• Special Issue of the Society of Naval Architects of Korea
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• 2007.09a
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• pp.79-88
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• 2007

In this study, we improved the layout of deckhouse pre-erection area where erects the blocks and developed the pre-erection block arrangement system for the improvement of productivity and effectiveness. The major operating point of the pre-erection area is to fabricate as many as possible that has restrict area and working plate. The developed system has information management module, scheduling module, schedule control module, statistics module, and information integrate module. The heuristic algorithm is issued and evaluated with real data. And genetic algorithm is used for the evaluation of issued it.

• Current Research on Agriculture and Life Sciences
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• v.8
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• pp.1-8
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• 1990

The experiment was conducted to study on the germination of seeds, and chemical change in the endorsperm and embryo of maize seeds treated with gibbrellic acid(GA) 25, G A 50, bengyl adenine(BA) 100 and B A 200 ppm. Obtained results can be summerized as follows: 1. The germination rate in the initial stage of maize seed increased most with G A 25 ppm treated but decreased most with B A 200 ppm treatment amount other treated blocks. There is no significant difference between treatments in the middle and later stage of the seed germination. 2. The quantity of Q $CO_2$ was noticeably increased together in parallel with germination at each blocks, but such fact was found that the block of treatment has low Q $CO_2$ in comparison with control and in particular, has the tendency to take very low in B A 200 ppm. 3. The amount of reducing sugar and total sugars among embryo and endosperm are promptly increased at each blocks, but B A treatment shows low rate of increase in comparison with the non treatment and G A treatment. 4. The quantity of crude protein of seed during germination are increased at the part of embryo and decreased at the part of endosperm. Such degree is most prominent in the treatment with G A 25 ppm and changing degree of treatment with 200 ppm is lowest.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.559-561
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• 2008

본 논문에서는 실용적이며 신뢰성 있는 고전압 대용량 유도전동기 구동용 H-브릿지 멀티레벨 인버터를 개발하여 산업 현장에 적용한 내용을 소개하였다. 실용적인 PWM (Pulse Width Modulation)과 PEBB (Power Electronics Building Blocks)에 기초한 신뢰성 있는 분산 제어를 적용하였으며, H-브릿지 멀티레벨 인버터를 이용한 유도 전동기 벡터 제어시의 위상지연을 보상하여 제어 성능을 향상시켰다. 또한, Power Cell 고장 발생시 시스템을 정지하지 않으면서 효율적 운전을 가능하게 하는 3상 불평형 제어를 이용하여 잉여성을 확보하였다. 다양한 전압과 용량의 H-브릿지 멀티레벨 인버터를 설계 및 제작하여 각종 부하 실험, 산업 현장 적용을 통해 적용된 방법의 타당성과 실용성을 입증하였다. 또한 실제 제품 설계, 생산, 판매, 유지 보수 과정을 통해 설계의 유연성, 생산의 효율성, 유지 보수의 편리함, 그리고 사용자 요구에 대한 대응성이 우수함을 확인하였다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.172-180
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• 2013

The focus of this study is to provide a method for determining the dimension of a submerged breakwater satisfying the target transmission performance or predicting the transmission coefficient of a given structure. This method was developed based on data analysis of the physical experiment that was carried out by using the submerged breakwater composed of double-layer permeable blocks. Two different armor blocks of Tetrapod and Triangular Pyramid Block were used in the experiment. The parameter $K_Th_b/h$ was introduced in the analysis of the measurement data. By using the linear regression line deduced from the analysis of the experimental data, it was possible to readily predict the wave transmission coefficient irrespective different water depths at the crest of the submerged breakwater, under the condition of significant decrease in transmitted wave height due to the submerged breakwater. This method can be effectively utilized for estimating the necessary number of blocks used for the submerged breakwater as well as comparing the transmission characteristics of the submerged breakwater according to use of different armor blocks.

• Design & Manufacturing
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• v.16 no.4
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• pp.67-74
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• 2022

Injection molding is a cyclic process comprising of cooling phase as the largest part of this cycle. Providing efficient cooling in lesser cycle times is of significant importance in the molding industry. Recently, lots of researches have been done for rapid cooling of a hot-spot area using CO2 in injection molding. The CO2 flows under high pressure through small, flexible capillary tubes to the point of use, where it expands to create a snow and gas mixture at a temperature of -79℃. The gaseous CO2 removes heat from the mold and releases it into the atmosphere. In this paper, a CO2 cooling module was applied to an injection mold in order to cool a large area cavity uniformly and quickly, and the cooling performance of the injection mold was investigated. The product was a high-curvature molded part with a molding area of 300x100mm. Heat cartridges were installed in a stationary mold, and CO2 cooling module was inserted inside a movable mold. Through structural analysis, it was confirmed that the maximum deformation of mold with CO2 cooling module was 0.09mm. A CO2 feed system with a heat exchanger was used for cooling experiments. The CO2 was injected into the holes on both sides of the supply pipe of the cooling module and discharged through hexagon blocks to cool the mold. It took 5.8 seconds to cool the mold from an average temperature of 140℃ to 70℃. Through the experiment using CO2 cooling module, it was found that a cooling rate of up to 12.98℃/s and an average of 10.18℃/s could be achieved.

• Corrosion Science and Technology
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• v.14 no.2
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• pp.59-63
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• 2015

Airless spray which is widely used for painting to ship blocks and hull sides is the coating method for attaching atomized paint material to the substrate using spray tip nozzle with compressed air. When the paint material which has high solid contents such as epoxy primer paint is atomized by passing through spray tip nozzle with high pressure, the nozzle composed of tungsten carbide(WC) undergoes the erosive wear, leading to widening of nozzle hole. The deformation of nozzle hole induces improper spray pattern and coating failures such as finger pattern and sagging because the conditions of spray pump pressure and paint flow rate for developing full spray pattern are changed. In this study, an appropriate replacement cycle of spray tip was predicted by measuring the erosive wear tendency as increasing the spraying time of epoxy primer paint.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2830-2844
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• 2012

This review covers recent developments in our group regarding the synthesis, characterization and applications of single-crystalline one-dimensional nanostructures based on a wide range of material systems including noble metals, metal silicides and metal germanides. For the single-crystalline one-dimensional nanostructures growth, we have employed chemical vapor transport approach without using any catalysts, capping reagents, and templates because of its simplicity and wide applicability. Au, Pd, and Pt nanowires are epitaxially grown on various substrates, in which the nanowires grow from seed crystals by the correlations of the geometry and orientation of seed crystals with those of as-grown nanowires. We also present the synthesis of numerous metal silicide and germanide 1D nanostructures. By simply varying reaction conditions, furthermore, nanowires of metastable phase, such as $Fe_5Si_3$ and $Co_3Si$, and composition tuned cobalt silicides (CoSi, $Co_2Si$, $Co_3Si$) and iron germanides ($Fe_{1.3}Ge$ and $Fe_3Ge$) nanowires are synthesized. Such developments can be utilized as advanced platforms or building blocks for a wide range of applications such as plasmonics, sensings, nanoelectronics, and spintronics.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.115-120
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• 2008

There are many typesof accelerometer sensor. There was mainly used high-g accelerometer to obtain data for vehicle in crash test. Accelerometer was mounted on test vehicle with mounting blocks. Test result can be influenced by condition of mounting i.e. bonding material and type of block. These influences can be evaluated to variation of sensitivity in calibration test. In this paper, Calibration test were carried out for 3 types of bonding material i.e. stud, beewax and double side tape. Other factor was taken into consideration by 3-types for mounting block. All test was conducted by sinusoidal signal vibrator up to 4500Hz. In order to investigate influence for sensitivity from different input voltage in the calibrator, the same test was repeated. Test results were compared with standard accelerometer data. Relative sensitivities and phases were showed small difference in sensitivity for bonding materials with one block, but significant one for another block and different input voltage below 1000Hz.

• Special Issue of the Society of Naval Architects of Korea
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• 2008.09a
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• pp.68-75
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• 2008

This paper describes the design and implementation of a low cost inertial navigation system(INS) using an inertial measurement unit(IMU), a digital compass, GPS, and an embedded system. The system has been developed for a transporter that load and unload ship blocks in a shipbuilding yard. When the transporter would move from place to place, they would periodically pass under obstructions that would obscure the GPS signal. This increases the error when estimating the position. Thus the INS has been used to improve position accuracy. INS is also capable of providing continuous estimates of the transporter's position and orientation. Even though IMU is typically very expensive, this INS is made of "low cost" components and the indirect Kalman filtering algorithm.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1357-1371
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• 2024

To investigate the influence of different burial conditions on the seepage characteristics of loose sandstone in the leaching mining of sandstone uranium ore, this study applied different ground pressures and water pressures to rock samples at different burial depths to alter the rock's seepage characteristics. The permeability, pore distribution, and particle distribution characteristic parameters were determined, and the results showed that at the same burial depth, ground pressure had a greater effect on the reduction in permeability than water pressure. The patterns and mechanisms are as follows: under the influence of ground pressure, increasing the burial depth compresses the pores in the rock samples, decreases the proportion of effective permeable pores, and causes particle fragmentation, which blocks pore channels, resulting in a decrease in permeability. Under the influence of water pressure, increasing the burial depth expands the pores but also causes hard clay particles to decompose and block pore channels. As the burial depth increases, the particles eventually decompose completely, and the permeability initially decreases and then increases. In this experiment, the relationships between permeability and the proportion of pores larger than 0.15 ㎛ and the proportion of particles smaller than 59 ㎛ were found to be the most significant.