• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.3
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• pp.186-193
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• 2018

Modern manufacturing industries is to produce both precise and robust mechanical parts without failure while they are in service. In order to prevent a part failure for its lifetime, a mechanical design for a part should be examined on a basis of mechanical simulation. A nozzle plate, being a key part in steam engines, changes flow directions of steam in a turbine used in power plant. This paper is to the design and test for part safety and durability. Currently, nozzle plates are fabricated by welding nozzles to their plates. Welding causes some defects on the used materials while they are being manufactured. Another major defect is un-even pitches between welded nozzles. Welding causes phase changes because of high melting temperature of metal. This leads to decay on the welding spots, which weakens their structural strength and then, may lead to early damages on mechanical structures. This research proposes assembly-typed nozzle plate without welding. From the beginning, nozzle and plate are designed for insertion-typed assembly. Nozzle head and foot are designed in accordance with the grooves on outer ring and inner ring of a plate to make mating surfaces. Then the nozzle plate should be proved for structural and fatigue safety before they are put in manufacturing. This research adopts commercial softwares for modeling and mechanical simulation. The test result shows that the design with smaller mating area and deeper insertion produces higher safety in terms of structure and durability. From the conclusion, this paper proposes the assembly-typed nozzle plate to replace the welding typed.

• Journal of Hydrogen and New Energy
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• v.23 no.5
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• pp.468-475
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• 2012

A proper stacking force and assembly are important to the performance of fuel cell. Improper assembly pressure may lead to leakage of fuels and high interfacial contact resistance, excessive assembly pressure may result in damage to the gas diffusion layer and other components. The pressure distribution of gas diffusion layer is important to make interfacial contact resistance less for stack performance. To analyze the influence of design parameter factors for pressure distribution, and to optimize stack design, DOE (Design of Experiment) was used for polymer electrolyte membrane fuel cell stack pressure test. As commonly known, the higher clamping force improves the fuel cell stack performance. However, non-uniformity of stress distribution is also increased. It shows that optimization between clamping force and stress distribution is needed for well designed structure of fuel cell stack. In this study, stack design optimization method is suggested by using FEM (Finite Element Methode) and DOE for light-weighted fuel cell stack.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1095-1101
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• 2012

This paper presents a design of a BLDC servo motor control system for the auto process of assembly and supply using DSP(Digital Signal Processor) controller and IGBT driver. The assembly and supply auto processing system needs torque, speed, position control of servo motor for variable action. This paper implements those servo control with vector control and space vector PWM(Pulse Width Modulation) technique. As CPU of controller, TMS320F240 DSP was adopted because it has PWM waveform generator, A/D converter, SPI(Serial Peripheral Interface) port and many input/output port etc. This control system consists of 3-level hierarchy structure that main host PC manages three sub DSP system which transfer downward command and are monitoring the states of end servo controllers. Each sub DSP system operates eight BLDC servo controllers which control BLDC motor using DSP and IPM. Between host system and sub DSP communicate with RS-422, between main processor and controller communicate with SPI port.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.597-608
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• 2021

The control head components used in small military vessels are designed to be domestically produced, prototypes, structural analysis, and casting methods are designed and cast. The control head assembly consists of a lever, an aluminum outside cover, Middle, front gear cover, back gear cover, and a zinc worm gear. In order to reverse the design of each component, 3D scanning device was used, 3D modeling was performed by CATIA, and prototype productions were carried out by 3D printer. In order to reduce the cost of components, gating system is used by gravity casting method. The SRG ratio of 1:0.9:0.6 was set by applying non-pressurized gating system to aluminum parts, 1:2.2:2.0 and pressurized gating system to zinc parts, and the shapes of sprue, runner and gate were designed. The results of porosity were also confirmed by casting analysis in order to determine whether the appropriate gating system can be designed. The results showed that all parts started solidification after filling completely. ANSYS was used for structural analysis, and the results confirmed that all five components had a safety factor of 15 more. All castings are free of defects in appearance, and CT results show only very small porosity. ZnDC1 zinc alloy worm gear has a tensile strength of 285 MPa and an elongation of 8%. The tensile strength of the four components of A356 aluminum alloy is about 137-162 MPa and the elongation is 4.8-6.5%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.3
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• pp.40-46
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• 2021

An automatic transmission of automobiles enables comfortable driving experience with lower transmission shifting jerks. However, the assembly structure is more complicated and requires additional components with lower efficiency than the manual transmission system. Extensive research has been conducted to improve the overall transmission efficiency by optimizing each component of the automatic transmission assembly. This study focuses on enhancing the friction torque of double angular contact ball bearings used in automatic transmission. The friction torque of the bearing varies with the operating conditions such as the operational load and rotating speed. Since reducing the friction torque of the bearing tends to deteriorate the durability of the bearing, it is necessary to design the bearing having a minimum required friction torque by determining the durability life of an automatic transmission assembly, In this study, the theoretical life and friction torque of conventional and newly-developed bearings are calculated. The difference in the friction torque between the new and existing bearings are also evaluated.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.210-210
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• 2022

Silybum marianum is an annual or biennial plant from the Asteraceae family. It can grow in low-nutrient soil and drought conditions, making it easy to cultivate. From the seed, a specialized plant metabolite called silymarin (flavonolignan complex) is produced and is known to alleviate the liver from hepatitis and toxins damages. To infer the phylogenetic placement of a Korean milk thistle, we conducted a chloroplast assembly and annotation following by a comparison with existing Chinese reference genome (NC_028027). The chloroplast genome structure was highly similar with an assembly size of 152,642 bp, an 153,202 bp for Korean and Chinese milk thistle respectively. Moreover, there were similarities at the gene level, coding sequence (n = 82), transfer RNA (n = 31) and ribosomal RNA (n = 4). From all coding sequences gene set, the phylogenetic tree inference placed the Korean cultivar into the milk thistle clade; corroborating the expected tree. Moreover, an investigation the tree based only on the ycf1 gene confirmed the same tree; suggesting that ycf1 gene is a potential marker for DNA barcoding and population diversity study in milk thistle genus. Overall, the provided data represents a valuable resource for population genomics and species-centered determination since several species have been reported in the Silybum genus.

• Journal of the Korean Society of Clothing and Textiles
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• v.48 no.2
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• pp.312-327
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• 2024

In this study, a rehabilitation 3D printed wearable device was developed by combining an assembly-type robot hand and an integral-type robot hand through fused deposition 3D printing manufacturing with various hardness TPU (Thermoplastic Polyurethane) filaments. The hardware configuration of the robot hand includes a controller designed with four motors, one small servo motor, and a circuit board. In the case of the assembly-type robot hand model, a 3D printed robot hand was assembled using samples printed with TPU of hardness 87A and 95A. It was observed that TPU with a hardness of 95A was suitable for use due to shape stability. For the integrated-type robot hand model, the external sample using TPU of hardness 95A could be modified through a cutting method, and the hardware configuration is the same as the assembly-type. The system structure of the 3D printed robot hand was improved from an individual control method to a simultaneous transmission method.Furthermore, the system architecture of an integrated 3D printed robotic hand rehabilitation device and the application of the rehabilitation device were developed.

• BMB Reports
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• v.49 no.12
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• pp.653-654
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• 2016

The human reference genome, maintained by the Genome Reference Consortium, is conceivably the most complete genome assembly ever, since its first construction. It has continually been improved by incorporating corrections made to the previous assemblies, thanks to various technological advances. Many currently-ongoing population sequencing projects have been based on this reference genome, heightening hopes of the development of useful medical applications of genomic information, thanks to the recent maturation of high-throughput sequencing technologies. However, just one reference genome does not fit all the populations across the globe, because of the large diversity in genomic structures and technical limitations inherent to short read sequencing methods. The recent success in de novo construction of the highly contiguous Asian diploid genome AK1, by combining single molecule technologies with routine sequencing data without resorting to traditional clone-by-clone sequencing and physical mapping, reveals the nature of genomic structure variation by detecting thousands of novel structural variations and by finally filling in some of the prior gaps which had persistently remained in the current human reference genome. Now it is expected that the AK1 genome, soon to be paired with more upcoming de novo assembled genomes, will provide a chance to explore what it is really like to use ancestry-specific reference genomes instead of hg19/hg38 for population genomics. This is a major step towards the furthering of genetically-based precision medicine.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.439-449
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• 2002

This paper reviews our recent research works on the interconnection technologies in electronic packaging and assembly. At the aspect of advanced joining methods, laser-ultrasonic fluxless soldering technology was proposed. The characteristic of this technology is that the oxide film was removed through the vibration excitated by high frequency laser change in the molten solder droplet. Application researches of laser soldering technology on solder bumping of BGA packages were carried out. Furthermore, interfacial reaction between SnPb eutectic solder and Au/Ni/Cu pad during laser reflow was analyzed. At the aspect of soldered joints' reliability, the system for predicting and analyzing SMT solder joint shape and reliability(PSAR) has been designed. Optimization design method of soldered joints' structure was brought forward after the investigation of fatigue failure of RC chip devices and BGA packages under temperature cyclic conditions with FEM analysis and experimental study. At the aspect of solder alloy design, alloy design method based on quantum was proposed. The macroproperties such as melting point, wettability and strength were described by the electron parameters. In this way, a great deal of the experimental investigations was replaced, so as to realize the design and research of any kinds of solder alloys with low cost and high efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.918-921
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• 2003

The electrochemical behavior of vilogen self-assembled monolayer has been investigated with QCM, which has been known as ng order mass detector. The self-assembly process of viologen was monitored using resonant frequency(${\Delta}F$) and resonant resistance(R). The QCM measurements indicated a mass adsorption for viologen assembling on the gold surface with a frequency change about 300, 135 Hz and calculated its surface coverage($\Gamma$) to be $5.02{\times}10^{-9}$ and $1.64{\times}10^{-9}mol/cm^2$. Also a reversible redox process was observed and analyzed with an ionic interaction at the Viologen/solution interface using ${\Delta}F$.