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New Mathematical Model for Travel Route Recommendation Service
Intae Hwang(황인태),Heungseob Kim(김흥섭) 한국산업경영시스템학회 2017 한국산업경영시스템학회지 Vol.40 No.3
With the increased interest in the quality of life of modern people, the implementation of the five-day working week, the increase in traffic convenience, and the economic and social development, domestic and international travel is becoming commonplace. Furthermore, in the past, there were many cases of purchasing packaged goods of specialized travel agencies. However, as the development of the Internet improved the accessibility of information about the travel area, the tourist is changing the trend to plan the trip such as the choice of the destination. Web services have been introduced to recommend travel destinations and travel routes according to these needs of the customers. Therefore, after reviewing some of the most popular web services today, such as Stubby planner (http://www.stubbyplanner.com) and Earthtory (http://www.earthtory.com), they were supposed to be based on traditional Traveling Salesman Problems (TSPs), and the travel routes recommended by them included some practical limitations. That is, they were not considered important issues in the actual journey, such as the use of various transportation, travel expenses, the number of days, and lodging. Moreover, although to recommend travel destinations, there have been various studies such as using IoT (Internet of Things) technology and the analysis of cyberspatial Big Data on the web and SNS (Social Networking Service), there is little research to support travel routes considering the practical constraints. Therefore, this study proposes a new mathematical model for applying to travel route recommendation service, and it is verified by numerical experiments on travel to Jeju Island and trip to Europe including Germany, France and Czech Republic. It also expects to be able to provide more useful information to tourists in their travel plans through linkage with the services for recommending tourist attractions built in the Internet environment.
독립적인 MCS 레벨 선택 방식이 적용된 AMC-MIMO 결합 시스템의 성능 개선
김철성 ( Intae Hwang ),황인태 ( Kwang-wook Choi ),최광욱 ( Sang-jin Ryoo ),류상진 ( Kyung-hwan Lee ),이경환 ( Cheolwoo You ),유철우 ( Dae-ki Hong ),홍대기 ( Mingoo Kang ),강민구 ( Cheol-sung Kim ) 한국인터넷정보학회 2007 인터넷정보학회논문지 Vol.8 No.1
본 논문에서는 AMC-V-BLAST(Adaptive Modulation and Coding-Vertical-Bell-lab Layered Space-Time) 결합 시스템에 각 레이어 별로 공통적인 MCS(Modulation and Coding Scheme) 레벨을 적용한 경우와 독립적인 MCS레벨을 적용한 경우의 시스템 구조를 제시 후 성능을 관찰한다. 그리고 공통적인 MCS 레벨이 적용된 결합 시스템의 성능에 비하여 독립적인 MCS 레벨이 적용된 결합 시스템이 어느 정도의 전송률 향상이 있는가를 살펴본다. 실험결과, 독립적인 MCS 레벨이 적용된 경우가 레이어 별로 각 채널상태에 따라 최대한의 전송률을 얻기 위한 변조 및 코딩 방식이 선택되므로 공통 MCS 레벨을 적용한 경우에 비하여 전송률 성능이 우수함을 보였다. 특히, 약 7dB ~ 9dB SNR 구간에서 독립적인 MCS 레벨을 적용한 AMC-V-BLAST 결합 시스템의 경우가 공통적인 MCS 레벨을 적용한 경우에 비하여 약 700kbps의 전송률이 개선됨을 확인하였다. 또한, 수신다이버시티를 고려하며 MMSE 무효화 기법을 적용한 AMC-V-BLAST 결합 시스템의 경우 7dB ~ 9dB SNR 구간에 대하여 독립적인 MCS 레벨을 적용한 시스템과 공통적인 MCS 레벨을 선택한 시스템 간의 전송률 차이가 약 350kpbs 내외로 나타남을 확인할 수 있다. In this paper, we propose and observe a system that adopts Common-MCS (Modulation and Coding Scheme) level over all layer and Independent-MCS level for each layer in the combined AMC-V-BLAST (Adaptive Modulation and Coding-Vertical-Bell-lab Layered Space-Time) system. Also, comparing with the combined system using Common-MCS level, we observe throughput performance improvement in case of Independent-MCS level. As a result of simulation, Independent-MCS level case adapts modulation and coding scheme for maximum throughput to each channel condition in separate layer, resulting in improved throughput compared to Common-MCS level case. Especially, the results show that the combined AMC-V-BLAST system with Independent-MCS level achieves a gain of 700kbps in 7~9dB SNR (Signal-to-Noise Ratio) range against using Common-MCS level. In addition, the combined AMC-V-BLAST system using MMSEnulling method with receive diversity is verified that the difference of throughput between Independent MCS level system and common MCS level system in 7dB~9dB SNR is about 350kbps more or less.
Equal Gain Block Decomposition Methods for Multiuser MIMO Networks
( Insoo Hwang ),( Inseok Kang ),( Intae Hwang ),( Cheolwoo You ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.3
In this paper, we propose a new joint precoder and postcoder design strategy to support multiple streams per user in multiuser multiple-input multiple-output (MIMO) systems. We propose two step precoding strategies using equal channel gain decomposition and block diagonalization at the transmitter. With the proposed precoder, the multiuser MIMO channel can be decomposed into multiple parallel channels with equal channel gain per user. After applying receive postcoder which is generated and sent by the transmitter, we can use ML based decoder per stream to achieve full receive diversity. Achievable sum rate bound and diversity performance of the proposed algorithm are presented with feedback signaling design and quantitative complexity analysis. Simulation results show that the proposed algorithm asymptotically approaches to the sum rate capacity of the MIMO broadcast channel while maintaining full diversity order.
김인태(Intae Kim),황성운(Seong Oun Hwang) 대한전자공학회 2018 전자공학회논문지 Vol.55 No.8
인터넷을 통해 다양한 작업이 가능해 짐으로써, 공개되어서는 안 되는 민감한 정보가 실시간으로 네트워크를 통해 대량으로 전송되고 있다. 하지만 기존의 암호 기법은 이러한 환경에 적합하지 않다. 민감한 정보가 실시간으로 네트워크를 통해 대량으로 전송되는 과정에서 암·복호화에 관련된 속성 정보 (수신자 및 송신자 정보, 소속 등)가 필요 이상으로 노출되어 공격자가 이러한 속성 정보로부터 암호화된 데이터에 대한 정보를 간접적으로 유추 해석할 수 있는 문제점을 내포하고 있다. 따라서 이런 환경에서는 전체적으로 높은 보안을 제공하기 위해 복호화를 통해 얻을 수 있는 정보가 메시지로 한정되어야할 필요가 있다. 그리고 매우 많은 사용자들을 관리함으로써 KGC에 걸리는 부하를 줄이기 위해, 계층적으로 하위 KGC를 여러 대 두어 부하를 분산시키는 현실적인 구조를 암호에도 적용시켜, KGC의 부하를 분산시키고 계층별로 효율적으로 키를 관리할 수 있는 효율적인 기법이 필요하다. 이러한 현재의 인터넷 환경에서 요구되는 요구 사항을 충족하기 위해, 본 논문에서는 표준 모델에서 안전한 선택적으로 속성을 숨기는 내적 술어에 대한 효율적인 계층적 술어 암호 기법를 제안한다. By enabling various tasks through the Internet, sensitive information that should not be disclosed is being transmitted in real time over a network. However, existing cryptography is not suitable for this environment. In the process of mass transmission of sensitive information through the network in real time, attribute information (recipient and sender information, affiliation, etc.) related to encryption/decryption is exposed more than necessary and an attacker can indirectly interpret the information about the encrypted data from the attribute information. Therefore, in this environment, in order to provide high security as a whole, information that can be obtained through decryption needs to be limited to messages. In order to reduce the load on the KGC which manages very many users, it is needed the efficient scheme to distribute the load of the KGC by applying a realistic structure that divides the load by arranging a plurality of subordinate KGC hierarchically. In order to meet the requirements of the current Internet environment, this paper proposes an efficient hierarchical predicate encryption scheme for inner product that is secure selectively attribute-hiding in the standard model.