• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.265-267
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• 2011

저온 대기압 플라즈마는 21세기에 들어 생의학 분야에 이용될 수 있는 새로운 도구로서 많은 관심을 받고 있다. 대기압 플라즈마는 고가의 진공 장비를 필요로 하지 않고 저전력 구동이 가능하기 때문에 저비용 구동이 가능하고 방전 장치와 전력공급 장치의 소형화에 매우 유리하다. 특히 저온 대기압 플라즈마는 고온의 전자와 저온의 이온 입자가 공존하는 열적 불평형(thermal non-equilibrium) 상태에 있기 때문에 플라즈마의 저온 특성은 유지하면서도 (${\sim}30^{\circ}C$) 물리/화학적 반응성은 매우 높아 그 응용 분야가 매우 넓다. 플라즈마의 다양한 생의학 분야 응용 가운데 세포의 사멸 유발 또는 생장 촉진, 살균/멸균, 지혈, 상처 치유 등에 저온 대기압 플라즈마가 매우 뛰어난 효능을 보인다는 것이 국내외의 다양한 연구를 통해 밝혀지고 있다 [1]. 20 kHz 정현파로 구동되는 플라즈마 장치를 이용한 암 세포 제거 실험에서 플라즈마 처리 효과를 증대시키기 위해 항체-금나노입자 중합체를 암 세포에 주입시켰다 (그림 1(a)). 그 결과 세포의 사멸율은 74%로서 플라즈마 또는 플라즈마-금나노입자만을 처리한 경우에 비하여 사멸율이 매우 높게 나타났다 (그림 1(b)). 이를 통해 암세포 선택성을 가진 항체-금나노입자 중합체와 플라즈마 처리 기술을 융합한 암 세포의 선택적 사멸 유발 기술의 개발 가능성이 열렸다. 또한 플라즈마 처리를 통해 일어나는 세포의 자멸사 기작이 Cytochrome C의 방출 이후 이어지는 Caspase-3의 활성화 경로와 관계가 있음이 밝혀졌다 (그림 1(c)). 치아 미백은 최근 부상하고 있는 저온 대기압 플라즈마의 새로운 응용 분야이다 [5-6]. 대기압에서 동작하는 헬륨 플라즈마 제트를 미백제(과산화수소)와 함께 발치된 치아에 적용하였을 때 (그림 2(a)) 미백제만을 사용하였을 경우에 비해 치아의 색상 변화가 2배 이상 크게 나타나는 것을 확인하였다 (그림 2(b)). 이처럼 최근 그 범위가 크게 넓어지고 있는 저온 대기압 플라즈마의 생의학 응용 기술의 최적화를 위해서는, 다양한 생의학 응용 분야에 따라 요구되는 플라즈마의 특성 및 응용별 기저 기 작에 대한 이해와 연구가 필요하다.

• Human Ecology Research
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• v.52 no.4
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• pp.429-441
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• 2014

The use of smartphones has grown rapidly over a short period of time, particularly for commuting news search, smart banking, and social networking services, and has had a significant impact on the pattern of contemporary life. Further, a wide range of applications are downloaded on to smartphones. This has also led a considerable number of complaints regarding these applications. In this study, we focus on the levels of dissatisfaction that users experience with smartphone applications and their effects on consumer complaint behavior along with the moderating effects of the complaint handling process and attribution. The aim of this study is to verify whether the following hypothesis--2 (low/high dissatisfaction level of smartphone applications)${\times}2$ (poor/excellent complaint handling process)${\times}2$ (internal/external consumer attribution)--is in accordance with the betweengroup design to build a factorial design experiment. The results of this study are as follows. First, the consumer's tendency to complain significantly influenced their dissatisfaction level. Second, consumer complaint behavior is modulated by the complaint handling process. Third, the external-attribution tendency of consumers was found to lead to more dissatisfaction than the tendency for internal attribution.

• Proceedings of the Technology Innovation Conference
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• 2009.02a
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• pp.3-24
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• 2009

본 논문은 온라인 커뮤니티를 통해 사용자들이 정보교류와 의사소통을 활발히 전개하여 사용자혁신 (User Innovation)을 촉진하는 사례들과 이와 관련된 현안 이슈들, 그리고 기업의 사용자혁신 활용 전략을 다루고 있다. 특히 인터넷의 보급과 확산을 통해 사용자들이 온라인 커뮤니티를 형성하고 상호 교류할 수 있는 장이 마련되어 사용자혁신이 더욱 활성화 될 수 있으므로, 휴대기기 산업에서 이러한 사례를 발굴하여 분석하였다. 특히 본 연구에서는 MP3 플레이어 산업에서 기업이 온라인 커뮤니티를 통해 고객정보를 어떻게 획득/처리/활용하는지, 그리고 스마트폰인 블랙잭 제품에서 어떤 과정을 통해 사용자혁신이 이루어지는 지를 사례연구 하였다. 본 연구의 결과는 1)온라인 커뮤니티에서 사용자의 역할과 (정보공유, 아이디어 창출, 문제해결, 정보취합, 제품테스트, 사용의견 제시, 제품홍보 등) 기업의 대응전략, 2)기업과 고객간 커뮤니케이션 패턴 (질문/불평/사용후기 및 피드백/시제품/공지 등) 특성, 3)온라인 커뮤니티 내에서 사용자간 커뮤니케이션 패턴과 현안, 4)온라인 커뮤니티 활성화를 통한 신제품개발 촉진방안 등으로 구분하여 제시되었다. 마지막으로 이러한 사용자혁신 사례를 바탕으로, 사용자혁신을 촉진하고 신제품개발과정에서 사용자의 참여를 강화할 수 있는 정책적 함의를 정리하였다. 특히 개방형 혁신이 강조되는 상황에서 사용자혁신은 개방형 혁신의 한 형태도서도 의미가 있으며, 향후 더 많은 사례연구와 실증분석이 요구된다.

• The Journal of the Acoustical Society of Korea
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• v.15 no.6
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• pp.52-58
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• 1996

Using the acoustic resonances and oscillatory pulsations considered as the branch of wave technologies, the concept of the acoustic resonance diffusers for waste water treatment which maximize the oxygen transfer efficiency in gas-liquid two phase medium have been proposed, and studies for the principles and performance tests were accomplished. Besides, the design concepts for the low pressure Helmholtz resonator, cylinder and annular type reflection resonator and combined type resonance system have been implemented. The acoustic resonance energy which can speed up the mass transfer process increase the oxygen transfer efficiency, and periodic pulsations generated from the instability of air jet from nozzle make very small air bubbles. Then, the annular type jet resonator(AJR) applying these two principles successfully was evalulated as the most promising device and also the efficiency showing $20{\sim}30%$ better than conventional diffusers has been verified experimentally.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.386-395
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• 2010

Widespread deployment of infrastructure WLANs has made Wi-Fi an integral part of today's Internet access technology. Despite its crucial role in affecting end-to-end performance, past research has focused on MAC protocol enhancement, analysis, and simulation-based performance evaluation without sufficiently considering a misbehavior stemming from capture effect. It is well known that the capture effect occurs frequently in wireless environment and incurs throughput unfairness between nodes. In this paper, we propose a novel Fair MAC algorithm which achieves fairness even under physically unfair environment. While satisfying the fairness, the proposed algorithm maximizes the system throughput. Extensive simulation results show that the proposed Fair MAC algorithm substantially improves fairness without throughput reduction.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.5
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• pp.459-466
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• 2000

A new control method for precision robust speed control of a PMSM(Permanent Magnet Synchronous Motor) using load torque observer is presented. Using this system, we can more precisely evacuate of vestibular function. Until now a rotating chair system, so called 2D-stimulator, which has vertical rotate axis is used to make dizziness. However, an inclined rotating chair system witch is called 3D-stimulator is needed to obtain the precise dizziness data. This 3D-stimulator include unbalanced load caused by unbalanced center of mass. In this case, new compensation method is considered to obtain robust speed control using load torque observer. To reduce the effect of this disturbance, we can use dead-beat observer that has high gain. The application of the load to torque observer is published in for position control. However, there is a problem of using speed information such as amplifying effect of noise. Therefore, we can reduce a noise effect by moving average process. The experimental results are depicted in this paper to show the effect of this proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.1110-1116
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• 2017

Depending on the operating characteristics, track circuit is installed for the purpose of direct or indirect control of the signal device, point switch machine and other security device. These are mainly used for train detection, transmission of information, broken rail detection and transmission of return current. Especially, the return current is related to signal system, power system and catenary line, and track circuit systems. It is one of the most important component shall be dealt for the safety of track side staff and for the protection of railway-related electrical system according to electrification. Therefore, an accurate analysis of the return current is needed to prevent the return current unbalance and the system induced disorder and failure due to an over current condition. Also, if the malfunction occurred by the return current harmonics, it can cause problems including train operation interruption. In this paper, we presented measurement and analysis method at return current and it's harmonics by high speed train operation on the honam high speed line.

• Journal of the Korean Society for Computer Game
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• v.31 no.4
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• pp.157-166
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• 2018

Communication between customers and service providers is an important issue at sites where various businesses and transactions take place. In particular, the ability to solve problems quickly and accurately when a problem arises and when an inquiry is received is directly linked to trust in the site. In this paper, we propose a method of handling complaints and inquiries of site users by using chatbot technology on talent market platform site. First, we implemented chatbot that can communicate with the inquirers in real time, so that users can use the site usage and word search functions. For various errors and problems of the site which can not be defined by a few words or sentences, I have specified an error code and database it. Users of the site were able to contact chatbot with the error code that was output when an error occurred and get the corresponding response in real time. The chatbot implemented in this study provided a satisfactory experience because that was able to provide quick and accurate answers to users who experienced errors or inquiries when using the site. This will have a positive impact on the credibility and favorability of the site over the long term, and will help reduce manpower and time costs for error inquiries.

• Journal of Life Science
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• v.20 no.1
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• pp.103-112
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• 2010

Pemetrexed has demonstrated clinical activity in non-small cell lung cancer (NSCLC) as well as other solid tumors. It transports into the cells via reduced folate carrier (RFC) and is polyglutamated by folypolyglutamate synthetase (FPGS). Pemetrexed directly inhibits several folate-dependent enzymes such as thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT). We investigated the effects of genetic variations and the expression of RFC, FPGS, TS and DHFR enzymes on drug sensitivity to pemetrexed in NSCLC cells. Polymorphisms in RFC, FPGS, and DHFR were genotyped in four NSCLC cells - A549, PC14, HCC-1588, and H226. Real-time RT-PCR and Western blot was performed to evaluate mRNA transcripts and protein of these genes. The cytotoxicity of pemetrexed was measured by SRB assay. In PC14 and H226 cells, increased mRNA expressions of RFC and FPGS were associated with higher cytotoxicity to pemetrexed. 2R/2R genotype of TS and its increased mRNA expression were associated with drug resistance to pemetrexed in A549 cells, whereas 3R/3R genotype in TS with decreased mRNA expression was associated with higher sensitivity in H226 cells. After pemetrexed treatment, an inverse change of DHFR mRNA and protein expression was found. The strongest linkage disequilibrium (LD) was discovered between-1726C>T and -1188A>C SNP of DHFR gene. Our findings suggest the cytotoxic effect of pemetrexed may be associated with genetic polymorphisms and the expression level of genes involved in pemetrexed metabolisms in NSCLC cells.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.6
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• pp.744-757
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• 2012

This study was designed to obtain basic data for the globalization of Korean food and the expansion of food exports through contract foodservices. A survey of dietary habits and attitudes toward school foodservices was given to students in three American international schools served by a domestic contract foodservice management company located in Seoul and Gyeonggi area. The results showed an average of three meals taken daily 3.39 times for male students and 2.95 times for female students and the time required for a meal was about 24~26 minutes. The average breakfast frequency was 5.10 times(4.59 times for male students and 5.35 times for female students) and many students reported skipping breakfast due to a lack of time. The average weekly frequency of dining out was 1.78 times(2.15 times for male students and 1.60 times for female students). In all schools, irrespective of gender and grade, students responded that a desire for snacking was 'why they want to have cookies', and snacking hours were frequently listed as 'between noon and evening'. Many also responded that an unbalanced diet is the reason some snacks are 'not to their taste'. Overall, students were highly satisfied with the foodservice menu, although there was a significant difference in what was considered proper food temperature, proper food seasoning, suitable amounts of food, and freshness of food. Male and female students were specifically highly satisfied with the 'freshness of food materials' and 'variety of menu' respectively. Overall, all students were highly satisfied with the foodservice, including the 'cleanliness of tables and trays'.