• Korean journal of applied entomology
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• v.35 no.3
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• pp.238-242
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• 1996

The second instar milkweed bugs, Oncopeltus fasciatus were exposed to the residue of 6-methoxy-7-ethoxy-2, 2- dimethylchromene(or 7-ethoxy precocene 11, 7-EP-11) with one, two, or four different kinds of synergist(s) deposited as a residue on 9 cm diameter petri dishes. The anti juvenile hormone analog, 7-EP-I1 yielded a 50% effectiveness concentration at 1.18 wg/cmZ. The concentration of 7-EP-I1 and R020-9747 combined gave 0.084 ~*g/cm', as much 14 times more potent than with 7-EP-I1 alone. Most of the other synergists, including geraniol, 4-chalcone oxide, isosafrole, and piperonyl butoxide however, showed comparatively low level synergism with 1.0-4.3 times, depending upon the combinations of the synergist(s). The obtained results were considered that R020-9747, an analog of benzopyran with similar structure to that of 7-EP-I1 inhibited selectively the insect monooxygenase oxidative defense mechanism, in the body except for corpora allata because general antioxidants of piperonyl butoxide, isosafrole, and 4-phenyl chalcone oxide showed relatively mild synergism.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11A
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• pp.831-843
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• 2009

In this paper, we propose a new adaptive cooperation scheme with multi-relay nodes which achieves higher performance and spectral efficiency than that of some conventional cooperative schemes. The relay-selection is applied to choose the most potential relay among K ones. Afterward, the instantaneous signal-to-noise ratio (SNR) differences between S-D, S-R and R-D channels are considered for adaptive selection between the direct and the cooperation transmission strategy. In the proposed adaptive protocol, if the direct link is of high quality, the source will transmit to destination directly with all power consumption. Otherwise, the source broadcasts the signal with a lower power and requires the help of the chosen relay if it decodes correctly, else the source will transmit again with remaining power. Firstly, the spectral efficiency is derived by calculating the probability of each mode. Subsequently, the BER performance for the adaptive cooperation scheme is analyzed by considering each event that one of K relays is selected and then making the summation of all. Finally, the numerical results are presented to confirm the performance enhancement offered by the proposed schemes.

• Journal of Technology Innovation
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• v.19 no.2
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• pp.153-184
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• 2011

This paper investigates what kind of technological partner firms want to cooperate with in terms of partner location. Two geographical factors are considered. One is geographical proximity, given the tradeoff between the effectiveness of knowledge spillovers in proximity and diverse knowledge absorption from geographically distant partners. The other is how many other firms are co-located with potential partners because it is known that clustering regions can create more technological outputs. Analysis on 2008 Korea Innovation Survey data finds that partner proximity is the single most important factor in choosing a cooperation partner. While firms that are located in a region crowded with related industries prefer proximate partners, others that are surrounded by unrelated industries are more likely to cooperate with distant partners. The findings suggest that geographical proximity matters in partner selection because it not only stimulates knowledge spillovers but also reduces costs involving R&D cooperation such as monitoring costs and information costs. Moreover, firms take into consideration both the benefits and risks of clustering regions. If there are so many unrelated firms that they create agglomeration diseconomies such as congestion costs and unintentional knowledge leakages, firms are more likely to try to find their cooperation partners in other regions.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.563-565
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• 2003

최근 클러스터에 대한 연구는 내용 기반 클러스터의 부하 분배와 캐시 정책에 집중되고 있다. 본 논문에서는 웹 서비스의 고가용성 및 확장성을 제공하는 클러스터 환경에서 힌트 기반 협력적 캐싱의 캐시 적중률을 향상시키기 위해 기존의 DFR 기법을 개선하였다. 서비스 접근 확률을 이용하여 주 복사본과 종속 복사본을 선택적으로 제거하는 메모리 교체 방법을 제시하였으며, DFR 방식과 성능을 비교, 분석한 결과 DFR 방식보다 적은 디스크 접근률을 얻을 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.39-47
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• 2012

As a scheme to efficiently reduce the effects of multipath fading in next generation wireless communication systems, cooperative communication systems have recently come into the spotlight. Since these cooperative communication systems use cooperative relays with diverse fading coefficients to transmit information, having all relays participate in cooperative communication may result in unnecessary waste of resources, and thus relay selection schemes are required to efficiently use wireless resources. In this paper, we propose an efficient relay selection scheme through self-learning in cooperative wireless networks using Q-learning algorithm. In this scheme, we define states, actions and two rewards to achieve good SER (Symbol Error Rate) performance, while selecting a small number of cooperative relays. When these parameters are well-defined, we can obtain good performance. For demonstrating the superiority of the proposed Q-learning, We compared the proposed scheme with Q-learning and a relay selection scheme with a mathematical analysis. The simulation results show that, compared to a scheme that obtains optimum relays through a mathematical analysis, the proposed scheme uses resources efficiently by using smaller numbers of relays with comparable SER performance. According to these simulation results, the proposed scheme can be considered as a good attempt for future wireless communication.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.815-822
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• 2010

Two-way relaying scheme based on relay selection can not only achieve higher rate but also get the selection diversity gain according to the number of relays. However the scheme can not achieve combining gain because it does not consider the direct link between users. In this paper, we propose, with multiple relays, opportunistic cooperative two-way relaying scheme and incremental cooperative two-way relaying scheme which can achieve both selection diversity gain and combining gain. Simulation results show that proposed scheme outperform the conventional scheme by achieving both combining gain and selection diversity gain according to the number of relays.

• Management & Information Systems Review
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• v.36 no.2
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• pp.187-206
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• 2017

This study empirically investigated the direct and indirect effects of inter-organizational relationships control mechanisms (IRCM; prudent partner selection and complex contract) on the decrease of inter-organizational risks (i.e., relational risk and performance risk). The empirical results showed that prudent partner selection has a positive impact on the degrees of inter-organizational cooperation and the levels of inter-organizational information flow. The effects of complex contract on the inter-organizational cooperation and information flow were not significant. In the results of the decrease of inter-organizational risks, it was observed that inter-organizational cooperation has significant positive effects on the decrease of both relational risk and performance risk. It was found that partner selection only influences the decrease of performance risk. The impact of inter-organizational information flow on the decrease of inter-organizational risks was not statistically significant. The indirect effects of IRCM on the decrease of performance risk through inter-organizational cooperation were also empirically demonstrated. The significant impact of inter-organizational cooperation on the decrease of risks implies that high levels of collaborations among employees decrease the risk of opportunistic behavior as well as the possibility of low degrees of performance through cooperative efforts. According to the results of the effects of risks on supply-chain performance, only the impact of performance risk was negatively significant. This result points out that the low levels of performance cause delays in delivery and product launch, deterred production and delayed market response, and these deteriorated managerial activities necessarily decrease the degrees of supply-chain performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5C
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• pp.276-285
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• 2011

In this paper, we propose new cooperative precoder selection technique for interference limited MIMO networks. Our proposed method gives weighting to precoders in the codebook according to each precoder's performance priority. By applying our proposed method to precoder selection sequence, performance of entire system can be improved in terms of sumrate, stability, and feedback rate.

• 한국IT서비스학회:학술대회논문집
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• 2007.11a
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• pp.616-620
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• 2007

전자상거래에서 사용되고 있는 추천시스템은 사용자들의 프로파일과 이들의 정보를 바탕으로 사용자가 선호할 만한 아이템을 추천한다. 추천시스템에서 널리 사용되고 있는 협력적 필터링 방식은 사용자들 사이의 선호도 평가치를 비교하여 유사 사용자를 선택하고, 아이템에 대한 유사 사용자의 선호도 평가치를 기반으로 하여 추천하고자 하는 아이템에 대한 사용자의 선호도를 예측하는 것이다. 하지만 사용자의 선호도가 적은 데이터로 인한 희소성 문제는 추천시스템의 성능을 저해하는 요인으로 작용하고 있다. 이러한 희소성의 문제는 선호도 평가 자료에 나타난 아이템들의 총수에 비하여 사용자가 선호한 아이템의 수가 아주 적기 때문에 발생하며, 새로운 사용자의 경우에는 아이템에 대한 선호도 평가치가 없어 유사 사용자를 선택할 수가 없어 나타나며 심한 경우에는 아이템을 전혀 추천할 수 없게 된다. 이리할 추천 시스템의 희소성문제를 해결차기 위한 방법은 희소성이 높은 데이터들에 대한 희소성을 감소시키는 것이다. 따라서 본 논문에서는 아이템에 대한 희소성을 조사하여 협력적 필터링에서 희소성 아이템이 MAE에 미치는 영향을 분석하였다. 그리고 희소성 문제를 완화하여 예측 정확도를 높이기 위한 방법으로 선호도가 적은 아이템에 대해 희소성을 최소화하는 연구와 이에 따라 희소성과 MAE의 값을 개선하는 방법을 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.472-474
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• 2001

웹 기반의 쇼핑몰 사이트의 수가 많아지고 그 이용량이 증가하면서, 차별화된 고객 서비스를 위해 다양한 데이터마이닝 기술들이 적용되고 있다. 특히 고객의 취향에 부합하며 그의 필요를 만족하는 상품을 고객에게 제안하는 추천 시스템을 위해 정보 필터링(information filtering) 알고리즘들이 사용되고 있다. 많은 추천 시스템들은 고객들이 상품에 대해 부여한 선호도 정보를 기반으로, 현재 사용중인 고객에게 그와 취향이 비슷한 고객들이 선택했으며, 아직 그가 선택한 적이 없는 상품을 추천하는 협력적 필터링(collaborative filtering) 방법을 사용하고 있다. 본 연구에서는 보통의 협력적 필터링 방법에 내용기반 필터링(content-based filtering) 방법을 적용하고, 고객의 상품에 대한 선호도 점수를 자동으로 계산할 수 있도록 하는 방법을 제안하여 적용함으로써 협력적 필터링 방법을 개선하였다.