Demand for research on the use of hydrogen, an eco-friendly fuel, is rapidly increasing in accordance with global environmental problems and IMO environmental regulations in the shipbuilding and marine industry. In the case of hydrogen, similar to liquefied natural gas, it has a characteristic that its volume decreases hundreds of times during phase transformation from gas to liquid, so it must be stored in a tank in the form of liquefied hydrogen for transport efficiency. The material of the liquid hydrogen tank is selected in consideration of mechanical properties and hydrogen embrittlement at cryogenic temperatures. In this study, welding research was conducted on STS316L material, which was most commonly used in the space industry. In this study, flux cored arc welding was performed under 4 welding conditions to derive the optimal welding conditions for STS316L material, and then mechanical properties of the welded part were compared and analyzed.

A heat exchanger refers to a pressure vessel that indirectly exchanges heat between low-temperature/ high-temperature fluids with a solid wall interposed therebetween, and a shell-and-tube cylindrical heat exchanger is generally applied. The shell-and-tube cylindrical heat exchanger is widely used in ships and there is a problem in that the welding area is narrow and welding defects occur a lot due to high-level welding. In particular, in the case of a ship heat exchanger, if a problem occurs in the welding part during operation, the possibility of a safety accident is high, and repair is not easy. In this study, to solve this problem, the GTAW(Gas Tungsten Arc Welding) method was applied to secure the optimum conditions for pipe welding of STS304 material with a thickness of 5.5mm and to conduct a test. Afterwards, in accordance with the ASME rules, welding performance was verified through cross-sectional observation of welds, mechanical property tests, (tensile strength, bending strength, cryogenic impact strength) and non-destructive testing(PT, RT).

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.

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.

Light weighting is one of techniques considered importantly at designing the mechanical structure using the light weight material. This study deals with aluminum-6061 and aluminum foam which stood in the spotlight of light weight material. And the finite element method for safety evaluation has been carried out in order to prevent from the damage and fatigue fracture due to crack appearing at the mechanical structure with this material. The simulation analysis as MT(middle tension) test was carried out by using the core of aluminum foam and the material laminated with sandwich structure of Al-6061. The mechanical structure is linked together with various parts and designed as the material with hole or crack. So, MT test is one of the test methods to evaluate the fatigue fracture characteristic of material and the strength inside material with the center crack by applying the load to the part connected pin. The real material strength is thought to be evaluated through the study result of MT test analysis.

Al2O3-SiC ceramic composites are produced using pressureless sintering, and their plasma resistance, electrical resistance, and mechanical properties are evaluated to confirm their applicability as electrostatic-discharge-safe components for semiconductor devices. Through the addition of Mg and Y nitrate sintering aids, it is confirmed that even if SiC content exceeded 10%, complete densification is possible by pressureless sintering. By the uniform distribution of SiC, the total grain growth is suppressed to about 1 μm; thus an Al2O3-SiC sintered body with a high strength over 600 MPa is obtained. The optimum amount of SiC to satisfy all the desired properties of electrostatic-discharge-safe ceramic components is obtained by finding the correlation between the plasma resistance and the electrical resistivity as a function of SiC amount.

Three-dimensional motion analysis systems and force plates are used for gait phase detection and ground reaction force(GRF) or ground reaction moment(GRM) data collection. But force plates as measurement systems are restricted to laboratory environments and have limitations for abnormal walking with foot dragging. Therefore the methods were proposed to compute the GRM from the kinematic data of three-dimensional motion analysis systems. Gait phase detection with kinematic data using foot velocity algorithm(FVA) was performed. The validity of gait phase detection was obtained comparing with the results of force plates. A gait model with 7 segments was composed to compute GRM. The results of gait model with kinematic data were compared with those of force plates. The result of the vertical direction is similar. But anterior-posterior direction and lateral direction show similar tendency with some gaps.

벗초파리(Drosophila suzukii)는 아시아가 원산인 파리목 초파리과의 해충이다. 국내에서의 피해사례는 보고되지 않았지만 북미와 유럽에서는 블루베리, 체리, 포도 등의 작물에 많은 피해를 입히는 중요한 해충으로, 알자스의 포도 수확량이 15% 정도 감소되었다는 피해사례가 보고되었다. 미국, 뉴질랜드 등에 수출을 할 때 검역 해충으로 수출포도단지 및 선과장 등에서의 발생이 민감한 해충이다. 본 연구는 효율적인 초파리 모니터링을 위해 식초의 종류, 식초량에 따른 유인량을 알아보고, 수출포도단지에서의 벗초파리 발생시기를 알아보고자 수행하였다. 사과 식초 30, 70, 100ml를 넣고 초파리 유인량을 비교한 결과 유인량에는 차이가 없었다. 양조식초, 현미식초, 사과식초, 백포도식초, 사과식초+와인(5:5) 처리 결과 사과식초+와인(5:5)에서 유인량이 가장 많았다. 수출포도단지 내 재배포장에서 조사한 결과 노랑초파리는 8월에도 발견되었으나, 벗초파리는 9월 중순부터 발견되었다.

가루깍지벌레(Pseudococcus comstocki)는 노린재목 가루깍지벌레과로 포도원에서 나무껍질 사이에 알, 약충 및 성충으로 월동하고, 봄철 포도나무 수액이 이동할 즈음 활동을 시작한다. 개체수가 증가하는 7월 중순에 이동을 시작해 결과지와 봉지를 씌운 포도송이 안에서 줄기를 흡즙하고 감로를 배설하여 그을음병을 유발한다, 7월 하순~8월 상순 경에 포도 과실 지경에 알을 낳으며, 포도 수확기인 9월 상순 무렵 약충이 증가되면 그을음이 늘어 포도 상품성을 떨어뜨린다. 유기포도원의 알렉산드리아 같은 청포도 계통의 포도에서는 피해 증상이 뚜렷이 나타나 농가피해가 더욱 심하다. 본 연구는 가루깍지벌레의 피해를 줄이고자 식물로부터 유래하는 기피물질을 이용해 시설포도원에 적용하고자 수행하였다. 선발된 essential oils을 6월부터 8월까지 포도송이 줄기와 만나는 T자 줄기에 털실을 감고 0∼100㎕ 처리한 결과 100㎕ 처리시 기피효과가 높았으며, 6월부터 8월까지 처리한 결과 7월 중․하순에 처리하였을 때 기피효과가 가장 높게 나타났다.

At modern mechanical and automotive industry, the material with light weight proceeds in order to thr environmental issue and high performance. Machine part is fastened with numbers of bolts and nuts. Generally, the metal part at mechanical structure is fastened with bolt and nut through puncturing. But it is difficult to puncture at CFRP with the property of fiber structure like the general metal. In this study, the fracture behavior is investigated by the hole and crack at the plate of the unidirectional CFRP due to ply angle. The thickness of plate is 2 mm. Two laminates with the varied ply angles are layered and eight plies are made. The hole is placed at the center of plate and the cracks with the length of 2 mm are generated on both left and right sides from the hole. The finite element program of ANSYS is carried out in order to analyze the CFRP with fiber layer. As analysis, the maximum reaction force and equivalent stress are investigated due the angle of ply. The reaction force in case of the stacking angle of 90° is shown to be greatest among all specimens.

An aluminum with the light weight has been used at the automotive car body. As the aluminum is applied to the automotive seat, the optimum design becomes important by investigating the mechanical properties. This study aims at suggesting the basic data for the optimum design of automotive seat frame. In this study, the mechanical properties are investigated through the simulation analysis on the entire structure of seat frame. Two study models using the real commercial vehicles are designed with CATIA program and analyzed with ANSYS program. The harsh condition during the driving state is supposed by using the analyses of natural frequencies and harmonic responses. As the real frequency ranges in this study are set by selecting the natural frequencies through modal analysis. The critical frequencies are analyzed by harmonic response on which the driver is seated. The values of maximum equivalent stresses at models 1 and 2 are shown to be 18.073MPa and 2259.2MPa respectively. The critical frequency at models 1 and 2 are also shown to be 77 Hz and 206 Hz. The maximum stress at model 1 becomes far bigger than model 2. By comparing two models, model 1 has more critical condition than model 2. At the design of automotive seat frame at the dynamic vibration condition, the material of design with the durability and safety can be secured through this study result.

Separately from a single body, crash box is maufactured into the two alumnae by bonding adhesive. Crashbox has the property to absorb the shock by impact transferred to the car body at the collision between cars. In this study, the structural effect and performance are investigated according to the positions of holes punched at this crash box. The optimal structure is investigated for optimal design data of aluminum crash box. The equivalent stresses of study models distributed by compressive loads are compared with each other by using the analysis program of ANSYS. Total energies and mechanical strengths of study models at the real situation are also analyzed. As analysis results, the maximum equivalent stresses of 40880MPa, 42368MPa, 43176MPa, 44960MPa and 43476MPa are shown at study models due to the hole positions of 10mm, 15mm, 20mm, 25mm and 30mm from the upper plane of crash box respectively. Also, the total energy on analysis are verified within the error range of 10 % by comparing that on experiment at the hole position of 10mm. It is thought that the crash box due to the hole position from the upper plane of crash box can be effectively designed through this study result.

As CFRP with only a single material shows the various fracture properties, it has been applied to the many areas through the whole industry. The method bonding with adhesive has been recommended to apply the CFRP to structure. But it is inevitable that the mechanical joints with bolt, nut and rivet have been used sometimes. This study investigates the effect that these joints influence the CFRP panel through the analysis result. The analysis models as CFRP panels with the thickness of 5 mm have four kinds of layer angles which are 30°, 45°, 60° and 75°. The fracture property is examined when the pressure by the mechanical joint is applied to the upper panel. As the joint pressure is distributed most effectively in case of the layer angle of 60°, it is shown that this pressure becomes lower and the deformation of panel becomes lowest. On the basis of this study result, it is thought that the foundation data for the design of CFRP structure can be provided and contributed to the safety design of structure.

In this study, the analyses of structure, fatigue and vibration with two models of 1 and 2. As the result of structural analysis, the equivalent stress and the total deforamtion of model 1 become higher than those of model 2.Model 1 shows fatigue life more than model 2. As the vibration analysis, model 1 has the safety better than model 2. As shown by these results, the main parts ofdamage and the weak areas can be investigated to differ from each other according to the configuration of model though these models have the same material property. The result of this study through the analysis can be applied to develop the optimal design of automotive seat frame with durabilty and safety.

가루깍지벌레(Pseudococcus comstocki)는 노린재목 가루깍지벌레과로 포도원에서 나무껍질 사이에 알, 약충 및 성충으로 월동하고, 봄철 포도나무 수액이 이동할 즈음 활동을 시작한다. 개체수가 증가하는 7월 중순에 이동을 시작해 결과지와 봉지를 씌운 포도과실에서 흡즙하고 감로를 배설하여 그을음병을 유발한다, 7월 하순 ~ 8월 상순 경에 포도 과실 지경에 알을 낳으며, 포도 수확기인 9월 상순 무렵 약충이 증가함에 따라 그을음이 늘어 포도 상품성을 떨어뜨린다. 더욱이 유기포도원 의 알렉산드리아 같은 청포도계통의 포도에서 피해 증상이 뚜렷이 나타나 농가피해가 심하다. 본 연구는 가루깍지벌레의 피해를 줄이고자 식물로부터 유래하는 기피물질을 탐색하고자 수행하였다. 27종의 essential oils을 4 Choice Insect Olfactometer(4 CIO)의 2구를 이용해 후각검정을 실시한 결과 반응을 보인 8 essential oils을 1차 선발하였고, 8 essential oils을 4 CIO의 4구에 각각 5㎕, 10㎕, 15㎕, 무처리로 처리한 결과 Orange oil에서 73%의 기피효과를 보였으며, Castor oil, Gerarium oil, Thyme oil에서도 기피효과를 보였다.

국내 시설포도 재배면적은 2006년 1,824ha에서 2012년 2,591ha로 42.1% 증가되었다(통계청). 이후에도 수입과실에 대한 경쟁력 강화를 위해 지속적으로 늘어 응애류, 총채벌레류, 애매미충류, 깍지벌레류 등의 미소해충 발생이 증가되고 있다. 이 중 잎응애인 점박이응애(Tetranychus urticae), 차응애(T. kanzawai), 사과응애(Panonychus ulmi)가 포도원에서 발견되었고, 점박이응애가 우점종으로 알려져 있다. 시설재배시 고온으로 인해 해충 번식속도가 빠르고 연중 번식이 가능하여 많은 회수의 약제 살포가 필요하며, 이로 인해 농가의 방제비용 및 노동력이 많이 들어 어려움을 호소하고 있다. 본 연구는 초미립 자동연무기(삼영바이오, NSY-350)를 이용하여 시설포도원에서 점박이응애의 방제효율을 검정하고자 수행하였다. 10a 기준 관행 동력분무기에 비해 80.3%의 약제량과 3.6%의 물량으로 사이에노피라펜 액상수화제를 살포했을 때 점박이응애를 100% 방제하였다. 살포준비를 위한 시간도 관행에 비해 10%밖에 안 들었으며, 포도잎이 겹친 사이에 농약 흡착지를 놓고 농약부착능력을 검정한 결과, 관행 일반분무기에 비해 부착효과가 인정되었다.