• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.94-102
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• 2020

Precast concrete segment arch system has an economic and construct ability that combined with advantage of precast concrete and arch behavior. A precast concrete segment arch system with outrigger is consisted of segmented precast panels, a steel outrigger rib, and V-strip to connect precast panels with a steel outrigger rib and cast-in-place anchors in precast panels to connect V-strip should have sufficient pull-out capacity to form its arch shape by site lifting for assembled precast panels and outriggers. However, it is difficult to secure its embedment depth due to the relatively shallow thickness of precast panel. It can be also occurred that flexure deformation of precast panels caused by its pull-out behaviors. In this study, pull-out capacity of cast-in-place anchor was examined for construction of precast concrete segment arch system with outriggers. Therefore, a total of 24 precast panel specimens were fabricated to examine pull-out capacities of cast-in-place anchor in precast panels, and installation depth of anchors, diameter of anchors and wire mesh effects for the precast panel were examined. From this pull-out tests, its pull-out capacities and failure modes were evaluated and the type of the cast-in-place anchor applicable to the precast concrete segment panel arch system with outriggers was determined from comparison of the design specification values.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.539-539
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• 2012

전북대학교 고온플라즈마 응용연구센터는 교육과학기술부 기초연구사업 중 고가연구장비 구축사업의 일환으로, 고 엔탈피, 초음속 유동 환경을 모사하여, 항공우주, 군사기기, 핵융합 분야 등의 고온 재료 개발을 위한 기초 연구 장치로써, 0.4MW급 플라즈마 풍동 장치를 구축하고 있다. 0.4MW 플라즈마 풍동 장치의 플라즈마 발생부는 DC 전원 공급장치와 디스크 형태의 양극과 음극 사이에 동일 형태의 간극을 삽입한 0.4MW급 분절형 아크 플라즈마 토치로 구성되었으며, 토치에서 발생된 아크 플라즈마는 노즐을 통과하며 마하 2~4의 초음속을 나타내도록 설계 제작되었다. 시험 챔버는 노즐에서 나온 초음속 플라즈마의 특성 및 재료 시험을 위한 3차원 이송식 기판이 장착되어 있으며, 고 엔탈피 유동을 관측하기 위한 광학창을 구비하였다. 시험 챔버 하류에는 유동 안정을 위한 디퓨저(diffuser)가 설치되어 있으며, 디퓨저(diffuser)로부터 배출되는 고온가스는 열교환기를 통해 냉각된 후 진공펌프를 통해 대기로 배출되게 된다. 장치의 압력조절을 위하여 $1,000m^3/min$의 용량의 진공펌프 시스템이 설치될 예정이며 가스공급장치, 냉각수 공급장치, 디퓨져, 열교환기는 1MW급 용량으로 설계 제작되었다. 본 장치는 400kW의 전원 공급, 15 g/s의 공기유량 주입 시 약 13 MJ/kg의 고엔탈피를 가진, mach 2~4의 초음속 유동을 나타내는 것을 특징으로 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.139-146
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• 2014

Recently, in field of bridge construction, modular technology has been studied to reduce construction period, traffic impact and environmental impact. This study is a part of research related to the modular bridges. The aim of the study is to analyze the structural behavior and evaluate a serviceability for transverse connection of modular slab bridge. A total of four specimens were fabricated. including a control beam for finding the maximum load by static test. And one control beam and two segmental beams were fabricated for cyclic loading test. As the test result, the beams that were introduced 100% of the design prestressing force showed a smaller maximum deflection, residual deflection and crack width than the control beam. The beam for serviceability evaluation was satisfied with structural serviceability limits of the deflection and crack.

• Journal of Korean Society of Disaster and Security
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• v.16 no.3
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• pp.17-26
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• 2023

Prestressed Concrete (PSC) girders are divided into pre- and post-tension types as prestressing method, and I- and U-type as cross-sectional shape. There are both advantages and disadvantages depending on each prestressing method and cross-sectional shape, and each method is applied to bridge construction sites. In this study, a new girder design was attempted to develop that overcomes its shortcomings by using the pretension method and U-type cross sectional shape. Its structural performance was verified in this study. Pretension type girders are mainly manufactured in factories because they require a reaction arm and related facilities, and have the disadvantage of being limited in weight and span length for road transportation. In addition, in the case of the U-type cross-section, structural stability is very reliable during construction against overturning, but its own weight is relatively large comparing to I-type, and the post-tension method is mainly applied after on-site production. In this study, a PSC girder manufacturing method using the field pretension was proposed and a span length of 40 m real-scale test specimen was manufactured and verified its structural performance.

• The korean journal of orthodontics
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• v.41 no.6
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• pp.384-398
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• 2011

Objective: The purpose of this study was to analyze the stress distribution and the displacement pattern of mandibular anterior teeth under various intrusive force vectors according to the position of orthodontic miniscrews and hooks, using three-dimensional finite element analysis. Methods: A three-dimensional finite element model was constructed to simulate mandibular teeth, periodontal ligament, and alveolar bone. The displacement of individual tooth on three-dimensional planes and the von Mises stress distribution were compared when various intrusion force vectors were applied. Results: Intrusive forces applied to 4 mandibular anterior teeth largely resulted in remarkable labial tipping of the segment according to the miniscrew position. All 6 mandibular anterior teeth were labially tipped and the stress concentrated on the labiogingival area by intrusive force from miniscrews placed mesial to the canine. The distointrusive force vector led to pure intrusion and the stress was evenly distributed in the whole periodontal ligament when the hook was placed between the central and lateral incisors and the miniscrew was placed distal to the canine. Conclusions: Within the limits of this study, it can be concluded that predictable pure intrusion of the 6 anterior teeth segment may be accomplished using miniscrews placed distal to the canine and hooks located between the central and lateral incisors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.965-975
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• 2014

Pretension PSC (Prestressed Concrete) members are subjected to a certain limit of size as they are generally produced in the off-site plant and transferred to the site due to the large scale of the product on system. In this study, a portable pretensioning production system has been developed, which allow us to apply the pretension method on site. Considering that a 50m span PSC girder using the pretension method requires a pressing device to endure a large jacking force, the portable pretension production system has to ensure safety against such a large pretension jacking force. In this study, the portable pretensioning system to produce a 50m span pretension girder was manufactured by using CFT (Concrete Filled steel Tube) members. In order to understand the stability of the system and the behavior of the elements, a static loading test was conducted and the stability of the proposed portable pretensioning production system was confirmed. The developed portable pretension system was applied to several construction sites and was investigated the problems on site. During the pretension girder and slab members that was producted by this pretension system in construction site, it has be found the several advantages such as simple fabrication processes, reduction of prestress-loss, and a decrease of 15% compared with the fabrcation cost of post-tension girder. After due consideration of the problems, this portable pretension system will be improved.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.6.1-6.1
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• 2009

신경외과는 뇌수술과 척추수술로 나눈다. 이중뇌수술 분야에서는 두개강내압 항진시 감압술이라고 '머리의 뚜껑을 연다'라는 표현과 마찬가지로 두개골의 일부분(손바닥크기)을 절제하는 수술이 있다. 이때 과거에는 떼어낸 뼈를 복부의 피하지방밑에 심어서 보관을 하다가 3-6개월 후 환자의 뇌상태가 안정이 되면 다시 꺼내어 제자리에 놓았는데, 골편이 피하지방에서 녹는 경우가 다소 있고, 복부에 이식한 장소가염증이 생기는 경우도 있어서 요즘은 냉동고에서 -70도를 유지하여 보관 후 나중이 복원 수술을 할 때녹여서 사용한다. 이를 '자가골 두개성형술' 이라 한다. 하지만골편의 오염이나 소실 혹은 1차 두개성형술 후 감염 등 어쩔 수 없이 자가골을 사용 못하는 경우에는인공으로 두개골편 모형을 제작하여 '뚜껑'으로 사용해야 한다. 현재PMMA를 이용하여 수술 시 모형을 제작하는 방법이 많이 사용되며 최근 단단한 스펀지 형태의 인공제품이 사용되고 있으나 가격이 매우비싸지만 스펀지 기공내로 자가골이 자란다는 장점이 있다. 척추수술 분야에서는 뼈 대치품을 비교적 많이필요로 한다. 즉 척추 후방고정을 하는 경우 원래 수술의 목적인 감압술이나 교정술 등을 한 후 척추분절간 쇠(티타늄사용)고정을 한 뒤에 뼈조직(자가골이나 동종이식골, DBM, HA stick) 등을 충분히 사용하여덮어줌으로써 분절간 골유합을 유도할 때 많은 양이 필요하며, 척추 전방으로 수술을 하는 경우에도 디스크공간이 빈 상태에서 Cage(추체와 추체를 지지하는 작은 상자모양) 내에뼈조직을 넣어서 척추분절간 골유합이 일어나도록 한다. 최근 HA를 cage 대용품으로 사용한 경우에서 HA가 부서지는 경우가 기사화된바 있다. 또한 경추의 추체 내에 작은 구멍만 뚫고 디스크 수술을 한 후에 그 구멍에 HA+B-TCP 소재를 넣어 천연뼈의 성장 유도를 위해 사용되는 등 신경외과의 다양한 분야에서 생체소재들이 사용되고 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.103-112
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• 2007

The purpose of this study is to evaluate the characteristics of the structural behavior in precast segmental prestressed concrete girders, which consist of five precast segments. These girders were developed to save labor and cost in construction field reducing a term of work. Therefore, four different types of specimens of 25m in length were built, and they were tested and analyzed for observing flexural behavior. The analysis included the investigation of the flexural behaviors in varying tendon amount and at joints using the relationship between moment and deflection. Moreover, nonlinear finite element analysis was utilized to verify the experimental result.

• Korean Journal of Human Ecology
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• v.21 no.3
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• pp.551-565
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• 2012

The primary goal of this study was to provide a systematic methodology of utilizing 3D technology for tight-fit performance sportswear using information of skin deformation in various posture. Technical tools used in this study are Cyberware whole body scanner, RapidForm2004, 2C-AN 3D pattern development program, and YukaCAD. Analysis of the 3D skin deformation while knee joint was bent from $0^{\circ}$ to $60^{\circ}$ revealed that the length of dermatomes L4 was remained consistent during knee bending. Therefore, L4 was chosen as a major cutting line. To develop a highly ergonomic pattern, replicas of static and dynamic postures were developed and integrated using two methods, one is morphing method (Sqirlz Morph), and the other is AutoCAD. Experimental tight-fit garments called 'Derm-Mov Pattern' was designed using dematomes L4, L2, and inner line under knee and compared with four other patterns. As results, AutoCAD was appropriate as a integrating method of various postures. In wear test, 'Derm-Mov Pattern' was rated high (p < .001), in terms of pressure comfort especially around front crotch area. However, wear sensation was not signipicantly different in other area due to highly extensible property of materials. Pressure distribution was relatively even in these experimental garments.

• Research in Plant Disease
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• v.12 no.1
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• pp.62-64
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• 2006

July in 2005, we collected infected maize plant that showing stripe dwarf disease on maize leaf in Jeonbuk provinces including Gochang-gun and conducted genomic dsRNA extraction and RT-PCR. Genomic dsRNA was extracted directly in infected maize plant and electrophoresis in agarose gel. We confirmed 10 segments of genomic dsRNA. We conducted RT-PCR by genomic dsRNA and specific primer of S7, S8 and S10. As a result, specific band of expected size was confirmed respectively. In the results of dsRNA and RT-PCR analysis, we confirmed Rice black-streaked dwarf fijivirus (RBSDV) from naturally infected maize plant. Occurrence of RBSDV of maize plant was dealt 22 ha's damage in maize field. The occurrence rate was 80% in a lot of places of disease.