• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.35-40
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• 2017

A most important progress in civilization was the introduction of mass production. One of main methods for mass production is die-casting molds. Due to the high velocity of the liquid metal, aluminum die-casting is so complex where flow momentum is critical matter in the mold filling process. Actually in complex parts, it is almost impossible to calculate the exact mold filling performance with using experimental knowledge. To manufacture the lightweight automobile bodies, aluminum die-castings play a definitive role in the automotive part industry. Due to this condition in the design procedure, the simulation is becoming more important. Simulation can make a casting system optimal and also elevate the casting quality with less experiment. The most advantage of using simulation programs is the time and cost saving of the casting layout design. For a die casting mold, generally, the casting layout design should be considered based on the relation among injection system, casting condition, gate system, and cooling system. Also, the extent or the location of product defects was differentiated according to the various relations of the above conditions. In this research, in order to optimize the casting layout design of an automotive Oil Pan_BR2E, Computer Aided Engineering (CAE) simulation was performed with three layout designs by using the simulation software (AnyCasting). The simulation results were analyzed and compared carefully in order to apply them into the production die-casting mold. During the filling process with three models, internal porosities caused by air entrapments were predicted and also compared with the modification of the gate system and overflows. With the solidification analysis, internal porosities occurring during the solidification process were predicted and also compared with the modified gate system.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.5
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• pp.73-81
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• 2017

The improved movable weir supplements the advantages and disadvantages of the rubber weir and the conduction gate. It consists of a stainless steel gate, air bags, and a steel clamping plate. The stainless steel gate is the main body of the weir, and the inflatable rubber sheet serves to support the steel gate. The steel clamping plate is typically in direct continuous contact with water, but this leads to corrosion issues that can reduce the life of the entire movable weir. In this study, a panel-type glass-fiber-reinforced polymer (GFRP) clamping plate was designed and fabricated. The test results showed that the flexural load of the panel-type GFRP composite clamping plate was over twice that of the wings type GFRP clamping plate. The lowest moisture absorption value was obtained upon exposure to tap water, and exposure to other solutions showed similar values. Additionally, flexural load testing after exposure to an accelerated environment found the lowest residual loads of 80.51 % and 78.50 % at 50 and 100 days, respectively, for exposure to a $CaCl_2$ solution, while exposure to other environments showed residual failure loads of over 80 % at both 50 and 100 days.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.6
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• pp.390-397
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• 2001

A novel self-aligned ESD (Elevated Source Drain) MOSFET structure which can effectively reduce the GIDL (Gate-Induced Drain Leakage) current is proposed and analyzed. The proposed ESD structure is characterized by sidewall spacer and recessed-channel depth which are determined by dry-etching process. Elevation of the Source/Drain extension region is realized so that the low-activation effect caused by low-energy ion implantation can be avoided. Unlike the conventional LDD structures, it is shown that the GIDL current of the ESD structure is suppressed without sacrificing the maximum driving capability. The main reason for the reduction of GIDL current Is the decreased electric field at the point of the maximum band-to-band tunneling as the peak electric field is shifted toward the drain side.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.903-906
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• 2011

The electroplating and electro-less plating methods have been applied for the high density chip interconnect of the Copper Pillar Tin Bump (CPTB) preparation. The CPTB was prepared, which had been electroplated about $100{\mu}m$ pitch of copper layer firstly, and then the Tin layer was deposited on the copper pillar surface to protect the oxidation of it. It was also very important to get uniform thickness of electroplated copper layer, though it was difficult and sensitive. In order to control the thickness distribution, it was examined that the current separating disk of Insulating Gate with a hole in the center was installed between electrodes. The current flows through the center hole of the Insulating Gate in the cylindrical electroplating bath and the other parts were blocked to protect current flowing. The main current flowed through the center hole of the Insulating Gate directly to the opposite electrode of wafer disk. As the results, it was verified that the copper layer was thick in the center part of wafer disk with distribution of thinner to the outer part toward edge.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.1
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• pp.1-7
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• 2019

In the modern industrial period, the introduction of mass production was most important progress in civilization. Die-casting process is one of main methods for mass production in the modern industry. The aluminum die-casting in the mold filling process is very complicated where flow momentum is the high velocity of the liquid metal. Actually, it is almost impossible in complex parts exactly to figure the mold filling performance out with the experimental knowledge. The aluminum die-castings are important processes in the automotive industry to produce the lightweight automobile bodies. Due to this condition, the simulation is going to be more critical role in the design procedure. Simulation can give the best solution of a casting system and also enhance the casting quality. The cost and time savings of the casting layout design are the most advantage of Computer Aided Engineering (CAE). Generally, the relations of casting conditions such as injection system, gate system, and cooling system should be considered when designing the casting layout. Due to the various relative matters of the above conditions, product defects such as defect extent and location are significantly difference. In this research by using the simulation software (AnyCasting), CAE simulation was conducted with three layout designs to find out the best alternative for the casting layout design of an automotive Oil Pan_BJ3E. In order to apply the simulation results into the production die-casting mold, they were analyzed and compared carefully. Internal porosities which are caused by air entrapments during the filling process were predicted and also the results of three models were compared with the modifications of the gate system and overflows. Internal porosities which are occurred during the solidification process are predicted with the solidification analysis. And also the results of the modified gate system are compared.

• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.353-365
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• 2020

In this study, the characteristics of bed elevation changes of the Nakdong River when weir gates are opened were analyzed using the Hydrologic Engineering Center-River Analysis System (HEC-RAS). The study area was 292.37 km downstream of the Gudam Bridge to the Nakdong estuary of the Nakdong River. The HEC-RAS program, which is a 1D numerical analysis model, was used to simulate bed elevation changes. Simulations were conducted under two scenarios from 2017 to 2019. Scenarios 1 and 2 were devised under the conditions of a fully opened gate and during gate installation, respectively. Results confirmed that, under the conditions of Scenario 1, deposition occurred in most sections from the Hapcheon-Changnyeong weir to the Changnyeong-Haman weir (a distance of approximately 40 km). In addition, it was predicted that the flow that included sediments in the main stream of the Nakdong River was not interrupted by the weir structure and regularly produced changes in the river bed.

• Journal of Power Electronics
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• v.16 no.1
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• pp.74-83
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• 2016

A new family of zero-voltage-transition converters with synchronous rectification is introduced in this study. Soft switching condition for all the converter operating points is provided in the proposed converters. The reverse recovery losses of the rectifier switch body diode are also eliminated. In comparison with the main switch voltage stress, the auxiliary switch voltage stress is reduced significantly. The auxiliary switch does not need the floating gate drive. The auxiliary inductor is coupled with the main converter inductor, and the leakage inductor is used as the resonance inductor. Thus, all inductors of the proposed converter can be implemented on a single core. The other features of the proposed converters include no extra voltage and current stresses on the main converter semiconductor elements. Theoretical analysis for a synchronous buck converter is presented in detail, and the validity of the theoretical analysis is justified with the experimental results of a prototype buck converter with 180 W and 80 V to 30 V.

• Journal of Power Electronics
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• v.12 no.5
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• pp.723-730
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• 2012

This paper presents a new ZVS single phase bridgeless (Power Factor Correction) PFC, using an active clamp to achieve zero-voltage-switching for all main switches and diodes. Since the presented PFC uses a bridgeless rectifier, most of the time, only two semiconductor components are in the main current path, instead of three in conventional single-switch configurations. This property significantly reduces the conduction losses,. Moreover, zero voltage switching removes switching loss of all main switches and diodes. Also, auxiliary switch turns on zero current condition. The presented converter needs just a simple non-isolated gate drive circuitry to drive all switches. The eight stages of each switching period and the design considerations and a control strategy are explained. Finally, the converter operation is verified by simulation and experimental results.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.945-950
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• 2007

The stormwater runoff from paved area are highly polluted because of particulate materials as well as metals from various vehicular activities. The Division of Road Maintenance in Ministry of Construction and Transportation was recently developed the Guidelines of Environment-kindly Road Maintenance. It is actually requiring the BMP construction to control the nonpoint source pollution as based on the TMDL program. This research is carried out in order to define the characteristics of stormwater runoff from the toll-gate of highways since 2006, which is actually one of the main pollutant sources of paved areas. This monitoring is the first phase work for establishing the treatment facilities in the toll-gates. The one of the main characteristics from toll-gate runoff is the first flush phenomenon containing lots of sediments and metal compounds at the beginning of a storm event. Usually it is used to determine the size of treatment facilities and to calculate the reduced pollutant mass in the facility. The research results shows that the mean EMC vaules for heavy metals are determined to $274.3{\mu}g/L$ for Cd, $1,273.4{\mu}g/L$ for Cr, $1,822.0{\mu}g/L$ for Cu, $6,504.9{\mu}g/L$ for Fe, $14,930.3{\mu}g/L$ for Pb, and $714.1{\mu}g/L$ for Zn. Also the metal mass loadings from the toll-gates are calculated using EMC, watershed area and storm duration.

• Journal of Korea Water Resources Association
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• v.31 no.4
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• pp.397-406
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• 1998

The Pyokkolche Reservoir was constructed as a major public project of the ancient agricultural society, 1600 years ago. From a hydraulic point of view, it is considered to have been carried out with a distinguished technology. It should be in particular noticed that for a consecutive banking the main stream was diverted and drained to the Yonpo stream and the dam with same sea levels on its top along the whole length was built in a nearly straight line in spite of the different sea levels between both ends on the bottom. These suggest that the carrying out artifice and surveying technigue of those days were considerably excellent. However, the insufficient plan and design at the time of the construction, the temporary management and the repeated repair works in the later ages caused the Pyokkolche to lose its function. The Changsaenggeo and Kyungjanggeo gate sites being the facilities for sluices composed of a simple span and a vertical lift hand-operated sing a pully. The advantage of the geographical characteristics at both ends of the main dam was scientifically taken to these sites which also functioned as a spillway against a flood. The gate site of Suyogeo must have been located in an entrance to Suwolri, the northern end of the Pyokkolche and Yutonggeo is presumed to have been located on the right of Sangsori, the southern end of the Pyokklche. Keywords : Pyokkolche Reservoir, construction technology, gate site location.