Understanding Korean Webtoon Culture: Transmedia Storytelling, Digital Platforms, and Genres by Dal Yong Jin / Review

Hojin Song 서울대학교 규장각한국학연구원 2023 Seoul journal of Korean studies Vol.36 No.2

Multicast Transmission for Asynchronous Data Requests

Song, Hojin,Choi, Wan IEEE 2018 IEEE Transactions on Vehicular Technology VT Vol.67 No.4

<P>This paper considers a two-user asynchronous multicast scenario where both users request the same content at different time instances, and a base station simultaneously serves them with nonorthogonal transmission. To serve the asynchronous requests of the same content, we develop three nonorthogonal transmission schemes. The first scheme serves the asynchronous requests by unicast transmission and the second scheme enables multicast transmission for the asynchronous requests based on interference decoding capability at receiver. The third scheme combines the first and second schemes. For the three proposed schemes, we formulate completion time minimization problems that aim to minimize the time required to complete serving users, while ensuring a given quality constraint of streaming content. For each scheme, the feasibility condition in terms of transmit power and optimal rate control are investigated. In addition, we analytically compare the performance of the proposed schemes, and additionally, propose an opportunistic transmission that opportunistically switches three proposed schemes depending on the channel and power conditions.</P>

Optimal Content Placement for Wireless Femto-Caching Network

Song, Jaeyoung,Song, Hojin,Choi, Wan IEEE 2017 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.16 No.7

<P>This paper investigates optimal content placement for wireless femto-caching network. The average bit error rate (BER) is formulated as a function of content placement under wireless fading. To minimize the average BER, we propose a greedy algorithm finding optimal content placement with low-computational complexity. Exploiting the property of the optimal content placement which we derive, the proposed algorithm can be performed over considerably reduced search space. Contrary to the optimal content placement without consideration of wireless fading aspects, we reveal that optimal content placement can be reached by balancing a tradeoff between two different gains: file diversity gain and channel diversity gain. Moreover, we also identify the conditions that the optimal placement can be found without running the proposed greedy algorithm and derive the corresponding optimal content placement in closed form.</P>

On the Optimal Switching Probability for a Hybrid Cognitive Radio System

Hojin Song,Jun-Pyo Hong,Wan Choi IEEE 2013 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.12 No.4

<P>Cognitive radio (CR) systems are typically classified into two types. In overlay CR, a secondary user opportunistically accesses primary user's spectrum when it is unused, while a secondary user in underlay CR accesses the spectrum at any time as long as the interference power received at a primary user is below a certain level. This paper investigates a hybrid CR system where a secondary user probabilistically changes its spectrum access mode for secondary user's throughput maximization while guaranteeing primary user's target throughput. Basically, the hybrid CR works like overlay CR. The secondary user constantly monitors activity of the primary user and transmits data with maximum transmit power if transmission of the primary user is not detected. However, the only difference from overlay CR is that even when transmission of the primary user is detected, the secondary users are able to access the spectrum with regulated low transmit power with switching rate c. We show that there is a trade-off of increasing c due to recursive interactions between primary and secondary users, and optimizing c is crucial to balance the gain and loss of secondary user's underlay spectrum access. The proposed hybrid CR is shown to achieve higher throughput and be more robust to detection errors than conventional CR systems.</P>

Joint Power and Rate Control for Device-to-Device Communications in Cellular Systems

Hojin Song,Jong Yeol Ryu,Wan Choi,Schober, Robert IEEE 2015 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.14 No.10

<P>This paper investigates device-to-device (D2D) communication nested in a cellular network, where a pair of D2D users directly exchanges their information using the uplink frequency band of the cellular network. When the D2D user treats the interference from the cellular user as noise, power control at the cellular user is optimal for maximizing the rate of the cellular user while controlling the interference to the D2D user. However, if the D2D user can perform successive interference cancelation (SIC), the cellular user needs to adjust both transmit power and rate to maximize its rate, because the decodability of the interfering signals at the D2D user depends not only on the signal power but also on the rate of the cellular user. To control the interference from the cellular user, we propose a joint transmit power and rate control scheme at the cellular user. Forcing the cellular user to transmit with a reduced data rate compared with the maximum possible rate, given its transmit power, the proposed joint power and rate control scheme efficiently enables SIC at the D2D user. To reduce the computational complexity, we also propose a near-optimal scheme that employs either power control or rate control depending on the channel conditions.</P>

Characterization of the Pareto Boundary for the Two-User Symmetric Gaussian InterferenceChannel

Hojin Song,Jong Yeol Ryu,Wan Choi IEEE 2014 IEEE TRANSACTIONS ON COMMUNICATIONS Vol.62 No.8

<P>We characterize the Pareto boundary of the achievable rate region of the two-user symmetric Gaussian interference channel when transmitters control their transmission power and receivers have successive interference cancellation capability. By identifying the shape of achievable rate region according to the strength of interference channels, we find combinations of decoding and power allocation strategies achieving the Pareto boundary. We also characterize the Pareto boundary of the achievable rate region when time sharing is additionally considered.</P>

국방 컴포넌트 구조 및 플랫폼 구축을 위한 도메인 분석

송호진(Hojin Song),최은만(Eun Man Choi),김영철(Young-chul Kim),전병국(Byung Kook Jeon),박철민(Chulmin Park),조병인(Byung In Cho) 한국정보과학회 2002 한국정보과학회 학술발표논문집 Vol.29 No.2Ⅱ

지금까지의 국방 응용업무는 적용분야 및 개발환경에 깊이 의존된 연통형 개발방법으로 구축되어 타 응용 체계와의 상호운용성이 매우 부족한 상태이다. 또한 유사한 체계를 개발할 때 이미 개발된 동일 기능의 프로그램이 있는 경우라 하더라도 재사용성이 미흡하여 새롭게 중복 개발되곤 했다. 재사용의 가능성을 높이고 상호운용성을 충분히 확보하기 위하여 컴포넌트 기반의 소프트웨어 구축이 필요하다. 이 논문에서는 국방 컴포넌트 구조를 확립하기 위한 기초 연구로 도메인 분석을 수행하였다. 특히 군수 분야의 업무 흐름을 파악하여 컴포넌트화 가능한 기능들을 찾아내었다. 기능 중심의 도메인 분석 방법을 적용하여 컴포넌트가 된 부분을 찾아내었고 이들은 향후 국방 소프트웨어 구조의 일부로 정의될 것이다.

컴포넌트 테스트를 위한 래퍼의 자동 생성에 관한 연구

송호진(Hojin Song),최은만(Eun Man Choi) 한국정보과학회 2005 정보과학회논문지 : 소프트웨어 및 응용 Vol.32 No.8

미리 만들어진 컴포넌트를 조립하여 새로운 소프트웨어를 개발하는 방법은 개발비용과 기간을 획기적으로 줄일 수 있다는 장점으로 전통적인 방법의 대안이 되고 있다. 하지만 컴포넌트를 통합 조립하면서 신뢰도를 확인하고 새 환경에 맞는지 테스트하는 과정이 복잡하고 비용이 많이 소요된다면 효과적인 방법이 될 수 없다. 대규모 시스템에 효율적으로 사용, 조립될 컴포넌트들은 원시코드 형태로 배포되지 않아서 새 환경에 적합한지 시험하고 관찰하는 철저한 테스트가 어렵다. 이러한 문제점을 해결하기 위하여 컴포넌트가 재사용되었을 때 쉽게 검증되도록 미리 테스트 모듈을 내장한 Built-In 테스트 방법이 있지만 컴포넌트의 기능이 다양하고 복잡하게 되면 컴포넌트에 포함된 테스트 모듈의 규모가 커지고 다양하고 융통성 있는 테스트가 어려워진다. 이 논문에서는 컴포넌트의 Built-In 테스트 기능을 대체할만한 컴포넌트 테스트를 위한 래퍼(wrapper)를 제안하고 이를 설계, 구현하여 실용성을 보였다. 래퍼를 자동 생성하여 테스트하면 컴포넌트의 테스트 준비 과정에 드는 노력이 줄어들고 테스트를 다양한 측면에서 테스트해 볼 수 있다. Assembling new software systems from prepared components is an attractive alternative to traditional software development method to reduce development cost and schedule dramatically. However, if separately developed components are tested, integrated and verified with unreasonable effort and high cost, it would not be an effective way to software development. Components are not distributed in the shape of white-box source code so that should be hard to validate and test in new application environment. For solving this problem, built-in tester components are suggested to check the contract-compliance of their server components. If components have various and complex function, built-in tester should be heavy and unflexible to test in composition of components. This paper suggests enhancing automated wrapper technique which substitutes with built-in tester components and shows the usability of the wrapper by design and implementation. Component testing in this way reduces the cost and effort associated with preparation of component testing and makes the various test experiments in components assembly.

바이오차를 이용한 지하수내 중금속 처리

송호진 ( Hojin Song ),최지혜 ( Jihye Choi ),조윤철 ( Yunchul Cho ) 한국물환경학회(구 한국수질보전학회) 2019 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2019 No.-

펨토 캐싱 시스템의 최적 콘텐츠 저장 기법 에 관한 연구

송재영(Jaeyoung Song),송호진(Hojin Song),최완(Wan Choi) 한국통신학회 2016 한국통신학회 학술대회논문집 Vol.2016 No.6