• 한국가구학회지
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• 제12권1호
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• pp.125-130
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• 2001

The sofa industry, which is now one of the major furniture industries in Korea, has developed since 1970s as the apartment building boom and the rise of living standards triggered its demand. Among others, durable and high-quality leather sofa had been most favored and excelled other sofas since mid-1980s along with the growth of national economy before IMF control tightened money market in late 1990s. Leather sofa is still favored and its industry has great possibilities to increase as people tend to seek higher and more personalized living conditions with the stabilization of economy. However, there are several problems in the sofa industry due to the current economic difficult conditions, i.e.; 1. It is hard to cut down the cost of raw material as the supply mostly depend on import. 2. It is hard to keep product quality due to technical difficulties. 3. There are still illegal duplicates of foreign or domestic competitors'design. The aim of this study is to examine the reality of the leather sofa industry in Korea and to suggest new vision for its progress.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.866-869
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• 2000

To improve quality of the ground surface, we have to consider a number of parameters. But it is difficult to make experiment with many parameters. Most of all experiments try to search optimal grinding condition with conservative factors such as feed rate, depth of cut, wheel rotating speed, etc. But This paper attempts to view the significance of some different factors effecting on the surface roughness by introducing helical scan grinding method and material removal rate. The design of experiment is used to find the optimal grinding condition which minimizes the surface roughness value bout optical glass material. To analyze experimental results, ANOVA(ANalysis of VAriation) is used. Discussion on the result about helical scan grinding is also given.

• 한국산업융합학회 논문집
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• 제26권6_3호
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• pp.1197-1204
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• 2023

Ti-alloy, a high-strength alloy material among the materials used in aircraft that are trending toward lighter weight, is classified as a difficult-to-cut material that requires a lot of energy for cutting. Cutting in a high-temperature environment is considered one means of making this possible, and various studies have been conducted on it. In particular, research on LAM (Laser Assisted Machining (LAM)), which utilizes laser heating of the cutting area, is being actively conducted. Before processing of the milling cutter begins, the temperature is raised locally by the laser irradiated through the laser head carrier, and the resistance during milling is reduced. Therefore, in this paper, in order to derive such conditions, we performed heat transfer analysis according to transfer conditions and compared it with actually applied test data to use it to establish appropriate processing conditions.

• Design & Manufacturing
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• 제10권3호
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• pp.34-38
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• 2016

Roll forming is a continuous production process that is mass-produced. The roll forming process is produced in various forms. The special feature of roll forming is a continuous production. Therefore, the process of cutting the material is essential. The troubles in a shearing process affects the low productivity. Accordingly, it is important to reduce the factors that inhibit the material flow. And it is difficult to apply the common shear angle. Because it is not a simple forms, such as a progressive die. This study shows how to select the angle of a shear punch and the shape of a cutting punch in the product with a specific shape. Conclusively through three different model, it is advantageous to apply the different shear angle and clearance along the forms.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.73-78
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• 1994

Wear and fracture mode of ceramic tool for hardened SKD11 steel was investigated by face milling in this study. The cutting force and Acoustic Emission(AE) signal were utilized to detect the wear and fracture of ceramic tool. The following conclusions were obtained : (1) The wear and fracture modes of ceramic tool are characterized by three types: \circled1wear which has normal wear and notch wear, \circled2 wear caused by scooping on the rake face, \circled3 large fracture caused by thermal crack in the rake face. (2) The wear behaviour of ceramic tool can be detected by the increase of mean cutting force and the variation of the AE RMS voltage. (3) The catastrophic fracture of ceramic tool can be detected by the cutting force(Fz-component). (4) As the hardness of work material increased, Acoustic Emission RMS value and mean cutting force(Fz) increased linearly, but the tool life decreased.

• 한국환경복원기술학회지
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• 제13권3호
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• pp.128-142
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• 2010

This study examined the actual conditions of quarries. aiming to offer preliminary data to help with restoration efforts of quarries after extracting rock material. The results are as follows. As for the current state of business, a classification of all sites surveyed showed the ratio of ceased operations: ongoing operations: quarries under restoration to be 58:5:37. Classified by the permit area, the ratio of the number of quarries with areas less than $20,000m^2$ (2ha) : between $20,000m^2$ (2ha) and $50,000m^2$ (5ha) : $50,000m^2$ (5ha) or more was 15:60:25. The classification by use of the rocks showed the ratio of construction aggregate (such as civil construction material) : building material : craft material to be 60:28:12. The ratio of quarrying methods of bench cut : slope quarry : vertical quarry wall is 40:18:42. It is indicated that 85% of all quarries surveyed are difficult to reclaim while 15% seem to be easier to restore. Among all surveyed, 34 sites were considered to be extremely difficult to restore. 17 of the 34 sites (50%) were quarry walls almost vertical that have been neglected after extraction. 16 of them (47%) were underground quarries that have left quarry walls deep under the ground. For the remaining 1 site, there doesn't seem to be any need for reclamation as it became totally flat after the extraction.

• 한국전산구조공학회논문집
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• 제36권3호
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• pp.165-171
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• 2023

건설기계와 특장차의 상부와 하부 구조를 연결하는 로터리 조인트는 축과 하우징이 회전하면서 유압을 전달하는데 오일의 유로에 누유를 방지하기 위해 여러 개의 시일이 조립된다. 시일재료는 강성이 커서 조립에 어려움이 있기 때문에 자른 후 조립하는 방법을 모색하였다. 절단면의 모양은 L형과 /형으로 하였고 유압이 작용할 때 누유 기준은 절단면에 발생하는 접촉압력으로 하였다. 시일의 구조와 재료는 이중 탄성중합체로 구성되며 강성이 큰 PE 재질만 절단한 경우에 대하여 비선형 접촉 구조해석을 수행하였다. 연구결과 절단 길이가 짧을수록 누유 방지에 유리하며 PE와 하우징이 접촉하는 윗면보다 NBR과 PE가 접촉하는 아랫면으로 누유될 가능성이 큰 것으로 나타났다.

• 한국기계가공학회지
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• 제4권3호
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• pp.32-38
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• 2005

Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though very hard materials and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM process is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods. In this experimental thesis, the super EDM drilling was developed for high precision semiconductor die steel and for minimization of leadframe width. It was possible to development of EDM drilling machine for high precision semiconductor die with the electrode guide and its modelling and stress analysis. The development of electrode with the copper pipe type was conducted to drill the hole from the diameter of 0.1mm to 3.0mm with the error of from 0.02mm to 0.12mm. From the SEM and EDX analysis, the entrance of the EDM drill was found the resolidification of not only the component of tungsten but also the component of copper.

• 대한두개안면성형외과학회지
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• 제16권1호
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• pp.29-30
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• 2015

In cleft palate surgery, the environment is especially critical when suturing. Encum-bered, obstructive space in the environment can hinder a suture while using the Dingman mouth gag. We introduced a novel but simple draping technique. A simple hand towel is placed over the gag. A hole is cut out in the middle according to each patient's mouth. After making the hole, the hand towel is soaked in water and gently squeezed. Then the towel is properly placed over the Dingman mouth gag. Dripping water on the hand towel during the suture helps keep it in place. Using this draping technique, we cut 14 minutes of operation time compared to the average operation time of the past 2 years. There were several disadvantages in previous draping method. First, long suture material may easily get caught. Second, the operation field can easily be contaminated. Third, focusing on the operation becomes difficult due to the obstruction. This draping technique can compensate for the disadvantages of the previous Dingman mouth gag.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.89-94
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• 2003

Hard coatings are known to improve the performance of cutting tools in aggressive machining applications, such as high speed machining. New superhard Ti-Al-Si-W films, characterized by a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous $Si_3 N_4$ matrix, could be successfully synthesized on WC-Co substrates by a hybrid coating system of arc ion plating(AIP) and sputtering method. The hardness of Ti-Al-Si-N film increased with incorporation of Si, and had the maximum value ~50 GPa at the Si content of 9 at.%, respectively. And the X-ray diffraction patterns of Ti-Al-Si-N films with various Si content is investigated. In this study, Ti-Al-Si-N coatings were applied to end-mill tools made of WC-Co material by a hybrid coating system. Cutting tests fir the high-hardened material (STD11,$H_R$)C62 and their performances in high speed cutting conditions were studied. Also, the tool wear and tool lift of Ti-Al-Si-N with various si(6, 9, 19) contents were measured.