• 한국기계가공학회지
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• 제18권6호
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• pp.98-105
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• 2019

In order to improve the fuel economy and dynamic behavior of automobiles, the weight reduction tendency of automobile parts is obvious. Also, in order to maximize assembly and maintenance convenience, various parts are integrated and modularized. Multi-piece methods require many manufacturing processes and become a factor of lowering the strength of parts. It is advantageous to overcome the disadvantages by integrally manufacturing to reduce the processing steps and ensure the strength of the parts. However, when it is necessary to process in a narrow space inside the part, it is impossible to process with the existing spindle. The angle head spindle is only a component of a machine tool, but it is a core part that requires high technology and is highly utilizable in products requiring high precision machining. Therefore, various and continuous studies needs for angle head spindles in areas such as vibration absorption, operational safety, excellent dimensional stability, and strength. In this paper, we propose an optimal design for angle head spindle by performing structural analysis and shape optimization for angle head spindle gear and case.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1645-1651
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• 2015

본 연구에서는 선삭 작업에서 가공 여유각 변경에 따른 피삭재의 형상정밀도가 어떻게 변화되는지 분석하고자 하였다. 피삭재는 3가지로 SM45C(기계구조용탄소강), SCM415(크롬몰리브덴강), STS303(스테인리스강)을 선택하여 정해진 가공조건인 회전속도 2,500 rpm으로 시작하여 이송속도 0.07 mm/rev와 0.10 mm/rev를 기준으로 가공깊이 0.1 mm, 0.2 mm, 0.3 mm 그리고, 절인 경사각인 네거티브 경사각 $0.0^{\circ}(-6.0^{\circ})$, $0.3^{\circ}(-6.3^{\circ})$, $0.9^{\circ}(-6.9^{\circ})$의 3가지 형태로 가공하였을 경우, 재료별 가공정밀도, 원통도, 동축도, 진원도 등의 결과를 비교 분석하였다. 피삭재의 재질별로 알아본 원통도의 정밀도는 $0.0^{\circ}{\rightarrow}0.3^{\circ}{\rightarrow}0.9^{\circ}$의 순으로 $0.9^{\circ}$일 경우가 가장 좋은 원통도 값을 나타냈다. 결과적으로 바이트의 네거티브 경사각이 커지면 정밀도가 특정 부분에서 재질에 관계없이 좋아져서 가공성이 향상됨을 알 수 있었다. 또한, 이송속도와 절삭 깊이에 따라 가공형상이 변화한다는 것과 재질에 따라 다르게 적용되어야 한다는 것을 확인하게 되었다.

• 한국건축시공학회지
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• 제1권2호
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• pp.185-190
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• 2001

The purpose of this study is the development of practical Dry floor tile unit method that settle the defect of a wet method and designed for resin mat. With use of PE resin which is confirmed the basic property, it is developed that resin mat, joint-sealing compound with fixed form and space management to Dry floor tile unit method. The result of this study is below. 1) To acquire above the 4kgf/$\textrm{cm}^2$ - construction specification criterion, the bonding space that between resin mat and tile has to occupy the 50% of resin mat module space(10,000$\textrm{cm}^2$). 2) Criteria of bonding part plane is below. simpleness of metal form. productivity, uniform quality after injection molding cooling, easy cutting for remain space management, adhesive property, construction ability, transformation of a severed piece under pressure and so on. 3) To get the shape that could protect the interfacial breakdown, it is designed that resin mat and tile are unified after the bond input. 4) Adapted joint-sealing compound is the material of urethane kinds wedge form. Resin mat has the water passageway that could drain the water. 5) To manage the severed piece of tile, the resin mat is likely to divide the half and the quarter and the plastic drainage is developed in the severed piece.

• 대한기계학회논문집A
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• 제26권6호
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• pp.1120-1126
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• 2002

Machining characteristics of tool steels manufactured by electro slag casting process has been investigated in this study. For the estimation of machinability, turning and drilling tests are carried out. The chip shapes at various velocities are investigated for the comparison of turning workabilities of tool steels because the chip shapes reflect characteristics of cutting resistance. In case of drilling test, feed motor currents measured by a hall sensor are used as a measure for the drilling resistance. The machining characteristics of the tool steels are strongly correlated with tensile properties, such as tensile strength, hardness, and ductility. In case of turning workability, it was found to be favoured by the higher tensile strength, while the opposite is true far the drilling workability. The electro-slag casted materials show better turning workability in the viewpoint of chip shapes and, the quenching-tempered electro-slag casted material has relatively better drilling machinability than that of the annealed one.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1285-1288
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• 2005

Screw rotors, the key parts of screw compressors, are used in compressing air and refrigerant due to their high productivity, compact size, low noise and maintenance. In general, a screw compressor is composed of a pair of rotors of complex geometric shape. The manufacturing cost of the screw rotors is high because the complicated helical shapes of the screw rotors are manufactured usually by the dedicated machine tools. In this study, rotor profile is divided into three parts for the efficient machining. The formed tools are designed and shared for the respective split region. By cutting the screw rotor using the formed tools, this method is more efficient than the end mill in machining rotor. Experimental results show that 4-axis machining using formed tools needs less time and has the accuracy.

• 한국잠사곤충학회지
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• 제32권2호
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• pp.101-104
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• 1990

가을철 가지뽕 수확 후 가지의 절단부위 가운데 건증상을 띤 병$에서 Erwinia carotovora subsp. carotovora가 분리 동정되었다. 1)본 세균은 간장으로 4-8개의 주성모를 가진 0.4-0.8$\times$1.66-2.25$\mu\textrm{m}$ 크기의 임의혐기성 세균으로 감자,당근 절편을 $폐시키고 뽕나무에 강한 병워성을 갖고 있다. 2)King's B배지에서 난백색 균총을 형성하고 Gram 및 Inositol test 결과 음성반응, Pectin을 분해, Gelatin을 액화시켰다. 3)본 세균은 분류학적 특성이 Erwinia carotovora suasp. carotovora와 일치하였으며 일본에서 1978년에 보고된 바 있으나 국내 미기록 세균이다.

• 한국조경학회지
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• 제24권1호
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• pp.1-14
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• 1996

The purpose of this study was an analysis of the elementary school child's attitude and dangerous factors of play apparatuses n elementary schools. The results were summarized as follows; 1. 53.0% of the reply child thought that play apparatuses were dangerous, and 41.0% of the total reply had experienced accidents by apparatuses, the child under 10 had experienced the accidents manytimes. 2. The types of injuries most frequently occurred are falls from play apparatuses, and part of the body most frequently injured parts of the body are arms and legs. 3. The danger of fall in play apparatuses that is over 3M amounted 19.6%, it asked safety of bottom materials. 4. Destructed play apparatuses reached up to 20.0%, and rusted or decomposed apparatuses reached to 28.4%. 5. The distance of each apparatus were very close ; it was within 0.3~1.5M, which was 24.9%, it was very dangerous factor. 6. The most frequent hazards of educational play apparatuses are ; - inappropriate size of apparatuses(height, gap, thick etc.)- inappropriate shape and finished state(bad welding and cutting, projection part etc.)- unsuitable use of bottom material in playground and safety color.- insufficient use zone.-inappropriate maintenance and inspection(endurance passage, erosin of iron-ware and wooden ware, projection of foundation concrete)

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.290-293
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• 2001

The mid-schedule planning of the ship is making a schedule about the process from cutting to erection. The ship consists of lots of blocks. This block has different process because of the shape of the block varies in accordance with the ship-type and the part position of the ship. The type and order of each block process initially must be generated for the mid-schedule planning. In this paper, the process planning, described as above is preparing the basic information before scheduler make a plan with the prepared manhour. The scheduling is done with this process planning which includes the information of the process order. This paper shows the research about three methods to design the process planning. First, investigate the expression method about information of the process planning for the mid-schedule planning in real workplace. Second, design the object of the process planning on the basis of investigating the expression method. Finally, develop the prototype of object on the basis of this designed process planning and then find the practical use in the mid-schedule planning. The object, which is developed in this paper, contains the main algorithm. In case of developing The Mid-Schedule Planning System, this object is expected to be utilized very easily as consisting another object.

• 수산해양기술연구
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• 제22권4호
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• pp.32-40
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• 1986

A model experiment of purse seine by the circulating water tank was carried out on the changes of net shape and the tension of purseline under operation in two layer current. In the circular tank, the two layer current was made by cutting off the current of upper layer and producing the bottom current by the equipment shown in Fig. 1. The model experiment of purse sein was made on a reduced scale 1 :400, and the experiment was carried out according to the Tauti's model law. When the bottom current of O. 5 knot flows to lower part of three-eighths of net, following results are derived. The depth of sinkerline reached only about 80% of that of no current set. The horizontal shift of sinker line caused by the bottom current is maximized in tight set. The enclosed area by the floatIine immediately after the completion of set net is 61. 5% in tight set, 50. 0 % in loose set and 54. 1 % in lateral set of those in the case of no current. In the first half period of pursing, the tension of the purseline is enhenced by the bottom current and the pattern of increasing is irregular in the tension curves.

• 대한조선학회논문집
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• 제36권3호
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• pp.122-133
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• 1999

완성되어진 블록을 이용한 탑재의 과정에서 발생하는 블록 경계간의 판재 겹쳐짐 현상, 과도한 간격 및 단차의 발생현상은 선박의 건조비용과 공수를 증가시키는 요인이 된다. 본 논문에서는 블록의 조립 및 탑재에 관한 시뮬레이션 시스템을 제안하고 이중 조립에 관한 시뮬레이션을 용접순서에 따라 용접변형 및 자중을 고려하여 유한요소해석을 ANSYS를 이용하여 수행하였다. 용접에 의한 변형은 실험에 의한 변형량을 이용한 등가강성에 따른 등가 하중을 사용하여 탄성적인 해석법을 수행하여 예측하였으며 선체 이중저 평블록을 패널 조립법에 근거한 조립순서에 따라 시뮬레이션을 수행하였다. 시뮬레이션을 통한 변형으로부터 조립순서에 따른 중간 제품의 형상의 변화에 의한 강성의 변화에 기인한 변형량의 차이를 확인 할 수 있었으며, 자중의 효과를 반드시 고려하여야 함을 확인 할 수 있었다.