• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.2
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• pp.100-108
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• 1998

Morison formula has been used in the determination of wave forces acting on vertical cylindrical piles of ocean structures. The formula, however, can be applied to mildly varying varying incident waves with symmetrical shapes. The breaking waves impinge on structures with very high impact forces, which completely differ from the inertia and drag forces of the Morison formula in both magnitudes and characteristics. In the present study, a boundary element method is applied to determine the water particle velocity and acceleration under the breaking waves. A numerical model is then developed to determine breaking wave forces utilizing those water particle kinematics. The results of the model is then developed to determine breaking wave forces utilizing those water particle kinematics. The results of the model agree well with existing experimental data, giving maximal wave forces 3 times and maximal moments 5 times larger than the Morison formula does.

• 한국해양학회지
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• v.26 no.4
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• pp.340-349
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• 1991

From tidal current measurements on a tidal sand ridge in the Gyeonggi Bay from August 24 to September 29, 1987, tidal current velocities at 1.0 m above bottom (U/SUB 100/) and boundary shear velocities (U/SUB */) are calculated. The mean speeds of tidal current for flood and ebb over the entire period are 56.3 cm/sec and 63.7 cm/sec in mid-depth (9.0 m above bottom), and 43.9 cm/sec and 43.8 cm/sec in near-bottom (1.5 m above bottom). The exponent(P) in "power law", which is generally used for extrapolation from the mid-depth current velocity to that at the top of nationally logarithmic layer, is estimated to be 0.15 in the study area. Using logarithmic velocity profile assumption, mean values of U/SUB 100/ and U/SUB */ are calculated to be 41.4 cm/sec and 2.39 cm/sec, respectively. The mean value of U/SUB */ (2.39 cm/sec) is much higher than the critical shear velicity (U/SUB *c/) of 1.40 cm/sec reported by Choi (1990). and thus, it can be suggested that the most of sands on the tidal sand ridge in the study area are easily eroded and transported for the greater part of tidal period.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.14-20
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• 2015

The Korea ministry of land, infrastructure and transport set the goal of cutting greenhouse gas emissions from the transport sector by 34.3% relative to the business as usual scenario by 2020. In order to achieve this goal, support is being given to education and information regarding eco-driving. As a practical measure, however, a vehicle control strategy for decreasing fuel consumptions and emissions is necessary. Therefore, this paper presents an optimized driving model in order to decrease fuel consumption. Scenarios were established by driving mode. The speed profile for each scenario applied to Comprehensive Modal Emission Model and then each fuel consumption was estimated. Scenarios and speed variation with the least fuel consumption were derived by comparing the fuel consumptions of scenarios. The optimized driving model was developed by the derived the results. The speed profiles of general driver were collected by field test. The speed profile of the developed model and the speed profile of general driver were compared and then fuel consumptions for each speed profile were analyzed. The fuel consumptions for optimized driving were decreased by an average of 11.8%.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.35-35
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• 2019

현호색속은 양귀비과에 속하는 분류군으로서 전 세계에 약 450분류군이 분포하며 한국에는 25분류군이 분포한다. 20분류군의 한국산 현호색속 식물을 대상으로 화부 형태, 밀선의 형태, 밀선의 부착 위치를 비교 분석하였다. 현호색속 식물의 꽃은 좌우대칭하며 외화판의 거(spur)에 위치한 밀선을 갖는데 밀선의 위치, 형태 등은 현호색속의 분류체계를 반영하는 중요한 형질로 판단된다. 관찰결과 현호색절과 가는괴불주머니절의 밀선은 거(spur)의 1/3~2/3 정도 까지 신장되며 신장부는 매우 가늘지만 선단부에서는 다소 부푼 후 뾰족해지고 아래쪽으로 굽으며 분비조직이 위치하고 있는 부분은 녹색, 신장부는 횐색을 띠었다. 들현호색절에서는 거(spur)의 중간 정도에 위치한다. 기부는 두껍고 화색과 같은색을 띠지만 끝부분은 가늘고 굽지 않으며 흰색을 띤다. 자주괴불주머니절의 밀선은 거의 신장되지 않고 주걱형이며 노란색을 띠었다. 산괴불주머니절에서는 거(spur)의 3/4까지 신장되며 선단부는 뾰족하고 녹색을 띠며 아래로 굽는다. 밀선의 형태는 거(spur)의 형태와 관련이 있다. 거(spur)가 주머니처럼 부푸는 절에서 밀선분비조직의 뚜렷한 발달이 관찰되고 거(spur) 안에 분비된 화밀을 저장한다. 비록 현호색절과 산괴불주머니절이 서로 밀접한 계통을 갖지는 않지만 이들이 공유하는 밀선의 형태는 거(spur) 형태의 유사성에서 기인한 것으로 보인다. 한국산 현호색속 밀선의 형질진화 분석을 위하여 mesquite을 이용하여 ancestral reconstruction를 수행하였다. 밀선의 형질진화는 한국산 현호색속 5절의 계통진화를 반영하였다. 현호색속의 화부형질은 매우 복잡하고 다양한 방향으로 진화한 것으로 보이며 이를 이해하기 위해서는 다양한 화부형질의 종합적인 검토가 필요하다. 이번 연구에서 확인된 화부구조와 분비조직의 형질은 현호색속의 계통진화를 잘 반영하고 있었으며 향후 분비조직의 해부형질, 미세형질 등의 추가연구를 통하여 현호색속의 계통연구를 위한 새로운 분류학적 가치를 제공할 수 있을 것이다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.1
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• pp.11-19
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• 2012

Due to existing infrastructure to collect traffic information was constructed to expressway and national highway, we cannot precisely know traffic situation for their surrounding area. Therefore, it is difficult to provide reliable traffic information to users using navigation and smartphone. In this research, we collected aerial images by using unmanned airship capable of wide-area monitoring and proposed a method extracting vehicle speed from the collected data. And, we performed experiments to verify the accuracy of extracted vehicle speed. Our method proposed in this research can be used to extract a new approach of traffic information according to increased demand of traffic monitoring. We expect that our method will become a new research trend in traffic information application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.155-158
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• 2003

The effects of Mn, V addition on the behavior of structure and the effects of cooling rate of S20C steel for use of Tn housing and valve for automotive parts have been investigated. Transformation start temperature measured from inflection point of cooling curves has been found out to decrease with increasing cooling rate and to be more sensitive to Mn contents when cooling rate is fast. It was therefore shown that the grain was refined. If there is a big compacting pressure, it is indicated that hardness becomes much greater at surface than inside.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.122.2-122.2
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• 2011

결정질 태양전지 제작에서, passavtion은 표면의 반사도를 줄여주는 반사 방지막의 역할과 표면의 dangling bond를 감소시켜, 표면 재결합 속도를 줄이고 minority carrier lifetime을 증가하는 데 큰 영향을 미친다. 그렇기 때문에 저가형 고효율 태양전지 제작에서 우수한 특성을 가지는 passivation막은 매우 중요한 이슈이다. 본 연구에서는 LBC(local back contact) 구조를 가지는 단결정 태양전지 후면에, 기존의 Full Al-BSF의 passivation 막을 SiNx와 ONO passivation 막으로 각각 대체하여, LBC 구조에서 더 적합한 passivation 막을 찾고자 하였다. SiNx와 ONO passivation 막은 단결정 LBC 구조 태양전지 후면에 각각 형성되었고 $800^{\circ}C$, 20 sec 조건으로 소성되었다. 실험결과는 minority carrier lifetime과 surface recombination velocity로 관찰하였다. 그 결과, SiNx passivation 막의 표면 재결합 속도는 29.7cm/s이고, ONO passivation 막의 표면 재결합 속도는 24.5cm/s로, Full Al-BSF 표면 재결합 속도 750cm/s에 비해 더 적합한 passivation 막으로 확인할 수 있었다. 결과적으로 SiNx,ONO passivation 막이 Full Al-BSF보다 전극에 수집되는 캐리어의 양이 많아짐에 따라 효율향상을 가져올 수 있을 것이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.639-650
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• 1999

In this paper, a chattering alleviation VSS controller for the sinusoidal type BLDC motor is designed. Dead Zone function is proposed to change the chattering occurring in the transient state from high frequency to low frequency and time-varying gains are applied for the control input to eliminate the steady state excessive chattering in the conventional ISM. The proposed Dead Zone function represents the sliding layer composed of two switching surfaces and if a state vector exists in this layer, the chattering don't occur. Simulation and experimental results confirm the useful effects of the above algorithm.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.664-667
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• 2010

Solid rocket propulsion systems are generally used for tactical missiles due to the structural and operational simplicity. Nevertheless, various kinds of design factors including outer diameter, length, weight, loading efficiency of propellant grain effects to thrust performance. Dual thrust is beneficial to range extension and terminal velocity increasement. But loading efficiency becomes low in case to obtain dual thrust performance by burning surface control. So, It is predicted to be reasonable to obtain dual thrust performance with high/low burning rate propellants. This study is on internal ballistic analysis and ground test to confirm dual thrust performance.

• Journal of the Korean Magnetics Society
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• v.22 no.4
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• pp.136-141
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• 2012

In the this research, two simultaneous peaks of radial artery pulse wave and ECG pulse wave measured by using clip-type pulsimeter and ECG were investigated in order to analyze pulse wave velocity. The measured value of a pulse wave velocity is about 5~7 m/s, it is proved one new method to measure an exact value of pulse wave velocity more than the typical biomedical signal monitoring system. This result implies that data measured by the oriental medical diagnosis apparatus as pulsimeter is clinically used in future.