• 한국통신학회논문지
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• 제37C권11호
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• pp.1036-1044
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• 2012

IT기술의 발전에 힘입어 지능형 센서 및 지능형 액추에이터 채택이 증가하면서 차량내 통신 네트워크를 통한 데이터 전송은 꾸준한 증가 추세를 보이고 있다. 2015년에는 차량내 통신 네트워크를 통한 전송 데이터량이 2010년 대비 2배 이상 증가하며, 차량제어에 필요한 네트워크 노드 수는 2010년 대비 1.5배 이상 증가할 것으로 전망된다. 이와 같이 차량내 데이터량의 증가가 예상됨에 따라 최근 자동차 산업계에서는 차량용 통신 네트워크로서 EtherCAT, TTEthernet 등 산업용 Ethernet에 대한 관심이 증대되고 있다. 본 논문에서는 차량내 데이터 전송을 위한 산업용 Ethernet으로 주목받고 있는 EtherCAT의 전송지연 특성과 고장복구 특성을 분석할 수 있는 모델을 제안한다. 실험용 EtherCAT 네트워크를 구성하여 제안한 모델의 정확성을 검증하였다.

• 한국정보과학회논문지:정보통신
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• 제30권3호
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• pp.343-354
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• 2003

본 논문에서는 멀티캐스트 환경에서 핸드오프 시 발생하는 패킷손실의 회복 지연시간을 최소화하는 알고리즘을 제안하였다. 제안한 알고리즘은 선행 연구인 PMTP(Predictable Multicast Protocol)와 FN(Foreign Network)간의 연계를 통해 신뢰성을 보장하며, 이동한 외부네트워크의 FA(Foreign Agent) 의 상태에 따라 터널링과 멀티캐스트 그룹 재 가입을 사용하여 양방향(hi-directional tunneling)과 원격가입(remote subscription)을 독립적으로 사용하는 경우에 발생되는 라우팅의 비효율성과 핸드오프 지연을 해결하였다. 한편, 핸드오프 지연에 의해 발생되는 패킷손실을 핸드오프 시 등록정보와 손실된 패킷 정보를 함께 전송하여 이전 FA나 현재 FA가 핸드오프 수행과 동시에 핸드오프 지연동안의 패킷손실을 최소한의 시간에 회복할 수 있도록 한다. 성능분석 결과, 제안하는 방식은 기존의 핸드오프 절차에 추가 변경 없이 사용 가능하며 양방향 방식과 원격가입 방식보다 핸드오프와 에러회복 시간에 있어 높은 성능을 보이는 것을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.90.2-90
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• 2002

A new integral controller is proposed for time-delay plants. The proposed controller has Davison type structure and utilizes a simplified state predictor instead of the optimal state predictor for the extended system. The simplified predictor is introduced by a trick similar to that used in the Smith predictor. As a systematic method for designing the proposed controller, the application of the loop transfer recovery (LTR) technique is considered. For the plant input side and the output side, explicit representations of the sensitivity matrices achieved by enforcing the formal LTR procedure using Riccati equations are obtained. A numerical example is presented to compare the asymptotic...

• 한국통신학회논문지
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• 제30권9C호
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• pp.877-886
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• 2005

Various frame recovery algorithms have been suggested to overcome the communication quality degradation problem due to Internet-typical impairments on Voice over IP(VoIP) communications. In this paper, we propose a new receiver-based recovery method which is able to enhance recovered speech quality with almost free computational cost and without an additional increment of delay and bandwidth consumption. Most conventional recovery algorithms try to recover the lost or erroneous speech frames by reconstructing missing coefficients or speech signal during speech decoding process. Thus they eventually need to modify the decoder software. The proposed frame recovery algorithm tries to reconstruct the missing frame itself, and does not require the computational burden of modifying the decoder. In the proposed scheme, the Vector Quantization(VQ) codebook indices of the erased frame are directly estimated by referring the pre-computed VQ Codebook Index Interpolation Tables(VCIIT) using the VQ indices from the adjacent(previous and next) frames. We applied the proposed scheme to the ITU-T G.723.1 speech coder and found that it improved reconstructed speech quality and outperforms conventional G.723.1 loss recovery algorithm. Moreover, the suggested simple scheme can be easily applicable to practical VoIP systems because it requires a very small amount of additional computational cost and memory space.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2013년도 추계학술발표대회
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• pp.400-401
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• 2013

Mobility in a network causes link disconnections and link recovery is vital for reliability of a network. A link failure affects all the preceding nodes on a damaged routing path; creates communication delay, throughput degradation, and congestion. This paper proposes link recovery mechanisms in CCN based networks. Packet overhearing is used to update neighboring nodes information. The recovery is done by forwarding node resulting in low control overhead, and better efficiency. The proposed mechanisms increase overall performance of a typical CCN and simulation results show that our proposed scheme works very well in densely populated networks with high mobility.

• 대한의용생체공학회:의공학회지
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• 제38권5호
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• pp.232-236
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• 2017

In this study, We investigated the effect of foot cooling on the reduction of body temperature after hard exercise at the high temperature of $40^{\circ}C$. We performed a total of 30 subjects, and the subjects performed treadmill exercise for 30 minutes. We produced the cooling device to cool the foot using Peltier module. After the end of the exercise, We performed normal recovery method and cooling recovery method(one foot, both feet) for 1 hour on the same indoor environmental conditions and confirmed the change of body temperature of subjects. The results of deep body temperature measurement showed average $38.78{\pm}0.22^{\circ}C$ to $38.54{\pm}0.15^{\circ}C$ when the normal recovery method was performed. Cooling recovery method on one foot showed average $38.69{\pm}0.14^{\circ}C$ to average $38.06{\pm}0.17^{\circ}C$ and Cooling recovery method on both feet showed average $38.69{\pm}0.15^{\circ}C$ to average $37.84{\pm}0.21^{\circ}C$. There was a significant difference between the normal recovery method and the one foot cooling recovery method(p < .05), there was a significant difference between the normal recovery method and the both feet cooling recovery method(p < .05) and there was a significant difference between the one foot cooling recovery method and the both feet cooling recovery method(p < .05). Body temperature showed the lowest decrease rate when the normal recovery method was performed, and body temperature showed the highest decrease rate when the both feet cooling recovery method was performed. Therefore, recovery of cooling on the foot after hard exercise have decreased body temperature, delay fatigue in the body, and will be contributed to improvement of athlete performance.

• 감성과학
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• 제11권4호
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• pp.637-644
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• 2008

감성을 인식하고 반응하는 감성컴퓨터를 개발하기 위한 감성인식에 대한 연구가 활발하다. 본 연구는 2차원으로 정의한 감성을 측정하기 위해서 시간에 따른 생리신호의 반응 변수를 정의하고 그 변수로 인한 감성을 구분하고자 하였다. 10명의 대학생에게 16장의 감성을 유발시킬 수 있는 이미지를 제시하였다. 그리고 자율신경계 반응으로 ECG(electrocardiogram), PPG(photoplethysmogram), GSR(Galvanic skin response), RSP (respiration), 그리고 SKT(skin temperature)를 측정하였다. 본 연구는 자율신경계 반응에 대해 Delay, Activation, Half recovery 그리고 Full recovery로 이루어진 TDP(Time Dependent Parameters)를 정의하고 감성을 구분할 수 있는지에 대한 통계적 유의성을 검증하였다. 그 결과, TDP가 감성을 구분할 수 있는 유의미한 변수로 확인하였고 특징적 경향을 보임을 알 수 있었다. 그러므로 본 연구는 TDP가 감성 인식을 위한 유효한 변수일 가능성을 보였다.

• 한국멀티미디어학회논문지
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• 제8권6호
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• pp.798-806
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• 2005

In this paper, we suggest a game system that can support network modules for multi-platform based video games, and built a system that can convert from a single-user game to multi-user game. In this system, we bring in an initial delay buffering scheme on clients to handle any periods of latency occurring from the load fluctuation in a network, when a real-time game is played, and shows that stable play for a game is achieved as the result of the scheme. This paper also presents a retransmission algorithm based on the history of game commands to handle drawbacks of UDP mechanism. And, we evaluate the network delay and packet loss using the simulation tool NS2, and shows the case of 0.3 second buffer delay is the most suitable for recovery.

• 한국통신학회논문지
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• 제33권11B호
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• pp.989-997
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• 2008

The reverse acknowledgment (RA) scheme supports a fast loss recovery for negative acknowledgment (NAK)-based selective repeat automatic repeat request (SR-ARQ) by detecting a retransmission failure quickly before a retransmission timer expires. In this paper, we evaluate the performance of a NAK-based SR-ARQ protocol with the RA scheme and compare it with the conventional NAK-based SR-ARQ protocol. Particularly, we propose a simple analysis model for the transport delay of the NAK-based SR-ARQ protocol considering the traffic condition, the retransmission persistence, the timer-based retransmissions and the RA scheme's behavior. Both NAK-based SR-ARQ protocols with and without the RA scheme are implemented by using the OPNET simulator. We verified the analysis model's accuracy through the simulation results. Also, we evaluate the performance of the NAK-based SR-ARQ protocol with the RA scheme based on analysis and simulation results.

• The Korean Journal of Pain
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• 제22권2호
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• pp.176-180
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• 2009

Cases of pyogenic spondylodiscitis are relatively rare diseases that concern 2-7% of total cases of osteomyelitis. Owing to the low frequency and initial nonspecific nature of signs and symptoms, diagnosis is often delayed up to 2-6 months. If the proper treatment is not established due to a diagnostic delay, there is a possibility of a serious neurologic deficit and spinal instability. We report two cases of infectious spondylodiscitis which were misdiagnosed as compression fracture and spinal stenosis respectively. They could be correctly diagnosed after MRI and laboratory test and under the recovery state after an antifungal and antibiotic medication. Special careful attention during the diagnostic procedure is a really important step considering the diagnostic delay and its resultant unsatisfactory outcome.