• 대한치과보철학회:학술대회논문집
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• 2000.11a
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• pp.80-80
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• 2000

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.438-441
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• 2004

In this paper, an apparatus for unbinding the rope is studied to solve continuous work of the auto cleaning apparatus of a pillar. During operation of the auto cleaning apparatus of a pillar, in order to not swing the apparatus is down by it's weight according as electric motor velocity. We focus on the design and the implementation to upgrade the auto cleaning apparatus of a pillar that had been implemented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.243-250
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• 2014

Fiber-optic cables towed by underwater vehicles have an important role in enhancing the mission capability of a mother ship. In general, fiber optic cables are unwound in water for securing unwinding stability and preventing unwinding-related problems. Therefore, in this study, the numerically simulated result is verified against the experimental result in water, and the cable-unwinding motion is predicted based on the increase in unwinding velocity. The experimental apparatus is composed of a water tank and a winder, and a high-speed camera is used for photographing the cable-unwinding motion. The numerical result defined in the Cartesian coordinate system is solved using a transient-state unwinding equation of motion. The numerical result agrees well with the experimental result, and it can predict cable-unwinding behaviors in according to an increase in the unwinding velocity.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.523-526
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• 2010

In this study, we demonstrated a development of a non-releasing bolt which is fastened with a target by expanding a certain area of a bolt body. Being released a bolt causes many problems in a field where bolts are used. In order to figure out the problems, currently, many types of a non-releasing bolt have been developed and have been using. Unfortunately, however, they do not perfectly function not to be released. Therefore, the structures builded with bolts have many problems caused by external stress such as vibration and shock, and thus the bolts have to be regularly tightened for maintenance. With the important factors of internal geometry, the amount of explosive, and the firing pin, we developed a technology which could control the expansion degree of a certain area on a bolt body. Based on the results, it was founded that the performance of non-releasing was linearly proportional to the degree of body expansion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.1004-1011
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• 2018

Recently, pyrotechnic separation nut has attracted a considerable attention because of its shock reduction effect among various pyrotechnic mechanical devices. However, its bolt loosening behavior under transverse vibration has not been studied sufficiently, since segmented nuts are utilized instead of conventional nut in pyrotechnic separation nut. With the background, bolt loosening analyses are carried out referring to Junker vibration test. The analysis procedure consists of two steps. The first step is the bolt fastening step, screwing the bolt by fastening torque. The second step is the bolt loosening step under transverse vibration. Through the procedure, bolt loosening behaviors are obtained, and the effect of clearance on loosening behavior is closely investigated for reliable design of pyrotechnic separation nut.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.157-168
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• 2008

Tightening of the screws in implant restorations should be accurate and precise. If applied torque is too low, screw loosening would be occurred. With too high torque, the screw fracture might take place. Various torque generating devices are developed and employed to apply a proper torque. The purpose of this investigation was to determine and compare the accuracy of the torque controllers. In this study, 4 types of torque controllers were used; electronic torque controller, torque limiting device, torque indicating device and contra angle torque driver. Digital torque gauge was employed to measure the de-torque value. Thirty cycles of tightening and loosening were done with each torque controller. All implant torque controllers have shown slight errors and deviations. The torque liming device exhibited the most accurate data. No significant difference was found among the mean de-torque values of the electronic torque controller, torque indicating device and contra angle torque driver. In the limitation of this study, it would be recommended that the implant torque controllers should be checked whether uniformed and precise torque can be generated and a measuring error should be corrected.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.419-432
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• 2010

Various torque generating devices have been developed and employed to apply a proper torque. These devices are usually calibrated by the manufacturer to apply appropriate torque levels for their specific implants and attachments. The purpose of this investigation was to determine and compare the accuracy of the torque controllers. In this study, 4 types of torque controllers were used; torque limiting device(TLD), torque indicating device(TID) and contra angle torque driver(CA), electronic torque controller(ETC). Digital torque gauge was employed to measure the de-torque value. Thirty cycles of tightening and loosening were repeated with each torque controller. All implant torque controllers have shown slight errors and deviations. The contra angle torque driver exhibited the most accurate data. In the limitation of this study, it would be recommended that the implant torque controllers should be checked whether uniformed and precise torque can be generated and a measuring error should be corrected.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.65-72
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• 2010

The failure of expansion joints for bridges generally occurs in non-shrinkage mortar another problem is the release of anchors in expansion joints due to the impact and vibration that occurs when cars are driving over a bridge. In this study, to overcome the failure of expansion joints that is related to the failure of non-shrinkage mortar, an elastomeric mortar has been developed. The elastomeric mortar has a highly developed pull-out capacity compared with that of non-shrinkage mortar. Moreover, an anchor system that can be changed easily and prevent the fracture of expansion joints has been developed.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.100-100
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• 2017

2016년부터 중국에 수출한 진공포장 쌀이 진공이 풀려 중국 현지 소비자들에게 품질에 대한 신뢰저하로 외면 받아 판매에 어려움을 겪었다. 진공풀림 원인은 주로 포장재의 모양, 과열 열접착 및 운송 중 부주의 등을 들 수가 있다. 따라서 본 연구에서는 쌀 진공포장 후 진공 풀림현상이 발생되는 원인을 분석하고, 진공포장에 적절한 포장재 및 취급조건에 대해 구명하여, 중국 쌀 수출 시 품질신뢰도 및 경쟁력 제고로 쌀 수출 확대를 위해 진공 포장재, 진공포장기술 및 운송 취급 방법을 제시하고자 하였다. 미곡종합처리장에서 사용하고 있는 플라스틱 필름 포장재의 적합 여부를 살펴보기 위하여 산소투과도 및 투습도를 산소투과도 측정장치(OX-Tran Model 2/61, Mocon, USA), 투습도 측정장치(Permatran-W Model 3/33, Mocon, USA)를 이용하여 측정하였다. 적정 열접착 온도를 구명하기 위하여 열접착 작업시간 간격 3, 5, 10초 3수준으로 하고 가열시간을 0.2초~2초까지 9수준으로 설정하여 포장필름을 열접착한 후 접착상태를 조사하였다. 진공 포장된 쌀을 골판지상자에 2차 포장하여 운송할 때 진공풀림 현상이 발생 여부를 조사하기 위해 가상 운송시험을 진동시험 장치를 이용하여 수직 및 수평으로 진동시험을 수행하였으며, 또한 취급조건에 따라 진공풀림을 조사하기 위하여 골판지 상자단위, 비닐포장 단위로 50, 70, 90cm 높이에서 낙하 시험을 하고 진공풀림여부를 조사하였다. 유통 중인 쌀 진공 포장재는 나이론(nylon)+선형저밀도폴리에틸렌(LLDPE) 복합필름으로 산소투과도가 $30{\sim}70cc/m^2{\cdot}day$, 투습도가 $2{\sim}4.5g/m^2{\cdot}day$로 산소투과도 및 투습도가 충분히 낮아 진공포장재로 적합했으며, 적정 열접착온도 조건은 $130{\sim}150^{\circ}C$에서 1~1.5초가량 가열해야 되는 것으로 조사되었다. 진동시험 및 낙하시험결과, 골판지박스 포장 시 완충재를 사이에 넣은 경우 진골풀림이 적었고, 상자단위나 비닐포장단위 모두 가능한 50cm보다 높은 곳에서 낙하충격을 받지 않도록 취급해야 할 것으로 판단되었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.793-796
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• 2008

The failure of expansion joint for bridge is generally occurred on the non-shrinkage mortar and other problem is the release of anchors in expansion joint due to the impact and vibration during the driven car on the bridge. In this study, to overcome the failure of expansion joint by the failure of non-shrinkage, the elastomeric mortar is developed. The pull-out capacity developed elastomeric mortar compared with that of non-shrinkage mortar. Moreover the anchor system which can be change easily and prevent a fracture of expansion joint is developed.