• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.7
• /
• pp.1326-1331
• /
• 2006

Weld root gap is a important fact of a falling-off weld quality in various kind of weld defect. The welding quality can be controlled by monitoring important parameters, such as, the Arc voltage, welding current and welding speed during the welding process. Welding systems use either a vision sensor or an Arc sensor, both of which are unable to control these parameters directly. Therefore, it is difficult to obtain necessary bead geometry without automatically controlling the welding parameters through the sensors. In this paper we propose a novel approach using neural networks for detecting and monitoring of weld root gap and bead shape. Through experiments we demonstrate that the proposed system can be used for real welding processes. The results demonstrate that the system can efficiently estimate the weld bead shape and detect the welding defects.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.439-439
• /
• 2012

태양광 발전은 발전 셀의 특성상 태양광의 일사량, 태양과 셀 단면이 이루는 각도에 따라서 발전량의 차이를 가져온다. 실리콘 태양전지의 전면 texturing은 입사광의 반사율을 크게 감소시키고, 태양전지 내에서 빛의 통과길이를 증가시켜 태양전지 내의 흡수하는 빛의 양을 증가 시키는 역할을 한다. 따라서 전면 texturing은 단락전류를 증대시키는 효과를 가지고 온다. 일반적으로 texturing은 alkaline etching (WET) 공정과 reactive ion etching (RIE) 공정이 사용된다. 그리고 다결정 실리콘 태양전지의 경우에는 재료의 결정방향에 따라 식각이 되어지는 WET 공정의 경우 texturing 모양을 제어할 수 없어 효과적이지 못하는 결과를 가지고 온다. 본 연구에서는 Electroluminescence을 측정하여 RIE, WET 공정을 사용하여 만든 texturing 구조의 다결정 태양전지의 Microcrack 및 Defect, Electrode Failure, Hot spot등을 검출하였으며, ${\mu}$-PCD 측정 결과와 비교 분석하여 Micro carrier life time을 유추하여 계산하였다. 또한 반사율을 측정해본 결과 WET 공정 대비 RIE의 경우 단파장영역에서 반사율이 크게 감소하여, 상대적으로 높은 External quantum efficiency (EQE)가 측정되었다. 이는 Jsc를 증가시켜, 태양전지의 효율이 증가되는 결과를 얻을 수 있었다.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.12
• /
• pp.1272-1278
• /
• 2012

The micro barrier rip array structures have been applied in a variety of areas including as privacy films, micro heat sinks, touch panel and optical waveguide. The increased aspect ratio (AR) of barrier rip array structures is required in order to increase the efficiency and performance of these products. There are several problems such as burr, defect of surface roughness and deformation and breakage of barrier rip structure with machining high-aspect ratio micro barrier rip array structure using orthogonal cutting method. It is essential to develop technological methods to solve these problems. The optimum machining conditions for machining micro barrier rip array structures having high-aspect ratio were determined according to lengths ($200{\mu}m$ and $600{\mu}m$) and shape angles ($2.89^{\circ}$ and $0^{\circ}$) of diamond tool, overlapped cutting depths ($5{\mu}m$ and $10{\mu}m$), feed rates (100 mm/s) and three machining processes. Based on the optimum machining conditions, micro barrier rib array structures having aspect ratio 30 was machined in this study.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.11
• /
• pp.4950-4955
• /
• 2012

A bolt manufacturing process is completed with continuous forging. Technical and economical success of each process will depend on the appropriate process design and metal mold design for each procedure. This study aims to analyze the moldings of first and second steps among the multi-step molding processes of SCM435 bolt by use of the finite element method in order to achieve the reasonable process. Since the processes of first and second steps analyzed by use of the finite element method consist of axial symmetry, the transformed configuration of material satisfy the dimensions expected in process. In addition, the uniflow line formed in material becomes smooth and consistent over the entire process. Therefore neither molding of material nor inherent defect is expected.

• Korean Journal of Crystallography
• /
• v.3 no.2
• /
• pp.98-110
• /
• 1992

B-SiC thin films were fabricated on Si(100) substrate under 1 atom by fVD. The effects of deposition conditions on the growth and the properties especially crystallinity and prefer ential alignment of these thin films were investigated. SiH4 and CH4 were used as source gases and H2 as Carrier gas. Th9 growth Of B-SiC thin films with changing parameters such as the growth temperature, the ratio of source gases (SiH4/CH4 ) and the total amount of source gases. The grown thin films were characterized by using SEM, a -step, XRD, Raman Spectro- scopy and TEM. Chemical conversion process improved the quality of thin films due to the formation of SiC buffer layer. The crystallinity of SiC thin films was improved when the growth temperature was higher than l150t and the amount of CH4 exceeded that of SiH4. The better crystallinity, the better alignment to the crystalline direction of substates. TEM analyses of the good quality thin films showed that the grain size was bigger at the surface than at the interface and the defect density is not depend on the ratio of the source gases.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.4
• /
• pp.1-11
• /
• 2007

This paper verifies the difference of the seismic behavior and seismic damage of the neighboring two reinforced concrete piers damaged by the 1995 Hyogoken Nanbu earthquake. The two piers were almost the same size, carrying slightly different dead load, and were provided with the same reinforcement arrangement except the amount of longitudinal reinforcement at the bottom portion of the piers. The pier with more reinforcement was completely collapsed due to this near field earthquake by shear failure at the longitudinal reinforcement cut-off while the other was only damaged at the bottom by flexure even though the longitudinal reinforcement cut-off was also existed at the mid height of the pier. According to the results of the pseudo dynamic test, the seismic damage was recognized to be greatly dependent on the ground motion characteristics even though the employed ground motions had the same peak acceleration. The severe damage was observed when the test employed the seismic wave that had strong influence to the longer period range compared to the initial natural period of the pier. On the other hand, based on the similar model experiment, the defect of gas-pressure welded splice of longitudinal reinforcement was revealed to save the piers against collapse due to the so-called fail-safe mechanism contrary to the intuitive opinion of some researchers. It was concluded that the primary cause of the collapse of the pier was the extremely strong intensity and peculiar characteristics of the earthquake motion according to both the site-specific and the structure-specific effects.

• Journal of the Microelectronics and Packaging Society
• /
• v.22 no.4
• /
• pp.99-104
• /
• 2015

The requirement for success of via filling is its ability to fill via holes completely without producing voids or seams. Defect free via filling was obtained by optimizing plating conditions such as current mode, current density and additives. However, byproducts stemming from the breakdown of these organic additives reduce the lifetime of the devices and plating solutions. In this study, the relationship between JGB and current density on the copper via filling was investigated without the addition of other additives to minimize the contamination of copper via. AR 4 with $15{\mu}m$ diameter via were used for this study. The pulse current was used for the electroplating of copper and the current densities were varied from 10 to $20mA/cm^2$ and the concentrations of JGB were varied from 0 to 25 ppm. The map for the JGB concentration and current density was developed. And the optimum conditions for the AR 4 via filling with $15{\mu}m$ diameter were obtained.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.30 no.1
• /
• pp.1-6
• /
• 2020

In this research, 50 nm thick AlN thin films were deposited on the patterned sapphire (0001) substrate by using HVPE (Hydride Vapor Phase Epitaxy) system and then epitaxial layer structure was grown by MOCVD (metal organic chemical vapor deposition). The surface morphology of the AlN buffer layer film was observed by SEM (scanning electron microscopy) and AFM (atomic force microscope), and then the crystal structure of GaN films of the epitaxial layer structure was investigated by HR-XRC (high resolution X-ray rocking curve). The XRD peak intensity of GaN thin film of epitaxial layer structure deposited on AlN buffer layer film and sapphire substrate was rather higher in case of that on PSS than normal sapphire substrate. In AFM surface image, the epitaxial layer structure formed on AlN buffer layer showed rather low pit density and less defect density. In the optical output power, the epitaxial layer structure formed on AlN buffer layer showed very high intensity compared to that of the epitaxial layer structure without AlN thin film.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.58 no.4
• /
• pp.1-8
• /
• 2016

In 2008, 17, 596 dams and reservoirs are scattered across South Korea, and 17, 505 of them (99.5 %) are used for agriculture and 99.3 % are fill dam types. This study aimed to review literature related to the precise safety diagnosis system for agricultural reservoirs established by Korea Rural Community Corporation (KRCC) and analyze problems of its evaluation method. And then, it proposed ways to improve the system including a modified diagnosis system, which was applied to pilot districts in order to verify the utility. For assessment model development of agricultural reservoir, we reviewed status of precision safety inspections systems of agricultural reservoir. There are many problems such as assess agricultural reservoir not by sheet which used in fill dam but by block which used in concrete dam construction and diversion tunnel which main element in reservoir levee is treated as water intake facility. For considering diversion tunnel in reservoir levee, previous precision safety inspection systems which summed in separated phenomenon, separated element, separated site, separated facility was change to new systems which summed in site, phenomenon, element, and facility. Compared results of previous inspection system calculated total assessment index (Ec) with new system calculated total assessment index (Ec) are not show statistical difference.

• Journal of the Korean Wood Science and Technology
• /
• v.36 no.6
• /
• pp.88-95
• /
• 2008

The shrinkage of wood members after construction has been a greater and common concern in wooden buildings with the durability. Particularly, the traditional structure applying solid members actively is easily exposed to the shrinkage that caused by the joints, members, and walls. Moreover, even though domestic larch glulam members are widespread recently in the post-beam construction, the shrinkage (swelling) problem is still the critical defect on the wooden structures by the moisture content change in Korea. Various moisture contents were applied for the specimens to survey the dimensional changes for Japanese larch solid and glulam specimens, and the glulam specimens varied in the number of their laminations. Test results showed that glulam specimens with over 3 bonding layers showed good dimension stabilities. Therefore, to solve the shrinkage problem, sufficient drying fitted to the end-use service conditions should be conducted on the solid or glulam members can be applied.