• 한국정보통신학회논문지
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• 제17권7호
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• pp.1602-1608
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• 2013

PoC (Push-to-Talk over Cellular)는 이동통신망에서 SIP (Session Initiation Protocol) 기반의 VoIP (Voice over Internet Protocol) 기술을 이용하여 일-대-일 또는 일-대-다 통신을 지원하는 특징으로 인하여 재난망에서 이를 적용하기 위한 노력이 현재 시도중이다. 이러한 노력은 그룹 통신 지원이 핵심이며 이를 위한 표준화 제정이 진행중이다. 하지만, 현재 표준의 경우 재난망의 특징을 반영하지 않고 일반 PoC 서비스 중심의 그룹 통신을 지원하기 때문에 재난통신망 적용시 그룹이 특정 지역에 밀집한 경우 PoC 서버에 로드가 집중됨으로써 혼잡 및 이로 인한 지연이 길어지는 문제점이 존재한다. 이러한 문제점을 해결하기 위해서 본 논문에서는 특정 지역의 PoC 서버의 로드를 다수의 PoC 서버가 처리할 수 있도록 분산시킴으로써 강건성 및 전송 지연을 줄이기 위한 새로운 방안을 제안한다. 마지막으로 시뮬레이션을 통하여 성능 평가 결과를 제시한다.

• Journal of Communications and Networks
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• 제17권4호
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• pp.351-361
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• 2015

In this paper, a new decoding scheme is proposed to improve the error correcting performance of low-density parity-check (LDPC) codes in high signal-to-noise ratio (SNR) region by using post-processing. It behaves as follows: First, a conventional LDPC decoding is applied to received LDPC codewords one by one. Then, we count the number of word errors in a predetermined number of decoded codewords. If there is no word error, nothing needs to be done and we can move to the next group of codewords with no delay. Otherwise, we perform a proper post-processing which produces a new soft-valued codeword (this will be fully explained in the main body of this paper) and then apply the conventional LDPC decoding to it again to recover the unsuccessfully decoded codewords. For the proposed decoding scheme, we adopt a simple product code structure which contains LDPC codes and simple algebraic codes as its horizontal and vertical codes, respectively. The decoding capability of the proposed decoding scheme is defined and analyzed using the parity-check matrices of vertical codes and, especially, the combined-decodability is derived for the case of single parity-check (SPC) codes and Hamming codes used as vertical codes. It is also shown that the proposed decoding scheme achieves much better error correcting capability in high SNR region with little additional decoding complexity, compared with the conventional LDPC decoding scheme.

• 한국통신학회논문지
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• 제34권11B호
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• pp.1178-1190
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• 2009

무선 랜에서 다양한 QoS를 제공하기 위해 제안된 IEEE 802.11e는 경쟁기반의 EDCA와 비경쟁 기반인 HCCA 모드를 가진다. 802.11e의 중앙제어 방식인 HCCA는 효율적인 자원분배를 하는 스케줄링 알고리즘을 필요로 한다. 그러나 기존의 HCCA 스케줄러 알고리즘들은 VBR 트래픽 제공하는 실시간 서비스에 QoS를 보장하는데 있어 어려움이 있다. 본 논문에서는 VBR 트래픽에 대하여 QoS를 보장하는 효율적인 자원분배를 위해 평균자원 할당과 최대 자원 할당방법을 동시에 사용하는 이중 리키 버킷을 사용하였다. QoS 보장 된 스테이션의 개수를 최대화하기 위하여 statistical 접근법을 사용하여 각 스테이션의 필요한 TXOP의 최소값을 구하였다. 시뮬레이션 결과는 제안한 알고리즘의 성능이 참조 스케줄러와 비교하여 전송률과 전송 지연 측면에서 성능이 좋음을 보여준다.

• Journal of Biosystems Engineering
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• 제39권2호
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• pp.134-141
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• 2014

Purposes: This study was to validate the Robotic Smart Work System that can provides better working conditions and high productivity in unstructured environments like bio-industry, based on a tele-operation system for fruit harvesting with low cost 3-D positioning system on the laboratory level. Methods: For the Robotic Smart Work System for fruit harvesting and cultivation management in agriculture, a vision based tele-operating system and 3-D position information are key elements. This study proposed Robotic Smart Farming, an agricultural version of Robotic Smart Work System, and validated a 3-D position information system with a low cost omni camera and a laser marker system in the lab environment in order to get a vision based tele-operating system and 3-D position information. Results: The tasks like harvesting of the fixed target and cultivation management were accomplished even if there was a short time delay (30 ms ~ 100 ms). Although automatic conveyor works requiring accurate timing and positioning yield high productivity, the tele-operation with user's intuition will be more efficient in unstructured environments which require target selection and judgment. Conclusions: This system increased work efficiency and stability by considering ancillary intelligence as well as user's experience and knowhow. In addition, senior and female workers will operate the system easily because it can reduce labor and minimized user fatigue.

• 방송공학회논문지
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• 제4권2호
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• pp.164-175
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• 1999

본 논문에서는 QPSK 디지틀 전송 기술을 사용하는 위성방송 전송 시스템에 대한 위성 채널 특성과 전송 신호 특성에 대한 영향을 분석하여 전송 시스템의 설계 기준점을 결정할 수 있도록 하였다. 전송 채널 특성에 의한 열화도는 약 2.0dB, 전송 신호 스펙트럼 특성에 의한 열화는 0.4dB, 그리고 수신기 특성에 대해 약 0.2dB의 열화 특성을 갖는 위성 및 전송 시스템에 대한 가용 설계 파라미터 값들을 제안하였다. 열화 특성을 만족하는 설계 파라미터 값들은 ${\pm}\;0.5dB$ 이내의 진폭 응답 특성 그리고 0.1nsec/MHz, $0.2sec/MHz^2$ 이내의 전파 지연 특성을 나타내었다. 또한, 최대 서비스 가용도를 갖는 위성 전송 시스템의 TWTA 동작은 0dB OBO가 적당하며, 위상 잡음 영향을 최소화하기 위해서는 0.707 damping 계수 및 40kHz 대역폭을 갖는 PLL 회로가 최적의 동작 특성을 나타내었다. 본 논문의 시스템 성능 분석 및 설계 파라미터 값들은 위성을 통한 고속 데이터 전송 시스템에 대한 설계 기준점으로 활용될 수 있다.

• Fisheries and Aquatic Sciences
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• 제16권4호
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• pp.253-260
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• 2013

We investigated the toxicological effects of Aroclor 1254 on the fertilized eggs, embryos and larvae of the olive flounder Paralichthys olivaceus. The survival rate and hatching success of the embryos decreased significantly in treated groups in an Aroclor 1254-dose-dependent manner. Significant differences were found at ${\geq}5{\mu}g/L$ Aroclor 1254 compared to the control group. Hatching success occurred at ${{\leq}}10{\mu}g/L$ Aroclor 1254, which was not significantly different to the control. Embryo malformation increased significantly at ${\geq}1{\mu}g/L$, and included yolk-sac and tail-flexure abnormalities. There was a significant decrease in the survival rate of the larvae at ${\geq}5{\mu}g/L$, which was accompanied by the malformations described above. Notably, concentrations as low as $1{\mu}g/L$ caused a significant increase in abnormalities in the larvae, including incidences of multi-focal hemorrhages, pericardial and yolk-sac edema, inhibition of swim bladder inflation and severe developmental delay. The responses to Aroclor 1254-induced toxicity were generally similar among fertilized eggs, embryos and larvae from three separate flounder hatcheries: Cheju Island, Yeosu and Chungnam, South Korea. These results indicate the high acute toxicity of Arolcor 1254 concentrations of which as low as $1{\mu}g/L$ in olive flounder larvae can affect unhatched embryos. To conclude, the average $LC_{50}$ values for Aroclor 1254 in the embryos and larvae were 50.92 and $3.08{\mu}g/L$, respectively. Additionally, the average $EC_{50}$ values, based on the rate of damage were 14.72 and 5.6$1{\mu}g/L$, respectively.

• 대한한방내과학회지
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• 제28권2호
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• pp.242-249
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• 2007

Backgrounds & Objectives : Yukgunjatanggranule (YGJT) ha been used for the treatment of functional dyspepsia, regarded as one of the gastric dysmotility diseases, but its mechanisms of cation are not yet well known, We investigated the effects of YGJT on gastric emptying and its mechanisms of action in rats. Methods : Gastric emptying was measured by glass beads (1mm in diameter) expelled from the stomach for 1 hour and 2 hours after administration ofnormal saline (NS) or YGJT 41.6mg/kg or 124.8mg/kg in rats. By the same method, gastric emptying was measured only for 2 hours after administration of NS of YGJT 124.8mg/kg in rats treated with atropine sulfate (1mg/kg, s.c), quinpirole HCl(0.3mg/kg, i.p.), NAME (NG-nitro-L-arginine methyl ester, 75mg/kg, s.c.) or cisplatin (10mg/kg, i.p.) to delay gastric emptying. Results : YGJT 124.8mg/kg improved gastric emptying more than NS or YGJT 41.6mg/kg (p=0.046). Under delayed gastric emptying, YGJT 124.8mg/kg improved gastric emptying in the group treated with cisplatin ($3.1{\pm}1.3$ vs. $6.6{\pm}3.1$, p=0.015), quinpirole HCl ($4.7{\pm}2.8$ vs. $5.5{\pm}5.6$, p=0.874) and NAME ($2.2{\pm}1.4$ vs. $4.7{\pm}6.0$, p=0.414), but aggravated it with atropine sulfate ($1.8{\pm}0.9$vs. $1.7{\pm}1.0$, p=0.957). Conclusions : YGJT improves gastric emptying through the cholinergic pathwas, and shows some effect against the toxicity of cisplatin. Therefore, we expect that it would be effective in relieving gastrointestinal symptoms in functional dyspepsia patients and cisplatin-treated patients.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.71-71
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• 2012

As the critical dimensions of integrated circuits are scaled down, the line width and spacing between the metal interconnects are made smaller. The dielectric film used as insulation between the metal lines contributes to the resistance-capacitance (RC) time constant that governs the device speed. If the RC time delay, cross talk and lowering the power dissipation are to be reduced, the intermetal dielectric (IMD) films should have a low dielectric constant. The introduction of Cu and low-k dielectrics has incrementally improved the situation as compared to the conventional $Al/SiO_2$ technology by reducing both the resistivity and the capacitance between interconnects. Some of the potential candidate materials to be used as an ILD are organic and inorganic precursors such as hydrogensilsequioxane (HSQ), silsesquioxane (SSQ), methylsilsisequioxane (MSQ) and carbon doped silicon oxide (SiOCH), It has been shown that organic functional groups can dramatically decrease dielectric constant by increasing the free volume of films. Recently, various inorganic precursors have been used to prepare the SiOCH films. The k value of the material depends on the number of $CH_3$ groups built into the structure since they lower both polarity and density of the material by steric hindrance, which the replacement of Si-O bonds with Si-$CH_3$ (methyl group) bonds causes bulk porosity due to the formation of nano-sized voids within the silicon oxide matrix. In this talk, we will be introduce some properties of SiOC(-H) thin films deposited with the dimethyldimethoxysilane (DMDMS: $C_4H_{12}O_2Si$) and oxygen as precursors by using plasma-enhanced chemical vapor deposition with and without ultraviolet (UV) irradiation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1344-1367
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• 2014

Mobile traffic is increasing a masse because of the propagation of the Internet and the development of wireless mobile technology. Accordingly, the Network Local Mobility Management (NETLMM) working group [1] of the Internet Engineering Task Force (IETF) has standardized Proxy Mobile IPv6 (PMIPv6) [2] as a protocol for accomplishing the transmissibility of mobile terminals. PMIPv6 is a network-led IP-based mobility management protocol, which can control terminal mobility without depending on the type of access system or the capability of the terminal. By combining PMIPv6 and the mobility of Session Initiation Protocol (SIP), we can establish terminal mobility and session mobility through a more effective route. The mobility function can be improved and the overlap of function reduced as compared to that in the case of independent operation. PMIPv6 is appropriate for a non-real-time service using TCP, and SIP is appropriate for a real-time service using RTP/UDP. Thus, in the case of a terminal using both services, an effective mobility management is possible only by using PMIPv6 together with SIP. In order to manage mobility in this manner, researches on PMIPv6-SIP are in progress. In line with this trend, this paper suggests a new PMIPv6-SIP architecture where when a mobile terminal conducts a handover, a network-led handover while maintaining the session without the addition of a special function or middleware is possible along with effective performance evaluation through mathematical modeling by comparing the delay and the packet loss that occur during the handover to the Pure-SIP.

• 한국산학기술학회논문지
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• 제16권4호
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• pp.2495-2504
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• 2015

본 연구는 도시정비사업의 효율적 추진에 영향을 미치는 갈등요인을 구축하고, 사업기간과 사업비용에 영향을 미치는 갈등요인을 PLS 회귀분석을 통해 도출하고자 한다. 자료 구축은 도시정비가 완료된 사업지역에 거주하고 있는 조합원, 세입자, 상인 등을 중심으로 하였다. 분석결과 사업기간의 경우 조합설립신청 및 인가, 철거 및 멸실신고, 사업시행계획 및 승인, 용역관련 이익집단의 사업지연 방해 등의 순으로 갈등요인이 중요한 것으로 도출되었으며, 사업비용의 경우 조합설립신청 및 인가, 매도청구, 이주, 철거 및 멸실신고, 관리처분계획 및 인가 등의 순으로 갈등요인이 중요한 것으로 나타났다.