Due to stricter environmental regulations of the International Maritime Organization (IMO), the number of ships fueled by Liquefied Natural Gas (LNG) is rapidly increasing. The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) limits the material of tanks that can store cryogenic substances such as LNG. Among the materials listed in the IGC Code, ASTM A553M-17 has been recently adopted as a material for LNG fuel tank projects because of its excellent mechanical properties at cryogenic temperatures. In shipyards, this material is being used to build tanks through Flux Cored Arc Welding (FCAW). However, there is a problem that magnetization occurs during welding and there is a big difference in welding quality depending on the welding position. In order to overcome this problem, this study intends to conduct basic research to apply laser welding to ASTM A553M-17 material. In Part I, the bead shape according to the welding output was analyzed and in PART II, ​​the penetration phenomenon according to the welding speed was analyzed after Bead on Plate (BOP) test. As a result of analyzing the bead shape according to laser power performed in this study, it was confirmed that the laser power and penetration depth are proportional to some extent. In addition, a range of suitable welding power was proposed for the 6.1mm thickness material performed in this study.

Because of the International Maritime Organization(IMO)'s regulation to regulate emissions of ships, a change is taking place to replace ship fuels from Heavy Fule Oil(HFO) to Liquefied Natural Gas(LNG). In the case of LNG, it is a material obtained by liquefying Natural Gas(NG), and it is -163 degrees below zero, and the volume is reduced to 1/600 level. The material of the tank that can store LNG must be a material that can safely store LNG in a cryogenic environment, and the materials of the tank that can store LNG are limited in the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk(IGC Code). Among the materials listed in the IGC Code, 9% nickel steel is used as a material for LNG fuel propulsion tanks that are recently ordered because of relatively high mechanical properties under cryogenic environments. In this study, the mechanical properties of butt welds were measured following the weld reliability evaluation of Flux Cored Arc Welding(FCAW) butt welds made of 9% nickel steel by PARTI. The measured mechanical properties are tensile strength, bending strength, hardness, and cryogenic impact test required by the classification for Welding Procedure Specification(WPS) approval.

Because of the International Maritime Organization(IMO)'s regulation to regulate emissions of ships, a change is taking place to replace ship fuels from Heavy Fule Oil(HFO) to Liquefied Natural Gas(LNG). In the case of LNG, it is a material obtained by liquefying Natural Gas(NG), and it is -163 degrees below zero, and the volume is reduced to 1/600 level. The material of the tank that can store LNG must be a material that can safely store LNG in a cryogenic environment, and the materials of the tank that can store LNG are limited in the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk(IGC Code). Among the materials listed in the IGC Code, 9% nickel steel is used as a material for LNG fuel propulsion tanks that are recently ordered because of relatively high mechanical properties under cryogenic environments. In this study, butt welding was performed on a 9% nickel steel material using Flux Cored Arc Welding(FCAW), the most widely used welding method in shipyards. In PARTI, after securing the welding conditions, cross-sectional observation results analysis, liquid penetrating test, and radiographic test were performed to verify the reliability of the weld.

This study was conducted to compare the mechanical properties of NAB (Ni-Al-Bronze) material manufactured using WAAM (wire arc additive manufacturing) technology and cast NAB that has been used. Two types of mechanical property test pieces were collected from the deposited bulk NAB material according to the direction of deposition, and compared with each other. As a result of mechanical property evaluation, the deposited NAB exhibited anisotropy according to the direction of deposition, and showed high tensile strength, hardness, and shock absorption in the longitudinal direction of the welding line.

Spot welding is a representative process in automotive welding and the application of intelligent systems is accelerating. In particular, in the case of welding electrode management, the timing of electrode wear and dressing was determined by continuous spot welding evaluation, however there is concerned that errors in welding equipment or processes may work in a complex manner. In this study, a dynamic resistance waveform sensing and image measurement system that greatly affects the nugget formation, which is important to the quality of spot welding, was fabricated and used. Based on the experimental data of the galvanized steel sheet, an electrode life prediction algorithm for electrode wear was derived through CNN(Convolutional Neural Network) model of machine learning training.

본 연구의 목적은 배드민턴 여자 중학생 전문선수(10명)와 방과 후 배드민턴 수업에 참여하는 일반학생(10명)의 하이클리어 동작 시 COM과 COP의 수평거리, 그리고 COM과 COP의 이동패턴의 차이를 비교 분석하는데 있다. 두 그룹 간 하이클리어 스트로크 이후 착지 시점(E4)에서 COM과 COP의 X 축과 Y축에서의 수평거리와 백스윙, 포워드스윙, 스윙전체의 X축, Y축, 그리고 Z축에서 COM의 최대이 동범위의 차이를 비교하기 위해 독립표본 T-test를 실시한 결과, 첫째, 하이클리어 스트로크 임팩트 이후 착지 시점(E4)에서 여자 중학생 전문선수는 전후방향(X축)에서 COM와 COP지점이 일반학생에 비해 매 우 가깝게 위치하였다. 둘째, 전문선수는 COM의 수직움직임, 일반선수는 COM의 수평움직임을 적극적으로 활용하였다.

As the part of efforts to respond to the environmental pollution, the demand for clean energy is increasing. Natural gas is one of the most realistic alternatives, and interest in the storage and transportation containers to utilize the natural gas is growing. The production area of ​​natural gas is limited, and in Korea, it is imported in the form of liquefied natural gas. LNG is a cryogenic state with a vaporization point of -163°C, so the ordinary metal cannot be used due to its brittleness. The international maritime organization (IMO) defines the metals that can handle LNG in the IGC Code, and the research is ongoing. This study was a preliminary study to check the weldability of related metals and confirmed the shape of bead on plate (BOP) during the laser welding for each material. In part I, a study was conducted on the high manganese steel, and in part II, a study was conducted on the materials of STS304L and STS316L among the stainless steel. Based on this study, it can be used as an optimal welding condition for the butt and fillet welding.

As demand for eco-friendly energy increases, demand for natural gas and Liquefied natural gas (LNG) storage technologies continues to increase. LNG is a cryogenic environment with a temperature of -163°C, so ordinary metals cannot be used due to brittleness. Accordingly, IGC Code designates the cryogenic materials such as Invar, STS304L, Al5083-0, and High Manganese Steel. For fabricating those materials, research on welding possibility is the most important. Thus this study focused on the possibility of laser welding of the cryogenic materials. The weldability of High Manganese Steel was researched in this paper, the shape and the dimensions of the beads after bead on plate (BOP) welding were observed. The experiment was conducted on a total of 25 cases with laser power and welding speed of 5 cases each, and the width, height, and penetration of the beads were confirmed. It was confirmed that the paramenter of bead increased linearly with the laser power, and the paramenters of bead increased linearly with decreasing welding speed. Based on this study, high manganese steel can be applied in various industries by applying it to butt welding.

In this study, the deformation of friction stir welding on the aluminum battery housing material(AL6063-T5) applied to the electric vehicle was effectively predicted through experiments and numerical simulations. The temperature data were measured during the friction stir welding experiment, and the numerical simulation was carried out using the experimental temperature data. In the heat transfer analysis, the temperature distribution of the structure over time was calculated using the Reynolds equation. The final friction stir welding deformation was calculated by performing the structural analysis using the calculated temperature distribution data over time. The thermal elasto-plastic analysis was performed according to the friction stir welding process conditions and the welding sequences. Finally, the optimum welding condition was derived that the welding speed is 1000 mm/min and the rotation speed of the tool is 2000 RPM.

The verification and the design improvement of weight-training machines were performed. This research was carried out with computer simulation using the musculoskeletal model of the human body. The main topic of this research is the improvement of an arm-curl machine. Also the improved exercise effects were observed in this paper. The existing exercise which moves the scapula on the axis of the elbow with raised forearm is effective for only Biceps. We suggested the new concept arm-curl machine that also raises the scapula after raising the forearm to be effective for Triceps and adjacent muscles. The exercise effect to the Biceps and Triceps was verified in the partⅠ, that to the non-adjacent muscle such as Lattismus Dorsi was verified in the partⅡ of this study. The analysis with computer simulation using the musculoskeletal model could be helpful to develop improved healthcare machines with reduced price and time.

Contemporary people want to develop their bodies to enhance quality of life. Although weight-training machines have been mainly developed with this trend based on intuition and experience, this study attempted to improve and verify those products through computer simulations using the musculoskeletal model of the human body. An arm-curl machine, a weight-training machine for arm exercise, was chosen for this research and the improved exercise effects were observed. The existing exercise that moves the scapula on the axis of the elbow with raised forearm is effective for biceps but not for triceps and adjacent muscles. Thus we suggested the idea for a new concept arm-curl machine that also raises the scapula after raising the forearm. To verify the effects of this new exercise, we manufactured arm-curl linkage. The experiments found that the exercise effects of the biceps were maintained, and the exercise effects of the triceps remarkably improved. These findings verified the effects of the proposed new concept arm-curl linkage.

본 연구는 우리나라 흑비둘기 최대 서식지인 울릉도에서 2016년 3월부터 2018년 2월까지 흑비둘기의 지역별 개체군 변동과 선호하는 생태적 환경에 대하여 조사하였다. 조사기간 동안 40개 정점에서 확인 된 흑비둘기의 누적개체수는 1,956개체가 조사되었고 최대개체수는 2016년 8월에 326개체가 출현하였다. 월별 개체수 변동은 10월부터 출현개체수가 감소하다가 겨울철인 12월에서 2월에는 거의 관찰되지 않았다. 지역별 개체수 비율은 2016년에는 나리분지 지역이 33.43%로 가장 높았고 2017년에는 태하, 학포 지역이 29.39%로 흑비둘기가 많이 출현하였다. 흑비둘기가 선호하는 서식지 특성은 활엽수림 (77.5%), 임분의 영급은 4영급(75%), 흉고직경(DBH)은 중경목(80%), 수관수밀도는 밀밀도를 선호하였다. 해발고는 평균 178.22±36.60 m(SD, n=40, range 10∼472)였고 10∼160 m 지역이 전체 지역의 57.5%를 차지하여 저지대 산림을 선호하는 것으로 나타났다.

As a part of the research on existing structures of private homes from Joseon Era. Focusing on one hundred twenty five-purlin houses, the current study investigated the features and characteristics of the house structure from style, size, proportion and roof pitch, and measurements of key parts, and developed the following conclusions. Most are single-houses (89, 83%), and among them, there are 47 single front-terrace houses (39%), which is the highest number. The sizes of lower house structure do not differ greatly depending on the vertical structure, and single rear terrace house and double-house have relatively larger side sizes. The size of upper structure is larger in double-houses compared to other vertical structures, indicating a relatively higher roof. The cross-section measurement of major parts show that double-houses are larger than single-houses by 3cm in pillar, 3-4.5cm in crossbeam length, and 4.5cm in crossbeam width. However, Janghyeo width was consistent at 7.5 to 10.5cm, maintaining uniformity regardless of vertical structure of the houses. In addition, the cross-section measurements decreased from sixteenth to nineteenth century, with the size of pillar size decreasing the most. The result that the Janghyeo width is not related to the house structure house confirmed that the Janghyeo width was kept consistent regardless of the size of the house structure.

최근 들어 비행정보에 대한 확인기술의 발달과 소형 드론의 지속적인 기술개발로 인하여 이동성과 안정성이 확보된 근접 항공촬영이 가능해졌다. 특히 GPS좌표를 활용하여 경로비행의 위치를 직접 지정함으로써 조사대상지에 대한 경 로비행의 정확성과 안정성이 확보되었으며, 이를 통해 일정한 고도를 유지한 상태에서 정사투영 촬영을 통한 분석이 가능하게 되었다. 따라서 본 연구에서는 수목의 생육관리와 3D맵핑 시스템의 접목에 착안하여 정밀하고 체계적인 3D 맵핑 도면작성을 활용하여 수목의 시공과 관리측면에서 경제적이고 장기적인 차원에서 수목의 상태를 파악하기 위한 방안을 모색하고자 하였다. 특히 문화재로 지정된 수목의 경우처럼 고부가가치를 지닌 수목에는 활용도가 더 크다 하겠다. 항공사진 촬영에 이용된 UAV는 Mikrokopter사의 회전 익을 이용하였으며, 디지털 데이터의 취득은 Sony α5100을 활용하였다. 항공사진촬영 시 공간해상도를 고려하여 비행고도를 설정하였는데, 계획된 공간해상도 3Cm를 확보하기 위해 비행고도는 대상지를 기준으로 80m로 설정하였으며 촬영 시 종중복율(Endlap) 및 횡중복율(Sidelap)을 45%로 설정하여 항공사진촬영을 실시하였다. 그 결과 약 4개의 스트립 비행 경로를 따라 44개의 Waypoint가 설정되었으며, 비행고도와 속도는 80m, 약 3m/sec로 항공사진촬영을 실시하였다. 연구대상지인 광한루원의 항공사진 촬영을 결과를 살펴 보면 44개의 Wapoint 중 41개 지점에서 촬영되었으며, 취득된 디지털데이터에 비행로그데이터를 적용하여 잔차분 석을 통한 유효성을 검증한 결과 UAV에서 촬영된 41개의 디지털데이터 모두 유효한 데이터로 확인되었다. 3D맵핑 데이터제작 및 DEM분석은 Photoscan을 이용하 여 데이터를 추출하였다. 3D맵핑을 위한 데이터의 정합은 UAV 시스템에서 취득된 디지털영상데이터를 모두 이용하였으며, Photoscan의 자동영상매칭 기능을 이용하여 Point Cloud Data 형식의 데이터를 하나의 데이터로 정렬한 후 이를 바탕으로 Polygon Data 및 Texture로 변환하여 약4.5 ㎝급의 DSM을 생성하였으며, 정사투영 방식의 보정을 통해 약 3cm급의 정사영상데이터를 제작하였다. 취득된 디지털데이터를 통해 구축된 공간정보데이터의 보정 및 정확성 검토를 위해 UAV를 이용하여 취득된 영상과 GPS/INS데이터, 기상기준점 측정 데이터를 기반으로 정확성을 검토하였다. 지상기준점측량은 RTK(Real Time Kinematic)의 GRS80좌표 시스템을 이용하여 데이터를 취득하였으며, 측량지점은 3곳을 지상기준점으로 선정하였 다. 측정결과 RMSE는 ±5Cm 이내의 정확성을 가지는 것으 로 나타나 정사영상 데이터를 이용한 수목의 수관폭 등에 대한 평면데이터 구축에는 문제가 없는 것으로 파악되었다. 구축된 정사영상 데이터를 분석한 결과 총 25주의(산수 유4, 은행나무7, 소나무9, 단풍나무4, 모과나무1) 수목이 확인되었는데, 이중 산수유와 은행나무는 현장조사를 통해 수목의 종류를 확인하였다. 정사영상 데이터를 바탕으로 최종 생성된 DSM데이터를 살펴보면, 시설물 및 지형에 대한 수치데이터는 정확하게 분석되었으나 수목의 경우에는 총 25주의 수목중 약 50%에 해당하는 12주(단풍나무 3주, 소나무 5주, 산수유 4주)의수목에 대한 3D데이터가 추출되었다. 이러한 이유는 항공촬영을 통한 디지털데이터 구축에 있어 수직부감으로 촬영된 디지털데이터는 수목의 불규칙면에 대한 데이터 구축의 어려움과 수목 일부가 그림자와 중첩됨으로써 그림자로 인식되는 현상, 수목들 중첩되는 구간에 대한 3D데이터 구축이 어려운 것으로 판단되었으며 최근에 식재된 수목(은행나무(7)에서 3D데이터가 생성되지 않는 것으로 나타났다. 따라서 추후 항공촬영에 있어 디지 털 데이터 구축 시 45도 사선 촬영을 포함하여 항공사진촬 영 시간과 시기 등에 대한 보완이 필요할 것으로 판단되며, 3D데이터 구축에 필요한 위치좌표의 참고자료 구축을 위해 다양한 고도에서 항공사진촬영을 실시함과 동시에 지상 촬 영의 병행을 통해 수목개체군에 대한 종합적인 3D데이터 구축이 가능할 것으로 판단된다.