• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3692-3697
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• 2015

A screw is a type of fastener characterized by a helical ridge known as thread. The demands for screws with the miniaturization and weight reduction are increasing for the trend of small size of mobile devices. The successful designs of mold and process are very important to obtain screws with good mechanical properties and high precision. In this study, the design of cold forging process of micro screw was carried out by using finite element method. In particular, in order to investigate the effects of die geometries and friction, design of experiment method was adopted and it was revealed that the friction was the dominant factor of folding defects. From these results, the design of die was modified and experiments were carried out with the modified die. From the experimental results, it was found that the folding defects disappeared.

• Fire Science and Engineering
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• v.26 no.4
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• pp.82-88
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• 2012

To analyze the thermal characteristics of wire connection part that is connected to a screw-clamping terminal block depending on screw torque, the normal screw torque defined in KS C 2625 and the abnormal screw torque that can occur due to loosened screws resulting from defective work or aged deterioration were used as experimental variables. After the same load was applied to normal and abnormal screw torques, the thermal characteristics of the wire connector were measured and compared with a thermal imaging camera. The findings from this study will be used to detect heating due to defective screw torque at terminal block connections during electric safety inspection in the future and minimize the hazard of electric fire.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.12
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• pp.1675-1683
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• 2018

This paper is a study on modeling of an NFC antenna to be inserted into a steel pallet for conveying selected good products through a vision system to a threaded screw from CNC equipment. The CNC equipment used here incorporates the information communication technology (ICT) corresponding to the Internet of Things (IoT), and the smart factory system technology that produces information by exchanging information freely in two directions by connecting the POP corresponding to the service Internet is evolved Equipment. Therefore, it is possible to collect position information on the threaded workpiece by applying NFC antenna designed considering iron pallet used for material management so as to grasp estimated completion time and actual production amount according to production instruction from existing analog type equipment to POP monitoring system And investigated its characteristics.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.3
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• pp.179-187
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• 2018

Purpose: The purpose of this study was to investigate the effect of heat applied to disintegrate cement on the removal torque value and fracture strength of titanium abutment and abutment screw. Materials and methods: Implants, titanium abutments and abutment screws were prepared for each 20 piece. Implant abutments and screws were classified as the control group in which no heat was applied and the experimental group was heated in a vacuum furnace to $450^{\circ}C$ for 8 minutes and cooled in air. The abutments and screws were connected to the implants with 30 Ncm tightening torque at interval 10 minutes and the removal torque value was measured 15 minutes later. And the fracture strength of abutment screw was measured using universal testing machine. Results: The mean removal torque value was $27.84{\pm}1.07Ncm$ in the control group and $26.55{\pm}1.56Ncm$ in the experimental group and showed statistically significant difference (P < .05). The mean fracture strength was $731.47{\pm}39.46N$ in the control group and $768.58{\pm}46.73N$ in the experimental group and showed statistically no significant difference (P > .05). Conclusion: The heat applied for cement disintegration significantly reduced the removal torque value of the abutment screw and did not significantly affect fracture strength of the abutment screw. Therefore, in the case of applying heat to disintegrate cement it is necessary to separate the abutment screw or pay attention to the reuse of the heated screw. However further studies are needed to evaluate the clinical reuse of the heated screw.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.318-322
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• 2005

In this study the regression rate of hybrid rocket fuel has been investigated by swirl injectors and helical grains. Tests have been done with two kinds of injector and helical grain. In this paper the swirl injector and helical grain were varied to find the optimal condition to obtain the max regression rate for a given operational condition.

• The Journal of the Acoustical Society of Korea
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• v.9 no.3
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• pp.31-41
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• 1990

It is difficult to detect such flaws as stress-corrosion cracking or corrossion wastage(loss of bolt diameter) in the threads. In many cases the critical size of a flaw is very small(1-2mm order). This paper describes how it is possible to discriminate small flaw indications in threads using the time difference of thread signals [TDTS] by a signal-conditioning technique.

• 월간 기계설비
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• s.288
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• pp.75-80
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• 2014

나사식 가단주철제 관이음쇠는 신한메탈, 영화테크(전신 영화금속) 외 국산 8개사, 중국산 9개사 등 모두 17개사가 공급에 참여하고 있다. 그러나 심한 가격경쟁으로 짝퉁과 중국산 제품이 판치는 시장에서 100% 국내 가공으로 최고의 품질을 자랑하며 고객과 신뢰를 쌓아가기란 여간 어렵지 않다. 나사식 가단주철제 관이음쇠 분야의 명품을 꼽으라면 설비건설업계는 대부분 다이아몬드가 표시된 제품을 집는다. 다이아몬드 표시로 더 알려진 관이음쇠 생산업체인 (주)신한메탈(대표 전진화)은 작년에 영화금속의 나사식 관이음쇠 부문을 인수한 후 경쟁력을 더욱 강화한데 이어 최근에는 엘보, 티 등 스테인리스 조인트 가공시장에 본격 진출하기 위해 생산시설 도입에 박차를 가하고 있다.

• The Journal of the Acoustical Society of Korea
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• v.12 no.3
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• pp.5-12
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• 1993

볼트와 너트에 대한 초음파비파괴검사는 종파와 사각 횡파 기술을 사용하고 있는데 작은 결함신호는 자사산의 신호와 크기가 비슷해 구분이 되지 않는다. 본 논문에서는 나사산의 다중반사신호로부터 결함신호를 구분할 수 있는 방법을 제시한다. 종파를 사용하였을 경우 균열의 선단신호와 코너에서 반사되는 신호는 진행시간이 거의 같아 중첩되어 나타나지만 균열로 인한 Rayleigh파는 균열의 선단신호와 코너에서 반사되는 신호다음에 결함길이에 따른 미세한 진행시간을 가지고 나타난다. 이와는 다르게 횡파를 사용하였을때의 균열의 선단신호는 코너에서 반사되는 신호보다 앞에 나타난다. 이러한 나사산에 존재하는 결함의 선단신호를 기준으로 순방향 또는 역방향으로 반사되는 신호로부터 작은 결함신호도 구분할 수 있고 그 크기를 정량적으로 계산할 수 있다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.88-93
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• 2004

The main objective of the research is to Propose an algorithm that to estimate the screwing torque from parameters of DC motor current without using any stain gage and torque cell. The auto screw drive system is divided into two parts, one is the DC motor ind the other is mechanical part in which the friction torque and damping ratio are a function of rotational of spindle electro motive force constant. The torque is estimated from the friction torque. The research is concerned with applying the method to an auto screw drive and the advantages and limitations are also discussed in this paper.

• Journal of Veterinary Clinics
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• v.25 no.2
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• pp.131-135
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• 2008

A 5-year-old Chihuahua dog was evaluated for a tetraparesis. The dog was presented with a non-ambulatory tetraparesis and neck pain. Radiography demonstrated an atlantoaxial (AA) subluxation and increased distance between the dorsal arch of the C1 and the dorsal spinous process of the C2. The AA joint was fixed with ventral transarticular fixation using two screws under fluoroscopic guidance. Neck brace was applied during 3 weeks post-operation. After 4 weeks, the dog was fully ambulatory with improved neurological function. Postoperative radiographs confirmed reduction of the luxation and no migration of screws. The dog showed complete resolution of clinical signs without signs of recurrence till 4 months after operation. Proper angulations of screws provided under fluoroscopic guidance, enabled adequate stabilization of the AA joints using ventral transarticular screw fixation which improved neurologic outcome of the patient.