• Journal of the Society of Naval Architects of Korea
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• v.32 no.2
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• pp.93-102
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• 1995

A series of test was performed by measuring the failure strength and the failure mode of fiber reinforced composite laminates joint containing two holes in Series or Parallel. $[0^{\circ}/45^{\circ}/90^{\circ}/-45^{\circ}]_s$ laminate with W/d(Side distance ratio) 4.0 and E/d(Edge distance ratio) 3.0 has the full bearing strength and are preferable in case of the good efficiency in two series hole. Comparisons were made between testing results and predicting values of the FEM model. Good agreements were fecund between them except the case of $E/d=2{\sim}3$. In the case of $G_h{\geq}3.0d$ and $G_v{\geq}3.0d$ since the interaction coefficients between two parallel holes and between two series holes were small, holes can be treated as independent. The Acoustic Emission(AE) and SEM method were utilized to find out the initial defects, damage and the fracture mechanism.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.247-254
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• 2014

In this study, shear test performed to investigate the shear behavior of flat plate that reinforced by embedded GFRP(glass fiber reinforced polymer) plate with openings. Shape of the GFRP shear reinforcement is a plate with several openings to ensure perfect integration with concrete. The test parameters include the distance between the column face and the first line of GFRP plate and number of GFRP plate vertical strip. The result of test showed that when number of GFRP plate vertical strip was increased, shear strength improved. The shear strength for flat plate reinforced GFRP plate in various codes including ACI 318, BS 8110, EUROCODE 2, and KCI were compared to provide more rational approach for reinforced concrete flat plates with GFRP plate.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.42-47
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• 2002

가. 작업별 시험결과 1) 마늘쪽 분리·선별작업 o 마늘쪽 분리기는 통마늘을 1 또는 2∼3쪽으로 분리하여 1차 선별하고, 마늘쪽 선별기는 분리된 마늘을 3단계로 선별되며 작업성능은 시간당 60접 이상을 분리 및 선별할 수 있다. o 개발된 마늘쪽 분리기와 선별기는 소형 경량이며 취급조작이 편리한 기종하고 작업성능이 높고 손상률이 적어 '01년도에 60대가 농가 보급되었으며 '02년도에는 확대 보급될 전망이다. 2) 파종작업 o 작업성능은 경운기용 파종기 2시간/10a, 승용관리기용 직립파종기는 1시간/10a으로 능률적이었으며 작업정도와 생육상태가 양호하였다. o 지역별 파종작업 체계 -난지형 마늘 파종은 직립파종을 하며 제주, 남해 등은 마늘을 파종한 후 10-11월 줄기가 자랐을 때 무공비닐을 피복하고 줄기를 유인하며, 무안은 유공비닐을 피복하고 구멍에 마늘의 1/2 또는 2/3만 묻히도록 파종하며 별도의 줄기유인 작업은 하지 않는다. 의성지역의 한지형 마늘은 트랙터로 쇄토정지후 보행관리기로 골을 내고 인력으로 마늘을 놓으면 관리기가 다음 골을 내면서 복토하는 체계이다. 3) 마늘 수확작업 -마늘 수확기는 난지형 마늘 수확에는 효과가 적으나, 한지형과 같이 깊게 파종하여 인력으로 뽑기 어려운 재배지역에서는 필요한 기종이며, 토양수분이 많으면 굴취된 마늘과 혼이 진동판에 걸려 작업상태가 불량하므로 마늘과 흙의 이송이 원활토록 진동판 형상 및 적정 진폭 구명이 요구됨 4) 마늘줄기 절단작업 -난지형 마늘은 포장에서 건조후 단기간(1-2주)내에 줄기절단을 해야하므로 기계환가 시급하나 한지형 마늘은 아직도 대부분 줄기를 자르지 않고 묶어서 판매하고 있어 기계화의 시급도는 떨어짐 5) 마늘 선별작업 -마늘선별기는 작업성능이 높고 5등급으로 균일 선별되었으며 손상도 없었으나, 기계가 크고 무거워 이동이 곤란하고 가격이 비싸므로 선별등급을 3∼4단계로 줄이고 소형 농가보급형으로 개량제작이 요구됨. 나. 마늘재배 일관기계화에 의한 노동투하시간과 비용 -종자준비부터 통마늘선별까지의 일관기계화로 투입된 주요작업의 노력은 75∼76%가 절감되고, 재배규모 3ha기준시 비용은 44-53%절감되었음.

• Journal of Drive and Control
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• v.13 no.2
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• pp.34-41
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• 2016

Unlike the commonly used On/Off solenoid, constant attraction force which is independent of plunger displacement is a considerably important characteristic to proportional solenoid of the EPPR Valve. Attraction force uniformity is mainly affected by the internal shape design parameters. Due to a number of shape design parameters, the optimal parameter values are very complex and time consuming to find by trial and error method. Much research has been conducted or are still in progress to find the optimal parameter values by applying various optimization techniques like Genetic Algorithm, Evolution Strategy, Simulated Annealing, or the Taguchi method. In this paper, the design parameters which have primary effects on the attraction force uniformity and the average attraction force are decided by main effects analysis of Design of Experiments. Optimal parameter values are derived using finite-element analysis and a neural network model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.712-721
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• 2017

Recently, the intensity and frequency of floods has increasing worldwide, and flood disasters have become a big problem. Flood disasters, which account for the largest portion of disasters, are floods accompanied by typhoons and localized heavy rainfall. As a result, they cause damage of levee overtopping, in which the water level of a river rises to the levee crown. Therefore, countermeasures are essential and necessary because of the damage to the facility itself as well as to life and other property. The damage magnitude depends on the collapse of the levee. A levee that is difficult to collapse will reduce the discharge inland significantly. Accordingly, the protection of the inland slope, where the collapse of the levee is initiated, is one of the most important countermeasures In this study, revetments with various porosity and forms were suggested and hydraulic experiments were carried out for each type. The hydraulic experiments showed that the stability of a revetment in an inland slope is strongly correlated with the weight per unit area of the revetment. The relationship between the critical velocity, which is the velocity at the moment of leaving the revetment, and the weight per unit area was derived. Through this study, by applying the nature friendly revetment, which has not yet been applied to Korea, it is expected that life and property damage caused by levee overtopping during flooding can be reduced, and a nature friendly river space can be constructed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.543-549
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• 1997

The problems in the existing modeling rules for fishing nets, especially in the Tauti's rule which had been used most commonly, were investigated and it was found that the rules could not give a good similarity between the prototype and model nets because they din neither analyze the flow resistance of nets accurately nor decide the ratio of flow velocity between the two nets properly. Thus, the modeling rule was newly derived by regarding the nets as holey structures sucking water into their mouth and then filtering water through their meshes as in the previous paper. The similarity conditions obtained, between the two nets distinguished by subscript 1 and 2, are as follows; $$\frac{d_2}{d_1}=\sqrt{\frac{l_2}{l_1}},\;\frac{N_2}{N_1}=(\frac{d_1}{d_2})^{1.5}\frac{L_2}{L_1},\;\varphi_1=\varphi_2,\;\frac{d_{r2}}{d_{r1}}=\sqrt{\frac{L_2{(\rho_{r1}-\rho_{w1})}}{{L_1{(\rho_{r2}-\rho_{w2})}}$$ $$\frac{N_{a2}}{N_{a1}}=\frac{W_{a1}}{W_{a2}}(\frac{L_2}{L_1})^2,\;\nu_1=\nu_2\;and\;\frac{R_2}{R_1}=(\frac{L_2}{L_1})^2$$, where L is the length of nettings, d the diameter of netting twines, 2l the mesh size, $2\varphi$ the angle between two adjacent bars, N the number of meshes at the sides of nettings, $d_r$, the diameter of ropes, $\rho_r$, the specific gravity of ropes, $W_a$ the weight in water of one piece of float or sinker, $N_a$ the number of floats or sinkers, $\nu$ the flow velocity, and R the flow resistance of net. In the case where the model experiments aim at investigating the influence of weight in water of nettings on their shapes in nets subjected to the water flow of very low velocity, however, the following condition is added; $$\frac{\rho_2-\rho_{w2}}{\rho_1-\rho_{w1}}=\frac{d_1}{d_2}$$ where $\rho$ is the specific gravity of netting twines.