• 한국통신학회논문지
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• 제38A권8호
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• pp.662-668
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• 2013

무선이동통신 시스템은 무선 채널상황에 맞게 변조 파라미터와 부호율 등을 적응적으로 변화시켜 성능 이득을 얻을 수 있는 다양한 전송기법을 채택해오고 있다. 그 중에서 재전송 기법과 오류정정부호의 패리티 양을 적응적으로 조절하여 전송하는 incremental redundancy hybrid ARQ (IR-HARQ) 방식은 시스템 수율 측면에서 효율적인 것으로 알려져 있으며 다양한 무선이동통신시스템에서 사용되고 있다. 본 논문에서는 이중 대각 패리티 구조를 갖는 블록 LDPC의 IR-HARQ 방식을 제안한다. IR-HARQ 설계 시 모부호에 의해 부호화된 비트의 전송 순서가 성능을 좌우하는 것을 고려하여 전송 우선순위를 정의하고 전송 패킷 구성 규칙을 제안한다. 제안한 방식의 성능 분석을 다양한 변조 파라미터 및 부호율에서 수행하였으며, 다중 안테나 모드에 따른 시스템 수율 성능을 제시한다. 성능 분석 결과를 통해 제안한 방식은 기존의 방식에 비해 성능 이득을 얻음을 확인할 수 있다.

• Asia Marketing Journal
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• 제9권2호
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• pp.97-129
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• 2007

오프라인 소매점의 상권은 점포를 방문하는 소비자의 지역분포에 의해 결정된다. 그리고 점포에서 매출의 발생과 실현이 동시에 이루어진다. 물적이동이 요구되는 상품을 판매하는 온라인 소매점의 상권은 물류 배송망을 통하여 소비자가 지정하는 시간/장소에 소비자/ 판매자가 부담할 수 있는 배송비 미만으로 배달할 수 있는 공간/지역범위에 의해 결정된다. 온라인매출은 배달완료로서 실현되기 때문이다. 온라인 쇼핑몰의 상권은 택배망의 효율성과 신뢰성에 의하여 결정된다고 할 수 있다. 우리나라에는 온라인 매출이 연간 36%나 고성장함에도 불구하고 매출실현이 이루어지는 지역별 매출/배송밀도에 관한 온라인 상권지도조차 없었다. 그러므로 36%씩의 수요증가에 대한 배송능력/배송망도 단기적/중장기적 대응책이 어떻게 추진되는가에 대한 연구도 없었다. 본 연구에서는 (1) 국내최초로 온라인 상권지도를 제시하였다. (2) 배송수요의 고속 증가에 대한 택배업계의 단기적/중장기적 대응책을 실증조사 하였다. (3) 연구결과는 세가지로 요약되었다. 첫째, 화장품과 같은 편의품의 경우에도 온라인 상권은 전국으로 광역화되고 있음을 파악하였다. 온라인 쇼핑의 매출성장을 주도하는 인기상품(hot selling items)도 저가격의 의류, 표준품으로서 오프라인 상권에서는 상품의 이동범위(range of goods)가 적은 상품이었으나 전국상권으로 광역화되는 현상을 1년간의 매출분포 지도를 통하여 제시하였다. 둘째, 온라인 매출증가에 따라 배송물량의 증가 배송가격인하 → 배송원가인하 → 서비스품질 향상의 현상이 나타나고 있었다. 셋째, 수요증가에 대한 택배업계의 단기적 대응은 지역별로 이루어지고 있으나 간선물류망 (허브, 간선운송)에 대한 중장기 대책이 감지되지 못하였다. (4) 본 연구 및 실증조사의 한계와 이를 바탕으로 한 미래 연구 방향을 제시하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.757-770
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• 2020

We propose a hand gesture recognition method that is compatible with a head-up display (HUD) including small processing resource. For fast link adaptation with HUD, it is necessary to rapidly process gesture recognition and send the minimum amount of driver hand gesture data from the wearable device. Therefore, we use a method that recognizes each hand gesture with an inertial measurement unit (IMU) sensor based on revised correlation matching. The method of gesture recognition is executed by calculating the correlation between every axis of the acquired data set. By classifying pre-defined gesture values and actions, the proposed method enables rapid recognition. Furthermore, we evaluate the performance of the algorithm, which can be implanted within wearable bands, requiring a minimal process load. The experimental results evaluated the feasibility and effectiveness of our decomposed correlation matching method. Furthermore, we tested the proposed algorithm to confirm the effectiveness of the system using pre-defined gestures of specific motions with a wearable platform device. The experimental results validated the feasibility and effectiveness of the proposed hand gesture recognition system. Despite being based on a very simple concept, the proposed algorithm showed good performance in recognition accuracy.

• 환경생물
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• 제35권1호
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• pp.37-46
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• 2017

Climate change is the biggest concern of the $21^{st}$ century. Greenhouse gas (GHG) emissions from various sectors are attracting attention as a cause of climate change. The DeNitrification-DeComposition (DNDC) model simulates GHG emissions from cropland. To study future GHG emissions using this simulation model, various factors that could change in future need to be considered. Because most problems are from the agricultural sector, DNDC would be unable to solve the factor-changing problem itself. Hence, it is necessary to link DNDC with separate models that simulate each element. Climate change is predicted to cause a variety of environmental disasters in the future, having a significant impact on the agricultural environment. In the process of human adaptation to environmental change, the distribution and management methods of farmland will also change greatly. In this study, we introduce some drawbacks of DNDC in considering future changes, and present other existing models that can rectify the same. We further propose some combinations with models and development sub-models.

• 로봇학회논문지
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• 제12권2호
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• pp.184-193
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• 2017

This work shows how to create an algorithm and implementation for motion and image matching between a vehicle simulator and Unity 3D based virtual object. The motion information of the virtual vehicle is transmitted to the real simulator via a RS232 communication protocol, and the motion is controlled based on the inverse kinematics solution of the platform adopting rotary-type six actuators driving system. Wash-out filters to implement the effective motion of the motion platform are adopted, and thereby reduce the dizziness and increase the realistic sense of motion. Furthermore, the simulator system is successfully designed aiming to reducing size and cost with adaptation of rotary-type six actuators, real driving environment via VR (Virtual Reality), and control schemes which employ a synchronization between 6 motors and 3rd order motion profiles. By providing relatively big sense of motion particularly in impact and straight motions mainly causing simulator sickness, dizziness is remarkably reduced, thereby enhancing the sense of realistic motion.

• Journal of information and communication convergence engineering
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• 제7권4호
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• pp.475-479
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• 2009

In ad hoc network, the scarce energy management of the mobile devices has become a critical issue in order to extend the network lifetime. Current research activity for the Minimum Energy Multicast (MEM) problem has been focused on devising efficient centralized greedy algorithms for static ad hoc networks. In this paper, we consider mobile ad hoc networks(MANETs) that could provide the reliable monitoring and control of a variety of environments for remote place. Mobility of MANET would require the topology change frequently compared with a static network. To improve the routing protocol in MANET, energy efficient routing protocol would be required as well as considering the mobility would be needed. In this paper, we propose a new method, the CACH(Context-aware Clustering Hierarchy) algorithm, a hybrid and clustering-based protocol that could analyze the link cost from a source node to a destination node. The proposed analysis could help in defining the optimum depth of hierarchy architecture CACH utilize. The proposed CACH could use localized condition to enable adaptation and robustness for dynamic network topology protocol and this provide that our hierarchy to be resilient. As a result, our simulation results would show that CACH could find energy efficient depth of hierarchy of a cluster.

• 대한기계학회논문집A
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• 제25권4호
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• pp.685-694
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• 2001

In this study, a transfemoral prosthesis system of which both stance phase and swing phase are controllable has been developed for the recovery of the biomechanical function of the amputated leg. It consists of a 5 bar link mechanism, a hydraulic-rubber knee damper for stance phase control and a pneumatic cylinder controlled via a microprocessor for stance phase control. The mechanical characteristics of the knee damper which absorbs the impact energy generated at the heel contact were investigated. The characteristics of the pneumatic cylinder essential for the speed adaptation of the prosthesis during swing phase were also studied for its mechanical characteristics. The prosthesis was subject to the clinical tests, and the gait characteristics obtained were very close to those of normal subjects. The stance and swing controlled prosthesis that were developed in this study showed good stability during the stance phase and showed good controllability during the swing phase.

• 한국소음진동공학회논문집
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• 제25권11호
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• pp.753-763
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• 2015

This paper proposes a decentralized robust adaptive neural network control scheme using multiple radial basis function neural networks for electrically driven robot manipulators with bounded input voltages in the presence of uncertainties. The proposed controller considers both robot link dynamics and actuator dynamics. Practically, the controller gain coefficients applied at each joint may be nonlinear time-varying and the input voltage at each joint is saturated. The proposed robot controller overcomes the various uncertainties and the input voltage saturation problem. The proposed controller does not require any robot and actuator parameters. The adaptation laws of the proposed controller are derived by using the Lyapunov stability analysis and the stability of the closed-loop control system is guaranteed. The validity and robustness of the proposed control scheme are verified through simulation results.

• Animal cells and systems
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• 제13권2호
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• pp.119-125
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• 2009

Mammalian hibernation is a type of natural adaptation that allows organisms to avoid harsh environment and to increase the possibility of survival. To investigate the molecular link between circadian and hibernating rhythms in the greater tube-nosed bats, Murina leucogaster, we set out to identify circadian genes that are expressed in bats, with specific focus on the PAS domain by using PCR-based screens. We could isolate a eDNA clone, designated as LPAS1, that encodes a protein of 521 amino acid residues. LPAS1 is closely related with CLOCK family with the highest homology to human CLOCK. Based on RT-PCR analyses, LPAS1 transcripts are ubiquitously present in tissues from both summer active and winter dormant periods. Given that LPAS1 is a member of the bHLH-PAS protein superfamily but lacks polyglutamine transactivation domains, it is likely to function as a repressor for endogenous CLOCK to hinder its roles in promoting transcription. Our result will open a new avenue to further examine the functional interconnection between the circadian clock and the circannual clock such as mammalian hibernation.

• 한국항행학회논문지
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• 제14권2호
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• pp.198-205
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• 2010

유비쿼터스 환경에서 사용자가 언제 어디서나 네트워크에 접속할 수 있도록 하기 위해 다중 인터페이스 기술에 대한 관심과 연구가 늘고 있다. 본 논문에서는 다중 인터페이스를 탑재한 이동 단말이 이동 중에 단일 인터페이스만 고정적으로 이용하지 않고, 계속해서 변화하는 무선 채널의 상태에 따라 적절한 인터페이스를 적응적으로 이용하기 위한 기법을 제안한다. 본 논문에서 제안하는 기법은 각 인터페이스의 전송률과 패킷 오류율, 그리고 종단간 지연시간에 따라 가장 적절한 무선 인터페이스를 판단할 수 있다. 시뮬레이션 결과 본 논문에서 제안한 기법이 쓰였을 때 단일 인터페이스만 사용한 환경보다 약 20% 더 많은 패킷 전송을 할 수 있었다.