• Convergence Security Journal
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• v.19 no.4
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• pp.43-53
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• 2019

Recently, a number of military intranet infiltrations suspected of North Korea have been discovered. There was a problem that a vulnerability could occur due to the modification of user authentication data that can access existing military information systems. In this paper, we applied mutual verification technique and API (Application Programming Interface) forgery / forgery blocking and obfuscation to solve the authentication weakness in web browsers that comply with FIDO (Fast IDentity Online) standard. In addition, user convenience is improved by implementing No-Plugin that does not require separate program installation. Performance tests show that most browsers perform about 0.1ms based on the RSA key generation rate. In addition, it proved that it can be used for commercialization by showing performance of less than 0.1 second even in the digital signature verification speed of the server. The service is expected to be useful for improving military information system security as an alternative to browser authentication by building a web secure storage.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.436-442
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• 2013

Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, the feasibility of industry application was determined by analyzing the mechanical properties of weld region for a specimen of tube-to-tube shape for excavator hose nipple with friction welding, and optimized welding variables were suggested. In order to accomplish this object, friction heating pressure and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. An acoustic emission(AE) technique was applied to evaluate the optimal friction welding conditions nondestructively. AE parameters of accumulative count and event were analyzed in terms of generating trend of AE signals across the full range of friction weld. The typical waveform and frequency spectrum of AE signals which is generated by friction weld were discussed. From this study the optimal welding variables could be suggested as rotating speed of 1300 rpm, friction heating pressure of 15 MPa, and friction heating time of 10 sec. AE event was a useful parameter to estimate the tensile strength of tube-to tube specimen with friction weld.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.95-95
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• 2010

자동차 산업에서 차체를 성형하는 프레스 금형 산업은 꾸준히 증가하고 있는 자동차 생산대수와 함께 성장해가고 있으며, 자동차 산업의 국제 경쟁이 심해지고 소비자들의 요구가 다양해짐에 따라 신제품 개발주기에 발맞추어 금형의 제작에도 단납기 및 비용절감을 위한 노력과 제품의 품질 향상을 위해 신기술, 신공법이 적용되고 있다. 한편 자동차 차체를 제작하는 프레스 금형가공은 박판소재를 원하는 형상으로 제작하는 공정으로써, 프레스의 상 하 운동을 이용하여 강판을 성형한다. 이러한 금형의 형태는 곧 자동차 차체 제품의 형태를 완성하므로 제품을 성형하는 도중에 금형과 소재의 마찰에 의해 금형의 마모나 마멸이 발생하여 제품의 품질을 저하시킬 우려가 있다. 따라서 금형의 내마모성 및 수명을 향상시키기 위한 방안들 중 표면경화처리가 행해지고 있으며, 그중 공정 속도가 빠르고 국부적인 열처리가 가능한 레이저 표면처리 방법이 많은 관심을 받고 있다. 본 연구에서는 이러한 금형의 성질을 향상시키기 위해 고출력 다이오드 레이저를 이용하여 프레스 금형공정 중 드로잉(drawing) 공정에의 적용을 위한 표면경화처리를 실시하였다. 최대출력 4.0kW의 다이오드 레이저를 사용하였으며, 6축 외팔보 로봇에 열처리용 광학계를 장착하여 열처리를 실시하였다. 또한 광학계 부근에는 적외선 온도센서가 부착되어있어 열처리시 시험편의 표면온도를 실시간으로 측정할 수 있도록 구성되어져있다. 시험편은 금형재료용 구상흑연 주철인 FCD550 소재를 사용하였으며, 공정변수에 따른 열처리 특성을 파악하고, 그 경화특성을 평가하였다. 실험 결과, FCD550 소재의 표면 열처리시 레이저 출력 3.5kW, 빔 이송속도 3mm/sec에서 최적의 열처리 특성을 나타내었으며, 이때의 최고 경도는 930Hv을 나타내며 모재에 비해 경도가 3배 정도 상승하는 우수한 경화특성을 보였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.20-25
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• 2013

Ultrasonic methods are widely used to degradation assessment. Remaining-life cycle of metal can be estimated by ultrasonic parameters because ultrasonic velocity and attenuation are affected by change of material properties with accumulated fatigue in the metal. Therefore, in this study, we will estimate overall change of material properties by 2D C-scan image. Fatigued aluminum alloy 6061-T6 samples from 0 to 85% were prepared for evaluating fatigue life cycle. Also, degraded image of materials using attenuation is proposed to estimate degree of material degradation for determining degraded area of fatigued samples. Finally, we will predicts process pf degradation with measured attenuation of fatigued aluminum alloy 6061-T6 samples.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.471-482
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• 2015

Recently commercialized network are getting more and more popular, bringing dramatic change to the market. We can predict the future of the E-commerce. The ongoing E-commerce and SNS （Social Networking Services）related E-commerce are increasing greatly both in Korea and China. This research tries to focus on Chinese consumers using E-commerce. The study has four findings. Firstly, the E-commerce consumers consider four factors including price, convenience, products and website, which affect the sellers' integrity. Secondly, E-commerce will affect sellers' integrity. Third, there are 4 factors which affect the sellers' integrity: service, price, products and the information. Fourth, the factors which affect the integrity of sellers are the value, happiness and practical. This study want to give some hints to the E-commerce in the overseas market in China.

• The KIPS Transactions:PartD
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• v.15D no.4
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• pp.549-556
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• 2008

Web-based Enterprise Intranet System is developed Object-oriented programming language and data management is constructed using RDBMS. Between Object-oriented programming language and RDBMS bring about "Object-Relational Impedance Mismatch" due to heterogeneous paradigm. To solve this kinds of problems commonly use the ORM Framework that it is converting data between incompatible type systems in databases and object-oriented programming languages, uses complex mapping metadata. It causes difficult to develop and maintain because of inflexible in changes. This paper proposed persistence framework that solve the existing complexity of ORM framework and has more flexible in evolution of database table. This persistence framework is unnecessary meta information that connecting with entity of database table and the objects, it offers users convenience of maintenance and it allows far more flexible and affordable systems to be built because of automatically code generation. The result of testing based on the proposed persistence framework with Hibernate, iBATIS, It is similar response time with iBATIS and it has more about three times faster than Hibernate. But iBATIS has problems of mass data processing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.12-22
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• 2016

Convenience and safety are the key words for the automotive driving and various sensor technologies have been studied for enhanced perception of driving environments. In frequency modulated continuous wave (FMCW) radar systems, single antenna is enough for range and velocity detection of multiple targets. Multiple array antenna is needed for estimating direction of arrival(DoA). Using DoA estimation algorithm in time domain as in the conventional systems, it is difficult to distinguish vehicles lie in the same angle. In order to facilitate the enhanced angle estimation, DoA estimation algorithm is applied in frequency domain. In this paper, the method for applying multiple signal classification(MUSIC) algorithm in frequency domain is suggested and the performance is analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4587-4592
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• 2013

GPS is recognized the essential method to obtain the best result in the sphere of earth science that is setting of International Reference Frame, decision of the rotation coefficient about the earth rotation axis, detection of the crustal deformation, and observation of the diastrophism by high precision positioning except for navigation, geodetic survey and mapping. Therefore, in this study, it was attempted to build an expert service that enables non-experts to use high-precision GPS data processing. As a result, an Precise Point Positioning Solution that can maximize user convenience simply by entering the minimum required information for GPS data processing was developed, and the result of Precise Point Positioning Solution using GPS data provided by National Geographic Information Institute was compared with result of ITRF.

• Journal of Korea Multimedia Society
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• v.10 no.5
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• pp.623-630
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• 2007

With the development in IT technology and with growing demands of users, a ubiquitous environment is being made. Because of individuals identification is important in ubiquitous environment, RFID, a technology used frequently. RFID, a technology that radio frequency identification, reader send signer, then tag provide user information. RFID has various strengths, such as high recognition rates, quick recognition speed, but Eavesdropping is possible and problem that user information is revealed happens. To solve this, study is proceeded with activity, but, because of low-cost passive tag is limited operation capability, usually used hash function and random number. Also updates value that is used to present session and uses in next session. Therefore, this scheme protects user privacy using random number. And this sheme can offer synchronization by creating variable value without updating value.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.326-344
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• 2020

Laccase was applied to improve the drying speed of urushi lacquer to confirm a potential use of laccase as an enzyme additive. As a result of applying laccase of lacquer and white-rot fungi, drying times for both Korean and Chinese specimens were reduced. All of the specimens to which laccase was applied were dried(set to touch) within 60 minutes from the start of the drying, and the drying rate was improved as the content ratio of laccase increased. In addition, although there were differences in hardening drying time between Korean and Chinese lacquers, it was confirmed that hardening drying took place even at room with temperature of 20 ± 2 ℃ and humidity of 55-60%. As a result of lacquer layer analysis of the dried specimens, the drying speed was improved when the content ratio of laccase to urushiol was 5:1, and there were no differences in chromaticity and adhesion, confirmed that the layers were stable. It was observed that the gloss of both Korean and Chinese lacquers were reduced when laccase was applied. However, according to the analysis of FT-IR and Py-GC/MS, the changes in components were not as sufficient to affect the physical properties. Thus, its applicability as an additive was confirmed.