• 대한치과보철학회지
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• 제36권5호
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• pp.738-747
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• 1998

The purpose of this study was to compare the positional stability of removable dies using several dowel pin systems. The removable dies were made by using five dowel pin systems: single dowel pin(Group I), single dowel pin and prepared groove on the die base(Group II), two-single dowel pin(Group III), two separate parallel dowel pins with plastic sleeves(Group IV), double straight dowel pins with metal sleeve(Group V). Special aluminum mold was made for specimens, and the dies of specimens removed and replaced thirty times with universal testing machine. Horizontal and vertical shift of dies was measured by Olympus monocular scanning tunneling microscope(STM5). The results were as follows: 1. The vertical shift was larger than the horizontal shift in all the other groups except Group I. 2. Single dowel pin system(Group I) was the most unstable of five dowel pin systems. 3. Double dowel pin systems with steeve(group IV, V) were the most stable of five dowel pin systems. 4. This study indicates that excellent horizontal positional stability is attainable with use of additional groove on the die base or double dowel pin. and excellent vertical positional stability is attainable with use of sleeve.

• 디지털산업정보학회논문지
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• 제11권2호
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• pp.11-22
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• 2015

The almost of Web page has been gathered the personal information(Korean resident registration number, name, cell-phone number, home telephone number, E-mail address, home address, etc.) using the membership and log-in. The all most user of Web page are concerned for gathering of the personal information. I-pin is the alternative means of resident registration number and has been used during the last ten-year period in the internet. The accident of I-pin mass illegal issue was happened by hacker at February, 2015. In this paper, we analysis the problems of I-pin system about I-pin mass illegal issue accident and propose a improvement method of it. First, I-pin issue must be processed by the off-line of face certification in spite of user's inconvenience. Second, I-pin use must be made up through second certification of password or OTP. The third, the notification of I-pin use must be sent to the user by the text messaging service of cell-phone or the E-mail. The forth, I-pin must be used an alternative means of Korean resident registration number in Internet. The methods can reduce the problems of I-pin system.

• 융복합기술연구소 논문집
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• 제5권1호
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• pp.27-31
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• 2015

A Pin-fin array is widely used to enhance the heat transfer in the internal cooling passage. The heat transfer distribution around the pin-fin is varied by the horseshoe vortex and flow separation. The difference of heat transfer coefficient induces the large thermal stress, which is one of the major reasons to break of hot components. So, it is required to enhance the heat transfer on the back side of pin-fin to solve the thermal stress problem. This study suggests the pin-fin with inclined jet hole and complex pin-fin/dimple array to enhance the heat transfer on the back side of pin-fin. The heat transfer coefficient is predicted by the numerical analysis, which is performed by CFX 14.0. The numerical results are obtained at Reynolds number, 10,000. The results show that the heat transfer on the back side of pin-fin is increased in both cases. Beside, the wake, which comes from dimple and jet, helps to develop the horseshoe vortex and increase the heat transfer on the next row pin-fin.

• 한국IT서비스학회지
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• 제16권2호
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• pp.97-110
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• 2017

Due to development of IT, various Internet services via the non-face-to-face are increasing rapidly. In the past, the resident registration numbers (RRN) was used a mean of personal identification, but the use of RRN is prohibited by the relevant laws, and the personal identification services using alternative means are activated. According to the prohibition policy of RRN, i-PIN service appeared as an alternative means to identify a person. However, the user's knowledge-based i-PIN service continues to cause fraudulent issuance, account hijacking, and fraud attempts due to hacking accidents. Due to these problems, the usage rate of i-PIN service which performs a nationwide free personal identification service, is rapidly decreasing. Therefore, this paper proposes a technical safety enhancement method for security enhancement in the i-PIN-based personal identification service. In order to strengthen the security of i-PIN, this paper analyzes the encryption key exposure, key exchange and i-PIN authentication model problems of i-PIN and suggests countermeasures. Through the proposed paper, the i-PIN can be expected to be used more effectively as a substitution of RRN by suggesting measures to enhance the safety of personal identification information. Secured personal identification services will enable safer online non-face-to-face transactions. By securing the technical, institutional, and administrative safety of the i-PIN service, the usage rate will gradually increase.

• Tribology and Lubricants
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• 제23권3호
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• pp.95-102
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• 2007

In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. Moreover, the lead removal from the bush material has strongly reduced the capability of the anti friction material to accept asperity contacts. In this paper, before trying to find the pressure distributions on the oil film of piston pin bearings by the unsteady two dimensional thermohydrodynamic lubrication analysis in order to do the optimum design of the bearings of piston pin, it will be investigated the tendancy of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress.

• Tribology and Lubricants
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• 제24권3호
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• pp.133-139
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• 2008

In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated the effects on the film pressure distribution due to the change in maximum combustion pressure.

• Tribology and Lubricants
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• 제24권2호
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• pp.55-62
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• 2008

In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated how the changes in combustion pressure at exhaust and intake stroke and the pressure-viscosity index effect on the film pressure distribution.

• 디지털산업정보학회논문지
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• 제12권1호
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• pp.51-61
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• 2016

Because the Apple Pay which created by U.S's Apple Inc. and launch of Samsung pay in last August in domestic, people have high interest in Pin-Tech industries and new method of easy payment. In this paper, it will study newly introduced Pin-Tech industries and marketability of Pin-Tech industries. Also it will propose safe use of Pin-Tech services based on cases in domestic and overseas. This paper is organized as follows. In Chapter 2, it will study concept of Pin-Tech services and status of Pin-Tech services in domestic and overseas. In Chapter 3, it will look technical trends of Pin-Tech services. In Chapter 4, it will propose direction based on analysis of cases of Pin-Tech services. This paper will finish with conclusion in Chapter 5. Given the global trends, Korea is now just took the first steps in new Pin-Tech era. The Pin-Tech services are in situations that it is not yet activated in domestic due to the various financial regulations and procedures. In this paper, it will shows cases of concerns of Pin-Tech services and domestic authentication which relates to easy payment certification. If Pin-Tech services are develop with easy payment certification and adapt to domestic environment and develop based on stability and security as mentioned in this paper, domestic Pin-Tech services and security technology will grow to the world level. Also it requires unceasing research and efforts from relevant government officials, security companies and Pin-Tech ICT companies.

• 정보화정책
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• 제17권1호
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• pp.43-62
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• 2010

우리나라의 대표적인 개인 정보는 주민등록번호라고 할 수 있다. 정보화의 급속한 진전과 발전 그리고 인터넷이 우리 생활의 일부가 되기 시작하면서 가상공간에서 개인 정보 보호에 대한 문제가 제기되기 시작하였다. 특히 가상 공간에서의 주민등록번호 사용은 개인 정보 오남용 등의 프라이버시 침해와 관련한 여러 가지 사회 문제들을 야기하고 있다. 가상 공간에서 주민등록번호 사용으로 발생하는 이와 같은 문제들을 해결하기 위해 정부는 2000년대 초반부터 가상 공간에서 주민등록번호를 대체할 수 있는 수단을 꾸준히 모색해 왔고, 그 결과 2006년 10월 이후부터 5개 민간 기관이 참여한 '인터넷 주민등록번호 대체 수단(i-PIN)' 서비스를 시행하고 있다. 하지만 i-PIN 도입 이후에도 개인 정보 침해 사건의 감소는 이루어 지지 않았고, 오히려 대형의 개인 정보 유출 사건이 빈번히 발생했다. 이런 상황들은 i-PIN의 성공적인 정착의 필요성, 가상공간에서의 개인 정보 보호의 중요성을 일깨워 주고 있다. 따라서 이 논문은 i-PIN 정책이 성공적으로 정착할 수 없었던 이유를 분석하고자 했다. 현재 정부의 주민등록번호 대체 수단인 i-PIN을 정책집행에 관한 이론 모형으로 분석하여 안전한 주민등록 번호 대체 수단의 효율적인 구현 방안을 모색하고자 한다.

• Restorative Dentistry and Endodontics
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• 제5권1호
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• pp.41-46
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• 1979

Silver amalgam has superior mechanical and physical properties, therefore it has been widely used in dental clinics. But we have found the silver amalgam failures frequently, its important reasons are fracture, fallen-out, tarnish, corosion and secondary caries etc. The author studied the compressive strength of silver amalgam. The author made the standardized specimen, prepared the Black's Class II cavity on chromecobalt alloy, and placed the three types of Unitek$^{(R)}$ pin (Type of pins are straight type, "ㄱ" bent type, "$\sqcap$" bent type pin. The compressive strength was measured by (Dynamic Strain Meter Shinko Co. Japan). The author took the following results by comparing with the control group, not used pin. 1) Compressive force of silver amalgam in straight type pin was $187.11{\pm}39.00kg$, $252.98{\pm}31.91kg$ in "ㄱ" type bent pin, $189.00{\pm}37.46Kg$ in "$\sqcap$" type bent pin, $172.33{\pm}28.07Kg$ in the control group. 2) The statistic significance of the compressive strnegth between each group showed that "ㄱ" type, bent pin is stronger than the control group or straight type pin. 3) There were no difference of significances between the control group and straight type pin, control group and "ㄱ" type bent pin and "$\sqap$" type bent pin, "ㄱ" type' bent pin "$\sqcap$" and type bent pin.