wave transformation, nearshore current, sediment transport, and bottom change are shown and analyzed. We found from the simulation that the tidal level impact to the sediment transport is very important and we should apply the numerical model with different water level to analyze sediment transport mechanism correctly. Although the model study gave reasonable description of beach processes and harbor sedimentation mechanism, it is necessary to collect lots of field observation data, including waves, tides and bottom materials, etc. for better prediction.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2014년도 춘계학술대회
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• pp.241-243
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• 2014

최근, 해안 침식 현상은 사회적, 경제적 측면에서 큰 영향을 미칠 수 있기 때문에, 각 지자체마다 각종 방지대책이 실시되고 있다. 그러나, 방지시설을 설치하기 전에 표사이동특성 등의 변화를 면밀히 검토하고, 이를 토대로 장기모니터링을 통한 지속적인 변화검토가 필수적이다. 본 연구에서는 현재 백사장 침식이 문제가 되고 있는 서해 중부 연안의 임의의 해빈(사빈)을 대상으로 장기 파랑특성분석을 통한 이상파랑, 계절별 탁월 파향, 파고, 주기 등을 고려한 평상파랑을 산정하고 이를 근거하여 수치모형실험을 통하여 파랑변형 및 표사이동에 대한 경향을 파악하였다.

• Wind and Structures
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• 제9권3호
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• pp.217-230
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• 2006

This paper describes a procedure to develop fragility curves for woodframe structures subjected to lateral wind loads. The fragilities are cast in terms of horizontal displacement criteria (maximum drift at the top of the shearwalls). The procedure is illustrated through the development of fragility curves for one and two-story residential woodframe buildings in high wind regions. The structures were analyzed using a monotonic pushover analysis to develop the relationship between displacement and base shear. The base shear values were then transformed to equivalent nominal wind speeds using information on the geometry of the baseline buildings and the wind load equations (and associated parameters) in ASCE 7-02. Displacement vs. equivalent nominal wind speed curves were used to determine the critical wind direction, and Monte Carlo simulation was used along with wind load parameter statistics provided by Ellingwood and Tekie (1999) to construct displacement vs. wind speed curves. Wind speeds corresponding to a presumed limit displacement were used to construct fragility curves. Since the fragilities were fit well using a lognormal CDF and had similar logarithmic standard deviations (${\xi}$), a quick analysis to develop approximate fragilities is possible, and this also is illustrated. Finally, a compound fragility curve, defined as a weighted combination of individual fragilities, is developed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.720-723
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• 2005

Ship motion is a complex controlled process with several hydrodynamic parameters that vary in wide ranges with respect to ship load condition, speed and surrounding conditions (such as wind, current, tide, etc.). Therefore, to effectively control ships in a designed track is always an important task for ship masters. This paper presents an effective adaptive autopilot ships that ensure the optimal accuracy, economy and stability characteristics. The PID control methodology is modified and parameters of a PID controller is designed to satisfy conditions for an optimal objective function that comprised by heading error, resistance and drift during changing course, and loss of surge velocity or fuel consumption. Designing of the controller for course changing process is based on the Model Reference Adaptive System (MRAS) control theory, while as designing of the automatic course keeping process is based on the Self Tuning Regulator (STR) control theory. Simulation (using MATLAB software) in various disturbance conditions shows that in comparison with conventional PID autopilots, the designed autopilot has several notable advantages: higher course turning speed, lower swing of ship bow even in strong waves and winds, high accuracy of course keeping, shorter time of rudder actions smaller times of changing rudder direction.