Generic Iterative Downlink Interference Alignment

SHIN, Won-Yong,YOON, Jangho 'Institute of Electronics, Information and Communi 2015 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb98 No.5

Energy-Efficient Opportunistic Interference Alignment With MMSE Receiver

Shin, Won-Yong,Yoon, Jangho The Institute of Electronics and Information Engin 2014 IEIE Transactions on Smart Processing & Computing Vol.3 No.2

This paper introduces a refined opportunistic interference alignment (OIA) technique that uses minimum mean square error (MMSE) detection at the receivers in multiple-input multiple-output multi-cell uplink networks. In the OIA scheme under consideration, each user performs the optimal transmit beamforming and power control to minimize the level of interference generated to the other-cell base stations, as in the conventional energy-efficient OIA. The result showed that owing to the enhanced receiver structure, the OIA scheme shows much higher sum-rates than those of the conventional OIA with zero-forcing detection for all signal-to-noise ratio regions.

Energy-Efficient Opportunistic Interference Alignment

Jangho Yoon,Won-Yong Shin,Hwang Soo Lee IEEE 2014 IEEE communications letters Vol.18 No.1

<P>We introduce an energy-efficient distributed opportunistic interference alignment (OIA) scheme that greatly improves the sum-rates in multiple-cell uplink networks while reducing the transmit power consumption compared to the conventional OIA scheme. In the proposed scheme, each user employs optimal transmit vector design and power control strategy in the sense of minimizing the amount of generated interference to other-cell base stations while satisfying a given required signal quality. Our main result indicates that owing to the reduced interference level, the proposed OIA method attains larger sum-rates than those of OIA with no power control (i.e., with full transmit power) for almost all signal-to-noise ratio regions, thus resulting in improved energy efficiency.</P>

시간지연제어기법을 이용한 헥사콥터 고장허용 제어

이장호(Jangho Lee),신동호(Dongho Shin),정진덕(Jindeog Chung) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-

Multi-rotor unmanned aerial vehicles (UAV) have been adopted in many areas in recent years. If one or multiple actuators failure occurs during flight, the UAV may not be able to maintain a controlled flight or even worse, it could be crashed due to lose of control authority. Likewise, if a conventional quadrotor is subjected to a failure of a rotor, it may exhibit unacceptable performance even if fault tolerant control (FTC) method is adopted. In order to overcome the drawback of the quadrotor, the hexacopter, which has six rotors instead of four, has been developed to increase reliability and controllability even at the mechanical fault conditions such as degradation of motor performance or even worse electric motor failure. A novel attitude tacking control method using Time Delay Control (TDC) scheme is developed to provide robust controllability of a rigid hexacopter in case of single or multiple rotor faults. When the TDC scheme is developed, the rotor faults such as the abrupt and/or incipient rotor faults are considered as model uncertainties. The kinematics, modeling of rigid dynamics of hexacopter, and design of stability and controllability (SCAS) are addressed rigorously in this paper. In order to compare the developed control scheme to a conventional control method, a nonlinear numerical simulation was performed and the attitude tracking performance was compared between the two methods considering the single and multiple rotor faults cases. The developed control scheme shows superior stability and robust controllability of a hexacopter that is subjected to one or multiple rotor faults and external disturbance, i.e., wind shear, gust, and turbulence.

환경모니터링을 위한 집비둘기 알 껍데기의 중금속 축적특성 연구

이장호 ( Jangho Lee ),이종천 ( Jongchun Lee ),박종혁 ( Jong Hyouk Park ),이유진 ( Eugene Lee ),심규영 ( Kyuyoung Shim ),김명진 ( Myungjin Kim ),신영규 ( Youngkyu Shin ) 한국환경영향평가학회 2015 환경영향평가 Vol.24 No.6

The heavy metal accumulations of avian eggshells were studied in order to test a feral pigeon (Columba livia)`s eggshell as an indicator for the environmental monitoring of pollutants. The reviews on the eggs of the different 19 avian species showed that it is the eggshell rather than the egg content that can better reflect the heavy metals in the environment; in most cases the CVs (coefficients of variations) of the heavy metal concentrations in the eggshells were higher than those in the egg contents. This can indicate that the heavy metal accumulations are homeostatically controlled in the egg contents, but the accumulations in the eggshells are varied according to the environmental conditions. To test the reviews, the feral pigeon eggs from the two different sites, one representing urban and the other rural environment, were analyzed for lead (Pb) and cadmium (Cd). The result showed that the eggshells of the urban pigeons (Hangang) had the higher metal concentrations than those of the rural pigeons (Hampyeong). The same difference can also be found in the internal organs (liver, bone) and blood. However, the analyses of the egg contents between the two sites did not reveal the differences. In other words, the result suggests that the feral pigeons, like the other avian species, are able to control the heavy metals into the egg contents homeostatically. Therefore, it is more useful to use the feral pigeon eggshell rather than the egg content in case of monitoring heavy metals in different habitats.

Time Delay Fault Tolerant Controller for Actuator Failures during Aircraft Autolanding

LEE, Jangho,CHOI, Hyoung Sik,LEE, Sangjong,KIM, Eung Tai,SHIN, Dongho THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIEN 2012 Transactions of the Japan Society for Aeronautical Vol.55 No.3

<P>A time delay control methodology is adopted to cope with degraded control performance due to control surface damage of unmanned aerial vehicles, especially in the case of the automatic landing phase. It is a crucial challenge to maintain consistent control performance even under fault environments such as stuck and/or incipient actuator faults. Flight control systems designed using conventional feedback control methods in such cases may result in unsatisfactory performance, and even worse, may not guarantee the closed-loop stability, which is fatal for aircraft in the state of auto-landing. To overcome the shortfalls of the conventional approach, the time delay control scheme is adopted. This scheme is known to be robust against disturbance, model uncertainties and so on. Motivated by the fact that the abrupt and/or incipient actuator faults focused on in this paper could be considered as model uncertainties, we consider the application of the time delay controller to designing a fault tolerant control system. To show the effectiveness of the time delay control method, a nonlinear 6-DOF simulation is performed under model uncertainties and wind disturbances, and control performance is compared with that of conventional controllers in the case of multiple and single actuator faults.</P>

Lyapunov Control Law for Automatic Approach for Unmanned Helicopter Landing

LEE, Jangho,KIM, Seong Pil,SHIN, Dongho,CHOI, Hyoung Sik,SEONG, Kie Jeong,KIM, Youdan THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIEN 2011 Transactions of the Japan Society for Aeronautical Vol.53 No.182

<P>Describing the flight behavior of a helicopter is a difficult challenge in mathematical modeling. A rotorcraft can be considered as a complex arrangement of interacting subsystems, and the problem is dominated by rotor. The rotor blades bend and twist under the influence of unsteady and nonlinear aerodynamic loads, which are themselves a function of blade motion. This problem makes it more difficult to estimate the behavior of a helicopter. Furthermore, it is difficult to design a flight controller for unmanned helicopter systems. In this paper, to obtain a nonlinear dynamic model of a helicopter, parameter identification is performed using flight test data. A globally stable tracking control law for agile and precise landing of an unmanned helicopter is proposed. A near-minimum time control scheme is adopted to design the reference trajectory, and it is shown that the control law is guaranteed to be stable globally in the sense of Lyapunov. A flight test verified the performance of the proposed method. Performance can be improved by choosing the control parameters via optimization. The proposed method can be extended to a multiple output trajectory tracking problem for a precise fixed-wing UAV landing.</P>

Does Concurrent Introduction of Small Cost-sharing and Gatekeeping Arrangements Reduce Health Care Spending? Evidence from Medical Aid Reform in South Korea

Yoon Jangho,Shin Hyun-woong,Noh Yun-hong,Yeo Nageum 한국보건사회연구원 2015 保健社會硏究 Vol.35 No.4

본 연구는 2007년 수행된 「의료급여혁신 종합대책」이 의료급여 급여비 지출감소에 영향을 미쳤는지를 실증적으로 분석해봄으로써 본인부담금제, 선택병의원제도입과 같은 수급권자 측면의 제도개선이 의료비 지출 감소에 미치는 효과를 확인해보고자 하였다. 이를 위해 국민건강보험공단의 의료급여통계연보를 사용하여 16개시도 지역의 2003년 1/4분기부터 2010년 4/4분기까지 총 32분기 자료로 횡단면 자료와 시계열자료가 결합된 페널 데이터를 구축하였다. 그리고 「의료급여혁신 종합대책」이 실행된 2007년 3분기 시점을 제도변화 변수로 놓고, DID 분석을 통해 의료급여 수급자당 외래, 입원, 약국 진료비의 변화를 분석하였다. 분석 결과 「의료급여혁신 종합대책」도입 후, 도입 이전보다 분기 당 평균 15.6%의 의료비 지출이 감소하였으며, 이러한 의료비 지출 감소가 대부분 도입된 제도와 직접 관련 있는 외래 진료비 감소에 기인한 것을 확인하였다. 반면, 입원과 약국 진료비 지출 감소는 유의하지 않았다. 한편, 이러한 수요자 측면에서 의료이용을 제한하는 정책은 의료비 지출 감소에는 효과가 있지만, 의료수급권자의 의료 보장수준을 저해할 수 있는 만큼 향후, 의료급여 급여비지출 뿐만 아니라 의료 접근성 및 건강결과에 미치는 영향까지 포함한 제도효과 분석연구가 추가적으로 수행되어야 할 필요가 있겠다. On July 1, 2007, South Korea`s Medical Aid program for financially needy families introduced a major reform to dampen spending growth. The reform was comprised of two elements, which were simultaneously implemented: small patient copayments for outpatient services, and a financial incentive for patients to designate a primary health care provider (a gatekeeping arrangement). We test whether this reform led to reductions in health spending. Using 32-quarter region-level panel data for the entire South Korean Medical Aid beneficiaries from 2003 to 2010, we calculate difference-in-differences estimates of per-enrollee health care costs separately for outpatient visit, hospitalization and medication. We also test mechanisms through which the reform could influence health care spending. We find that the Medical Aid reform led to approximately 15.6% reductions in spending per quarter during the 3 1/2-year follow-up period, primarily due to a reduction in outpatient visits. There is no evidence that the reform led to reductions in hospitalization and medication costs. We conclude that even a small copayment, in combination with a gatekeeping arrangement, could lead to substantial reductions in outpatient spending in a government-funded health care assistance program.

Elastic Routing in Ad Hoc Networks with Directional Antennas

Yoon, Jangho,Shin, Won-Yong,Jeon, Sang-Woon IEEE 2017 IEEE transactions on mobile computing Vol.16 No.12

<P>Throughput scaling laws of an ad hoc network equipping directional antennas at each node are analyzed. More specifically, this paper considers a general framework in which the beam width of each node can scale at an arbitrary rate relative to the number of nodes. We introduce an elastic routing protocol, which enables to increase per-hop distance elastically according to the beam width, while maintaining an average signal-to-interference-and-noise ratio at each receiver as a constant. We then identify fundamental operating regimes characterized according to the beam width scaling and analyze throughput scaling laws for each of the regimes. The elastic routing is shown to achieve a much better throughput scaling law than that of the conventional nearest-neighbor multihop for all operating regimes. The gain comes from the fact that more source-destination pairs can be simultaneously activated as the beam width becomes narrower, which eventually leads to a linear throughput scaling law. In addition, our framework is applied to a hybrid network consisting of both wireless ad hoc nodes and infrastructure nodes. As a result, in the hybrid network, we analyze a further improved throughput scaling law and identify the operating regime where the use of directional antennas is beneficial. In addition, we perform numerical evaluation in both ad hoc and hybrid networks, which completely validates our analytical results.</P>

Ceiling Work Scenario Based Hardware Design and Control Algorithm of Supernumerary Robotic Limbs

Chang-Yeob Shin,Jangho Bae,Daehie Hong 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10