• Journal of Welding and Joining
• /
• 제11권1호
• /
• pp.42-51
• /
• 1993

In this study, investigations were conducted in calculating parameters of elastic-plastic fracture mechanics using single specimen. The validity of these testing methods was judged by the confirmation of multiple specimen method of stop block test. The results were as follows: In order to measure a fracture toughness using the instrumented impact test, two general requirement must be considered; One, setting up proper impact velocity considered the effect of loading and the other, the necessity of low blow test for obtaining true energy by the compliance correction. It was possible to detect a crack initiation point by calculating the compliance changing rate from a load-defection curve. Criterion of a stable crack growth, $T_{mat}$ could be estimated by using key-curve method for a base metal. and combining Kaiser's rebound compliance with Paris-Hutchison's $T_{appl}$ equation for the brittled zone of welding heat affected.at affected.d.

• 한국IT서비스학회지
• /
• 제8권1호
• /
• pp.11-27
• /
• 2009

Recently, IPTV attracts great attention along with the digital convergence of communication and media technologies. This study examined critical factors on the consumer's continued use of the IPTV service. Based on the expectation-confirmation theory and the innovation diffusion theory, we derived nine key factors in the research model-relative advantage, compatibility, ease of use, image, diversity of contents, interactivity, monetary value, social influence, and user satisfaction. Using the partial least square method, we found that content diversity and compatibility have a significant indirect effect on the continued use of the IPTV service via user satisfaction, and user satisfaction and social influence also have a significant direct impact on the IPTV use. These findings not only provide practical insights on the consumer acceptance of new technology-converging services, but also help managers to plan their marketing strategies better.

• Environmental Engineering Research
• /
• 제12권1호
• /
• pp.16-20
• /
• 2007

Toxicity of metal plating wastewater was evaluated by using acute toxicity tests on Daphnia magna. To identify toxicants of metal plating wastewater, several manipulations such as solid phase extraction (SPE), ion exchange and graduated pH adjustment were used. The SPE test had no significant effect on baseline toxicity, suggesting absence of toxic non-polar organics in metal plating wastewater. However, anion exchange largely decreased the baseline toxicity by 88%, indicating the causative toxicants were inorganic anions. Considering high concentration of chromium in metal plating wastewater, it is thought the anion is Cr(VI) species. Graduated pH test showing independence of the toxicity on pH change strongly supports this assumption. However, as revealed by toxicity confirmation experiment, the initial toxicity of metal plating wastewater (24-h TU=435) was not explained only by Cr(VI) (24-h TU = 725 at $280\;mg\;L^{-1}$). Addition of nickel($29.5\;mg\;L^{-1}$) and copper ($26.5\;mg\;L^{-1}$) largely decreased the chromium toxicity up to 417 TU, indicating antagonistic interaction between heavy metals. This heavy metal interaction was successfully predicted by an equation of 24-h $TU\;=\;3.67\;{\times}\;\ln([Cu]\;+\;[Ni])\;+\;79.44$ at a fixed concentration of chromium.

• 한국엔터테인먼트산업학회논문지
• /
• 제5권1호
• /
• pp.65-72
• /
• 2011

본 연구의 주목적은 이러닝 서비스의 지속사용의도에 영향을 미치는 요인에 관하여 체계적인 분석을 수행하는 것이다. 이러한 연구목적을 달성하기 위하여 본 연구에서는 기본 분석틀로서 Bhattacherjee(2001)에 의해 제안된 후기수용 모델(PAM)을 도입하였다. 그리고 이러닝 서비스에서 사용자의 수용 후 행동을 파악해 보기 위하여 관련 선행문헌에 대한 종합적 고찰 결과를 토대로 콘텐츠 품질, 상호작용성, 기대충족, 지각된 사용용이성, 지각된 유용성, 만족, 지속사용의도 등 일곱 가지 연구변수를 도출하였다. 이러닝 서비스 이용 경험자를 대상으로 조사를 수행한 후, 연구모델에 관하여 공분산구조모델 분석기법을 통한 연구모델의 평가 및 가설검정이 이루어졌다. 본 연구의 분석결과를 요약해 보면 다음과 같다. 첫째, 이러닝 서비스의 콘텐츠 품질, 상호작용성, 기대충족 등 세 가지 특성요인이 지각된 유용성에 긍정적인 영향을 미치는 것으로 밝혀졌다. 둘째, 이러닝 서비스의 콘텐츠 품질, 상호작용성, 기대충족, 지각된 사용용이성 모두는 사용자 만족에 긍정적인 영향을 미치는 것으로 나타났다. 마지막으로, 지각된 유용성은 사용자 만족에 긍정적인 영향을 미치며, 지각된 유용성과 사용자 만족은 모두 지속사용의도에 긍정적인 영향을 미치는 것으로 밝혀졌다. 본 연구의 결과를 토대로 이러닝 서비스 제공자 및 관련분야 연구자에게 유의미한 시사점을 제공하였다.

• 한국산학기술학회논문지
• /
• 제14권7호
• /
• pp.3487-3494
• /
• 2013

최근 NFC 기술을 탑재한 스마트 기기를 이용하여 모바일 지급결제, 출입통제, 스마트 포스터와 같이 정보 제공 또는 광고에 관련된 응용 서비스가 제공되고 있다. 이에 따라 NFC 기술과 더불어 스마트 기기 시장은 더욱더 성장할 것으로 전망된다. 특히, 모바일 지급결제 서비스가 국내 외에서 더 활성화될 것으로 예상되고 있으며, 2012년 3월에는 모바일 지급결제를 위한 표준인 KS X 6928이 제정되었다. 모바일 지급결제 시스템은 사용자에게 편의성을 제공하지만 거래 정보를 전송하는 과정에서 데이터가 노출되는 등 다양한 보안 위협이 발생할 수 있기 때문에 인가되지 않은 제 3자에게 전송되는 데이터가 노출되지 않도록 암호화를 수행하는 것이 반드시 요구된다. 따라서 본 논문에서는 KS X 6928의 대면 거래와 비대면 거래에서 데이터를 암호화하는데 사용하는 세션키 생성 방식의 문제점을 분석하고 안전성을 향상시킬 수 있는 안전한 모바일 지급결제 시스템을 제안한다.

• 터널과지하공간
• /
• 제16권1호
• /
• pp.1-10
• /
• 2006

실제 암반에는 단층, 절리, 층리, 균열, 단열, 편리, 벽개 등의 불연속면이 많이 포함되어 있다. 따라서, 불연속면이 암반구조물의 거동을 좌우하고 있다. 암반구조의 복잡성으로 인해 사전에 예측 할 수 없었던 암반의 붕락이 발생하여, 붕락대책에 막대한 비용과 시간을 낭비하는 사례가 많다. 암반 불연속면의 복잡성을 사전 조사단계에서 충분히 파악하거나 대책을 수립하는 것은 어렵다. 최근 터널의 정보화 설계시공이 중요시되어지고 있다. 본 논문에서는 불연속성 암반에서의 터널의 신 정보화 설계시공법을 제안하고, 현지에서 관찰한 불연속면 정보를 근거로 하여 실제 터널현장에 적용했다. 실제 터널현장에 있어서, 터널의 신 정보화 설계시공법을 위해서 새롭게 개발한 수치해석 프로그램을 사용하여 정확한 키블럭 추출이 가능하였다. 사용하기 쉬운 사용자 인터페이스를 가지고 있는 본 컴퓨터 시뮬레이션 기법은 암반블럭의 안정성 계산뿐만 아니라 추가 보강대책공의 설계도 가능하다. 터널 굴착중에 키블럭을 확인하므로써, 제안한 신 정보화 설계시공법의 유효성에 대한 검증을 하였다.

• Asia pacific journal of information systems
• /
• 제23권4호
• /
• pp.1-28
• /
• 2013

Given that smartphone-based social network services (SNS), such as KakaoStory is now being widely used as a way for people to connect and communicate with each other, this study examines key factors leading to the continued use of SNS. People have been using PC-based SNS, such as Cyworld, for years are now using smartphone-based SNS, such as KakaoStory. KakaoStory developed by KakaoTalk has rapidly grown up as the largest smartphone-based SNS in Korea as smartphone penetration increases. It is more difficult for firms to maintain their current users over time in that alternative SNSs satisfying people's new needs are constantly emerging and evolving. In this sense, one of the most challenging issues for SNS firms is how to retain their current users in the long run. However, there are few empirical studies on this issue. Applying the IS continuance model proposed by Bhattacherjee [2001], this study explores key determinants of users' smartphone-based SNS continuance intention. The model suggests that perceived usefulness and user satisfaction are the key determinants of IS continuance intention. However, the model includes only the utilitarian value that users can obtain through the use of smartphone-based SNS, by considering perceived usefulness. Therefore, the study attempts to extend the IS continuance model by considering hedonic and social values simultaneously. More specifically, we consider subjective norms as social value that are proposed by the theory of reasoned action and the theory of planned behavior. We also consider perceived enjoyment as hedonic value that is emphasized as a key factor influencing users' behavior intention and actual behavior, particularly in the context of hedonic IS use. By considering the three values in our model simultaneously, we could offer a deeper understanding of smartphone-based SNS continuance. That is, this study could offer an explanation of how each value is associated with user satisfaction and SNS continuance intention. The customer value-satisfaction-loyalty model can strengthen the assertion that smartphone-based SNS continuance intention is determined by various different types of customer values, such as utilitarian, hedonic, and social ones. Moreover, the model provides a theoretical basis for the assertion that customer values lead to increased loyalty via customer satisfaction. In this regard, we theorize that SNS continuance intention is influenced by users' various values, namely perceived usefulness, perceived enjoyment, and subjective norms, via user satisfaction. To test the proposed research model and hypotheses, we conducted a partial least squares analysis using a total of 253 data collected on the users of smartphone-based SNS (i.e., KakaoStory). The key findings are as follows: First, it has been found that SNS continuance intention considerably depends on user satisfaction. Second, user satisfaction is determined by confirmation, perceived usefulness, and perceived enjoyment. Third, concerning the effects of the three values on SNS continuance intention, only perceived enjoyment regarded as hedonic value was statistically significant. That is, perceived usefulness considered as utilitarian value and subjective norms considered as social value had no effect on SNS continuance intention. Finally, our results indicate that confirmation increases perceived usefulness, perceived enjoyment, and user satisfaction. The results reconfirm the effectiveness of IS continuance model in predicting smartphone-based SNS continuance intention. Moreover, the results demonstrate that perceived enjoyment reflecting hedonic value is the most important predictor of SNS continuance intention. Therefore, it is imperative for firms to meet SNS users' hedonic value to retain them in the long run. Meanwhile, we could not find any empirical evidence to support the assertion that subjective norms are associated with user satisfaction and SNS continuance intention. The results lead us to conclude that when users have enough direct experience in SNS use, subjective norms have no effect on SNS continuance intention. Discussions and implications of the results are provided.

• The Journal of Advanced Prosthodontics
• /
• 제13권6호
• /
• pp.361-372
• /
• 2021

PURPOSE. To improve the clinical effects of complete denture use and simplify its clinical application, a digital complete denture restoration workflow (Functional Suitable Digital Complete Denture System, FSD) was proposed and preliminary clinical evaluation was done. MATERIALS AND METHODS. Forty edentulous patients were enrolled, of which half were treated by a prosthodontic chief physician, and the others were treated by a postgraduate student. Based on the primary impression and jaw relation obtained at the first visit, diagnostic denture was designed and printed to create a definitive impression, jaw relation, and esthetic confirmation at the second visit. A redesigned complete denture was printed as a mold to fabricate final denture that was delivered at the third visit. To evaluate accuracy of impression made by diagnostic denture, the final denture was used as a tray to make impression, and 3D comparison was used to analyze their difference. To evaluate the clinical effect of FSD, visual analogue scores (VAS) were determined by both dentists and patients. RESULTS. Two visits were reduced before denture delivery. The RMS values of 3D comparison between the impression made via diagnostic dentures and the final dentures were 0.165 ± 0.033 mm in the upper jaw and 0.139 ± 0.031 mm in the lower jaw. VAS ratings were between 8.5 and 9.6 in the chief physician group, while 7.7 and 9.5 in the student group; there was no statistical difference between the two groups. CONCLUSION. FSD can simplify the complete denture restoration process and reduce the number of visits. The accuracy of impressions made by diagnostic dentures was acceptable in clinic. The VASs of both dentists and patients were satisfied.

• 융합정보논문지
• /
• 제7권2호
• /
• pp.31-36
• /
• 2017

본 논문은 대량의 영상에서 특정 출연자가 나오는 영상부분을 탐색하여 재생하고자 한다. TV영상 프로그램에서 주인공이나 특정 장면을 탐색 하려면 영상을 플레이하거나 코너를 설정하여 시청한다. 기존 방식은 장면 탐색이나 코너별 시청시 수동으로 offset값을 설정 하여야만 한다. 그러나 본 논문에서 제안하는 방식은 주인공 얼굴을 학습 시킨후 영상인식으로 주인공을 찾고 주인공이 등장하는 장면으로 이동하여 영상을 재생 하게 된다. 특정 출연자에 대한 데이터는 크롤링 기법을 활용하여 추출 및 수집한다. 수집된 데이터를 기반으로 컨볼루셔널 뉴럴 네트워크 알고리즘을 사용하여 학습하고 이를 이용하여 성능 평가를 진행한다. 성능 평가는 드라마를 재생하면서 추출된 키 프레임에서 학습 된 특정 출연자를 추출, 판단하는 방법으로 정확도를 측정한다. 학습된 장면을 얼마나 빨리 그리고 정확하게 탐색 하는지 성능 확인결과 약 93%의 정확도를 확보하였다. 도출된 성능을 기반으로 특정 장면만을 시청하는 코너별 시청, 인물 탐색 및 상세정보 retrieval 등 영상서비스에 응용 하고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제18권7호
• /
• pp.1968-1985
• /
• 2024

At present, the world is witnessing a rapid change in all the fields of human civilization business interests and goals of all the sectors are changing very fast. Global changes are taking place quickly in all fields - manufacturing, service, agriculture, and external sectors. There are plenty of hurdles in the emerging technologies in agriculture in the modern days. While adopting such technologies as transparency and trust issues among stakeholders, there arises a pressurized necessity on food suppliers because it has to create sustainable systems not only addressing demand-supply disparities but also ensuring food authenticity. Recent studies have attempted to explore the potential of technologies like blockchain and practices for smart and sustainable agriculture. Besides, this well-researched work investigates how a scientific cum technological blockchain architecture addresses supply chain challenges in Precision Agriculture to take up challenges related to transparency traceability, and security. A robust registration phase, efficient authentication mechanisms, and optimized data management strategies are the key components of the proposed architecture. Through secured key exchange mechanisms and encryption techniques, client's identities are verified with inevitable complexity. The confluence of IoT and blockchain technologies that set up modern farms amplify control within supply chain networks. The practical manifestation of the researchers' novel blockchain architecture that has been executed on the Hyperledger network, exposes a clear validation using corroboration of concept. Through exhaustive experimental analyses that encompass, transaction confirmation time and scalability metrics, the proposed architecture not only demonstrates efficiency but also underscores its usability to meet the demands of contemporary Precision Agriculture systems. However, the scholarly paper based upon a comprehensive overview resolves a solution as a fruitful and impactful contribution to blockchain applications in agriculture supply chains.