• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1375-1381
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• 2018

In this paper, we studied coatings of the DLC thin film for improving loosening torque of dental implant screw. We used a filtered arc ion plating process which can realize the most dense DLC layer by coating the DLC thin film on the surface of the dental abutment screw. It showed both hardness comparable to diamond and low friction coefficient similar to graphite, and to improve the loosening phenomenon by increasing the screw tightening force Cr/CrN, Ti/TiN or Ti/TiN/Cr/CrN buffer layers were deposited for 5 to 10 minutes to improve the adhesion of the DLC thin film to the surface of the Ti (Gr.5), and then the DLC thin film was coated for about 15 minutes. As a result, the Cr/CrN buffer layer exhibited the highest hardness of 29.7 GPa, the adhesion of 18.62N on average, and a very low coefficient of friction of less than 0.2 as a whole. And we measured loosening torque after one million times with masticatory movement simulator. As a result, the values of the coated screw loosening torque were clearly higher than those of the uncoated screw. From this, it was found that the DLC coating was effective methods improving the loosening torque. In addition, it was confirmed that the cytotoxicity test and cell adhesion test showed high biocompatibility.

• Journal of Korea Multimedia Society
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• v.12 no.9
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• pp.1201-1209
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• 2009

Recently, the convergence of the telecommunications industry through the development of network media has brought along interactive data services in addition to the traditional broadcast services by providing direct connections between the users and the broadcasters. This can be easily achieved by the combination of existing network technology and multimedia technology, but in reality, as seen in the actual implementation of IPVT, it's difficult to provide satisfactory levels of service to users due to issues of network bandwidth and problems of streaming system. In particular, a network which is able to fully support Qos/QoE, and also a fast enough channel changing technology that is satisfactory to the user, are prerequisites for IPTV success. Therefore this thesis proposes a fast channel changing technique to delivery enhanced IPTV user experience. Recent IP set-top-boxes use only a small portion of the CPU to feed Ethernet packets to the hardware decoder and play them. Thus, by making IP set-top-boxes share cached channel information and content with each other, reducing the load on the server and enhancing the channel changing time is made possible.

• 한국어정보학회:학술대회논문집
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• 2016.10a
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• pp.181-185
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• 2016

최근 교육과정에서 학생들의 능력 평가는 단순 암기보다 학생들의 종합적인 사고력을 판단할 수 있는 서답형 문항을 늘리는 방향으로 변하고 있다. 그러나 서답형 문항의 경우 채점하는 데 시간과 비용이 많이 들고, 채점자의 주관에 따라 채점 결과의 일관성과 신뢰성을 보장하기 어렵다는 문제가 있다. 이런 점을 해결하기 위해 해외의 사례를 참고하여 국내에서도 서답형 문항에 자동채점 시스템을 적용하는 연구를 진행하고 있다. 본 논문에서는 2014년도에 개발된 '한국어 문장 수준 서답형 문항 자동채점 시스템'의 성능분석을 바탕으로 언어 처리 기능과 자동채점 성능을 개선한 2015년도 자동채점 시스템을 간략하게 소개하고, 각 자동채점 시스템의 성능을 비교 분석한다. 성능 분석 대상으로는 2014년도 국가수준 학업성취도평가의 서답형 문항을 사용했다. 실험 결과, 개선한 시스템의 평균 완전 일치도와 평균 정확률이 기존의 시스템보다 각각 9.4%p, 8.9%p 증가했다. 자동채점 시스템의 목적은 가능한 채점 시간을 단축하면서 채점 기준의 일관성과 신뢰성을 확보하는 데 있으므로, 보완한 2015년 자동채점 시스템의 성능이 향상되었다고 판단할 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.2
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• pp.81-89
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• 2001

Space systems are operating in a changing and uncertain space environment and are desired to have autonomous capability for long periods of time without frequent telecommunications from the ground station At the same time. requirements for new set of projects/systems calling for ""autonomous"" operations for long unattended periods of time are emerging. Since, by the nature of space systems, it is desired that they perform their mission flawlessly and also it is of extreme importance to have fault-tolerant sensor/actuator sub-systems for the purpose of validating science measurement data for the mission success. Technology innovations attendant on autonomous data validation and health monitoring are articulated for a growing class of autonomous operations of space systems. The greatest need is on focus research effort to the development of a new class of fault-tolerant space systems such as attitude actuators and sensors as well as validation of measurement data from scientific instruments. The characterization for the next step in evolving the existing control processes to an autonomous posture is to embed intelligence into actively control. modify parameters and select sensor/actuator subsystems based on statistical parameters of the measurement errors in real-time. This research focuses on the identification/demonstration of critical technology innovations that will be applied to Autonomous Spacecraft Health Monitoring/Data Validation Control Systems (ASHMDVCS). Systems (ASHMDVCS).

• Journal of KIISE:Databases
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• v.27 no.4
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• pp.549-561
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• 2000

In database management systems(DBMSs), partial rollback is a useful facility that cancels part of the executed operations upon user's requests without a total rollback. Many relational DBMSs(RDBMSs) provide this facility, However, object-orientccd DBMSs (OODBMSs) cannot utilize the previous recovery scl18lne of partial rollback usccd in (RDBMSs) since, unlike RDBMSs, they use a dual buffer consisting of an object buffer and a page buffer. Therefore, a new recovery scheme is required that rolls back the data efficiently in the dual buffer. We propose four partial rollback schemes in OODBMSs that use a dual buffer. We classify the proposed schemes into the single buffer based partial rollback scheme and the dual buffer based partial rollback scheme according to the number of buffers used for partial rollback processing. We further classify them into Uthe page buffer based partial rollback scheme, 2)the object buffccr based partial rollback scheme, 3)the dual buffer based partial rollback scheme using soft log, and 4)the dual buffer based partial rollback scheme using shadows. We evaluate the performance by mathematical analysis and experiments. The results show that the dual buffer based partial rollback scheme using shadows provides the best performance.

• Journal of Broadcast Engineering
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• v.14 no.4
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• pp.488-500
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• 2009

In this paper, we study on making a use of value-added services using DTV closed caption data. Note that Closed-Captioning service helps to bridge "digital divide" through extending broadcasting accessibility of a neglected class such as hearing-impaired person and foreigner. In Korea, DTV Closed Captioning standard was developed in June 2007, and Closed Captioning service should be provided by an enforcing law in all broadcasting services in April 2008. Here, we describe the method of extracting a caption data from MPEG-2 Transport Stream of ATSC-based digital TV signal and generating a caption file using the extracted caption data and time information. In addition, we present the segmentation method of broadcasting content using caption file. Experimental results show that implemented S/W tool provides the feasibility of the proposed methods and the usability of closed caption for a variety of data application service.

• Korean Management Science Review
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• v.32 no.4
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• pp.193-207
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• 2015

Government-funded research institutes (GRIs) have played a pivotal role in national R&D in Korea. To achieve desired goals of GRIs with the limited R&D budget, their performance along with time needs to be measured and compared so that appropriate R&D policies can be formulated and implemented. This study measures the dynamic performance of GRIs from the efficiency perspective using the window model of data envelopment analysis (DEA). DEA is a non-parametric approach to measuring the relative efficiency of decision-making units (DMUs) with multiple inputs and outputs, and the DEA window model can capture the dynamic changes in efficiency of DMUs during multiple periods. The relative efficiency of GRIs is measured from the two perspectives: R&D and R&BD. Patents, papers, technology transfers are selected as outputs for R&D while compensated technology transfers and technology royalty are employed as outputs for R&BD. This study measures and compares the two types of performance of 20 Korean GRIs under the control of National Research Council of Science and Technology during the period of six years from 2008 to 2013. The results are expected to provide fruitful implications for national R&D policy making.

• 한국어정보학회:학술대회논문집
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• 2017.10a
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• pp.309-313
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• 2017

개체명은 인명, 지명, 조직명 등 문서 내에서 중요한 의미를 가지므로 질의응답, 요약, 기계번역 분야에서 유용하게 사용되고 있다. 개체명 인식은 문서에서 개체명에 해당하는 단어를 찾아 개체명 범주를 부착하는 작업을 말한다. 개체명 인식 연구에는 개체명 범주가 부착된 개체명 말뭉치를 사용한다. 개체명의 범주는 연구 분야에 따라 다양하게 정의되므로 연구 분야에 적합한 개체명 말뭉치가 필요하다. 하지만 이런 말뭉치를 구축하는 일은 시간과 인력이 많이 필요하다. 따라서 본 논문에서는 개체명 사전 기반의 반자동 말뭉치 구축 도구를 제안한다. 제안하는 도구는 크게 전처리, 사용자 태깅, 후처리 단계로 나뉜다. 전처리 단계는 자동으로 개체명을 찾는 단계이다. 약 11만 개의 개체명을 기반으로 하여 트라이(trie) 구조의 개체명 사전을 구축한 후 사전을 이용하여 개체명을 자동으로 찾는다. 사용자 태깅 단계는 사용자가 수동으로 개체명을 태깅하는 단계이다. 전처리 단계에서 찾은 개체명 중 오류가 있는 개체명들은 수정하거나 삭제하고, 찾지 못한 개체명들은 사용자가 추가로 태깅하는 단계이다. 후처리 단계는 태깅한 결과로부터 사전 정보를 갱신하는 단계이다. 제안한 말뭉치 구축 도구를 이용하여 752개의 뉴스 기사에 대해 개체명을 태깅한 결과 7,620개의 개체명이 사전에 추가되었다. 제안한 도구를 사용한 결과 사용하지 않았을 때 비해 약 57.6% 정도 태깅 횟수가 감소했다.

• Environmental Analysis Health and Toxicology
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• v.30
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• pp.15.1-15.11
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• 2015

Objectives There has been a growing concern about the possible carcinogenic effects of the electromagnetic radiofrequency fields emitted from mobile phones. The purpose of this study was to investigate the association between mobile phone use and the development of gliomas in Korea. Methods Our study methods were based on the International Interphone study that aimed to evaluate possible adverse effects of mobile phone use. This study included 285 histologically-confirmed Korean patients 15 to 69 years of age, with gliomas diagnosed between 2002 and 2007 in 9 hospitals. The 285 individually matched controls were healthy individuals that had their medical check-up in the same hospitals. Unconditional logistic regression was used to calculate the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for use of mobile phones. Results For the entire group, no significant relationship was investigated between gliomas and regular use of mobile phones, types of mobile phones, lifetime years of use, monthly service fee, and the other exposure indices. Analyses restricted to self-respondents showed similar results. For ipsilateral users, whose the body side for usual mobile phone use match the location of glioma, the aORs (95% CIs) for lifetime years of use and cumulative hours of use were 1.25 (0.55 to 2.88) and 1.77 (0.32 to 1.84), respectively. However, the contralateral users showed slightly lower risk than ipsilateral users. Conclusions Our results do not support the hypothesis that the use of mobile phones increases the risk of glioma; however, we found a non-significant increase in risk among ipsilateral users. These findings suggest further evaluation for glioma risk among longterm mobile phone users.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.58
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• pp.237-263
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• 2013

Traditionally, a L/C (letter of credit) has been known as a relatively low risk method of payment. This is why L/C has been used in international trade. However, L/C has a number of weak points such as high cost, long processing time, and complicated documents. Using an electronic L/C is one way to solve those weak points. In Korea, there are two types of electronic L/C. One is the EDI (Electronic Data Interchange) based L/C and the other one is the XML (Extensible Markup Language) based L/C. The former, established in 1990's, is sent from banks to the beneficiary solely through VAN (Value Added Network, KTNET) operators. On the other hand the latter, started in 2005, is sent from banks to KFTC (Korea Financial Telecommunications & Clearings Institute) for management of the L/C balance, as well as to KTNET. So far, paper L/C and EDI based L/C have been used overwhelmingly instead of XML based L/C in spite of the aforesaid disadvantages. In this paper, the authors examined empirically why the users of electronic L/C were reluctant to use XML based L/C. The results are as follows. First, the users of paper L/C were more dissatisfied than the users of electronic L/C due to many factors such as cost, the time required, and information reuse. Second, the users who have more experience with XML based L/C wanted to adopt integrated management with EDI based L/C more than the users who had not experienced XML based L/C. Third, the users who had used more than one form of L/C wanted to adopt integrated management to EDI and XML based L/C more than the users who had only used one form of L/C. Therefore, the authority for electronic L/C should consider a change of the policy from the XML based electronic L/C oriented to integrated management of the various types of L/C.