인과지도에 기반한 미래 주파수공유 생태계 분석

송희석(Hee Seok Song),김태한(Taehan Kim) 한국데이타베이스학회 2013 Journal of information technology applications & m Vol.20 No.4

There is tremendous increasing demand on spectrum resource which is boosted by spread of cloud computing and M2M telecommunication as well as smart phone and tablet PC. Recently, spectrum sharing technology has drawn attention to the spectrum policy makers as a promising way to overcome limitation of scarce spectrum resource. To succeed in commercialization of spectrum sharing technology, it is necessary to prospect the future business ecosystem of spectrum sharing and develop appropriate policies and laws at the same time along with the advance of spectrum sharing technology. The purpose of this paper is to prospect future spectrum sharing ecosystem and analyze business ecosystem of spectrum sharing with casual loop map. With the causal map and system dynamics method, it is possible to analyze feedback loops which is not limited to linear thinking and build policies which optimize positive dynamics in business ecosystem of spectrum sharing.

소셜네트워크에서 신뢰의 전이성과 결합성에 관한 연구

송희석(Hee Seok Song) 한국데이타베이스학회 2011 Journal of information technology applications & m Vol.18 No.4

Trust prediction between users in social network based on the trust propagation assumes properties of transitivity and composability of trust propagation. But it has been hard to find studies which test on how those properties have been operated in real social network. This study aims to validate if the longer the distance of trust paths and the less the numbers of trust paths, the higher prediction error occurs using two real social network data set. As a result, the longer the distance of trust paths, we can find higher prediction error when predicting level of trust between source and target users. But we can not find decreasing trend of prediction error though the possible number of trust paths between source and target users increases.

페이스북 사용자간 내재된 신뢰수준 예측 방법

송희석(Hee Seok Song) 한국데이타베이스학회 2013 Journal of information technology applications & m Vol.20 No.2

Social network has been expected to increase the value of social capital through online user interactions which remove geographical boundary. However, online users in social networks face challenges of assessing whether the anonymous user and his/her providing information are reliable or not because of limited experiences with a small number of users. Therefore, it is vital to provide a successful trust model which builds and maintains a web of trust. This study aims to propose a prediction method for the interpersonal trust which measures the level of trust about information provider in Facebook. To develop the prediction method, we first investigated behavioral research for trust in social science and extracted 5 antecedents of trust : lenience, ability, steadiness, intimacy, and similarity. Then we measured the antecedents from the history of interactive behavior and built prediction models using the two decision trees and a computational model. We also applied the proposed method to predict interpersonal trust between Facebook users and evaluated the prediction accuracy. The predicted trust metric has dynamic feature which can be adjusted over time according to the interaction between two users.

시스템 다이내믹스를 이용한주파수 공유 생태계 활성화 정책대안 비교 분석 연구

송희석(Hee Seok Song),김재경(Jae Kyung Kim),김태한(Taehan Kim) 한국데이타베이스학회 2014 Journal of information technology applications & m Vol.21 No.4

인과지도에 기반한 주파수공유 생태계 활성화 정책 설계

송희석(Hee Seok Song),김재경(Jae Kyung Kim),김태한(Tae han Kim) 한국IT서비스학회 2014 한국IT서비스학회지 Vol.13 No.4

Demand of spectrum resource is tremendously increasing recently and this trend will continues in the future due to the wide spread of IT services based on cloud computing and Internet of Things technology and as well as smart devices. Recently, spectrum sharing technology has drawn attention to the spectrum policy makers as a promising way to overcome the shortage problem of scarce spectrum resource. To succeed in commercialization of spectrum sharing technology, it is necessary to prospect the future business ecosystem of spectrum sharing and develop appropriate policies and laws at the same time along with the advance of spectrum sharing technology. The purpose of this paper is to analyze casual relationships between enablers in future business ecosystem of spectrum sharing and propose policies to vitalize spectrum sharing ecosystem based on a system dynamics causal map proposed in the previous research. With the causal map and system dynamics method, it is possible to analyze feedback loops exist in the business ecosystem of spectrum sharing and build policies which optimize positive dynamics in business ecosystem of spectrum sharing. As a result, policy leverages were found in four areas; spectrum supply, spectrum demand, spectrum quality and technology, and spectrum transaction cost. For those policy leverages, 13 policies were identified and intervention timing for each policy was discussed. Finally, the promotion policies of government and market participants to vitalize spectrum sharing ecosystem were discussed.

반복 구매제품의 재구매시기 예측을 위한 다층퍼셉트론(MLP) 모형과 순환신경망(RNN) 모형의 성능비교

송희석(Hee Seok Song) 한국데이타베이스학회 2017 Journal of information technology applications & m Vol.24 No.1

Existing studies for recommender have focused on recommending an appropriate item based on the customer preference. However, it has not yet been studied actively to recommend purchase timing for the repurchase product despite of its importance. This study aims to propose MLP and RNN models based on the only simple purchase history data to predict the timing of customer repurchase and compare performances in the perspective of prediction accuracy and quality. As an experiment result, RNN model showed outstanding performance compared to MLP model. The proposed model can be used to develop CRM system which can offer SMS or app based promotion to the customer at the right time. This model also can be used to increase sales for repurchase product business by balancing the level of order as well as inducing repurchase of customer.

사회네트워크에서 사용자 행위정보를 활용한 퍼지 기반의 신뢰관계망 추론 모형

송희석(Hee Seok Song) 한국데이타베이스학회 2010 Journal of information technology applications & m Vol.17 No.4

We are sometimes interacting with people who we know nothing and facing with the difficult task of making decisions involving risk in social network. To reduce risk, the topic of building Web of trust is receiving considerable attention in social network. The easiest approach to build Web of trust will be to ask users to represent level of trust explicitly toward another users. However, there exists sparsity issue in Web of trust which is represented explicitly by users as well as it is difficult to urge users to express their level of trustworthiness. We propose a fuzzy-based inference model for Web of trust using user behavior information in social network. According to the experiment result which is applied in Epinions.com. the proposed model show improved connectivity in resulting Web of trust as well as reduced prediction error of trustworthiness compared to existing computational model.

유·무선인터넷 서비스의 경쟁관계 분석

송희석(Hee Seok Song),여재현(Jaehyun Yeo) 대한전자공학회 2004 대한전자공학회 학술대회 Vol.2004 No.12

모바일상거래 서비스의 저항요인

송희석(Hee Seok Song),김경철(Kyeong Cheol Kim) 한국전자거래학회 2006 한국전자거래학회지 Vol.11 No.2

이 연구에서는 모바일상거래 서비스를 대상으로 상대적 이점, 적합성, 복잡성, 지각된 위험, 더 좋은 제품에 대한 기대와 같은 혁신특성변수와 지각된 자기효능, 혁신성, 기존 제품에 대한 태도 등의 소비자특성 변수를 설명변수로 활용하여 모바일상거래 서비스 수용과정에서 소비자저항에 영향을 미치는 요인을 분석하였다. 추가적으로 이러한 영향요인들이 ‘지식-설득-결정’ (l집단), ‘설행-확신’(2집단)의 수용단계에 따라 어떻게 달라지는지를 실증 분석하였다. 다중회귀분석을 실시한 결과 상대적 이점, 지각된 자기효능, 지각된 위험, 기존 제품에 대한 태도가 모바일상거래 서비스 혁신저항에 영향을 미치는 주요 요인으로 나타났다. 수용단계별 분석에서는 상대적 이점, 지각된 위험, 기존 제품에 대한 태도는 l집단에서, 적합성, 복잡성, 자기효능은 2집단에서 혁신저항에 유의한 영향을 미치는 요인으로 나타났다. 이 연구는 모바일상거래 서비스뿐만 아니라 유사서비스인 휴대인터넷(Wibro), DMB 등의 신규 서비스의 소비자 수용과정에서도 저항요인을 사전에 파악하여 이를 극복하는데 시사점을 제공할 수 있을 것이다. This paper analyzes the resistance to mobile commerce services in consumer adoption process. Relative advantage, compatibility, perceived risk, complexity, self-efficacy, innovativeness and attitude for competing service have been chosen as independent variables. This paper also investigates on the significant factors which resist against adoption of mobile commerce service according to adoption phase. The results show that relative advantage, self-efficacy, perceived risk, attitude for competing service are significant factors to affect resistance to mobile commerce services. Relative advantage, perceived risk, attitude for competing service are significant resistance to mobile commerce services for consumers in before-adoption group and compatibility, complexity, self-efficacy are significant factors for consumers in after-adoption group. This study can be extended to new communication services such as Wibro and DMB to reduce resistances in early adoption phase.

ANFIS 기반 분류모형의 설계 및 성능평가

송희석(Hee Seok Song),김재경(Jae Kyeong Kim) 한국지능정보시스템학회 2009 지능정보연구 Vol.15 No.3

Fuzzy neural network is an integrated model of artificial neural network and fuzzy system and it has been successfully applied in control and forecasting area. Recently ANFIS(Adaptive Network-based Fuzzy Inference System) has been noticed widely among various fuzzy neural network models because of its outstanding accuracy of control and forecasting area. We design a new classification model based on ANFIS and evaluate it in terms of classification accuracy. We identified ANFIS-based classification model has higher classification accuracy compared to existing classification model, C5.0 decision tree model by comparing their experimental results.