HSDPA 시스템에서 선택적 지연 기반의 N-채널 SAW ARQ

박형주,임재성,Park Hyung-Ju,Lim Jae-sung 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.10A

본 논문에서는 N-채널 SAW(Stop and Wait) ARQ 재전송 기법을 채택하고 있는 HSDPA 시스템에서 HS-DSCH 채널의 성능 향상을 목적으로 선택적 패킷 지연(SPD :Selective Packet Delay) 기법을 제안한다. SPD 기법은 무선 채널 상태에 따라 적응적으로 패킷 전송을 제어하는 방법으로 채널 상태가 나쁜 경우에는 해당 패킷 전송을 일정시간 동안 강제 지연하고 대신에 해당 타임 슬롯을 채널 상태가 양호한 다른 사용자에게 할당해 주는 기법이다. 따라서 제안하는 기법은 버스트 에러 환경에서 연속적인 패킷 손실로 인해 발생하게 되는 긴 재전송 지연을 효과적으로 줄일 수 있는 특징을 가진다. 또한 SPD 기법에 효율적으로 적용될 수 있는 SPD-LDPF(Long Delayed Packet First)와 SPD-DCRR(Deficit Compensated Round Robin)의 두 종류의 패킷 스케줄링 기법을 제안한다. 시뮬레이션 결과, 제안한 기법은 패킷 평균지연 특성, 처리량 성능, 그리고 사용자간 공평성에서 모두 우수한 성능을 보임을 확인하였다. In this paper, we propose a SPD(Selective Packet Delay) scheme to improve the performance of High-Speed Downlink Shared Channel(HS-DSCH) employing N-Channel Stop and Wait retransmission scheme in High Speed Downlink Packet Access(HSDPA) system. The proposed SPD coordinates packet transmissions according to the channel condition. When the channel condition is bad, packet transmission is forcedly delayed, and the designated time slot is set over to other users in good channel condition. Hence, the SPD is able to reduce the average transmission delay for packet transmission under the burst error environments. In addition, we propose two packet scheduling schemes called SPD-LDPF(Long Delayed Packet First) and SPD-DCRR(Deficit Compensated Round Robin) that are effectively combined with the SPD scheme. Simulation results show that the proposed scheme has better performance in terms of delay, throughput and fairness.

레이저홍채절개술 단독 치료와 아르곤레이저주변홍채성형술 병용 치료 후 전안부빛간섭단층촬영 결과 비교

박형주,박기호,김석환,김태우,김동명,Hyung Ju Park,MD,Ki Ho Park,MD,PhD,Seok Hwan Kim,MD,PhD,Tae Woo Kim,MD,PhD,Dong Myoung Kim,MD,PhD 대한안과학회 2011 대한안과학회지 Vol.52 No.5

Purpose: To compare the changes in angle parameters after laser peripheral iridotomy (LPI) alone versus LPI and ALPI (argon laser peripheral iridoplasty) in primary angle closure patients by using anterior segment optical coherence tomography (AS-OCT). Methods: A total of 25 eyes from 17 patients with narrow angles were enrolled in this present study. Eleven eyes in the LPI treatment group and 14 eyes in the LPI and ALPI combined treatment group were evaluated using AS-OCT. The anterior chamber depth (ACD), angle opening distance at 500 μm (AOD 500) and 750 μm (AOD 750), angle recess area at 500 μm (ARA 500) and 750 μm (ARA 750), trabecular-iris space area at 500 μm (TISA 500) and 750 μm (TISA 750), trabecular-iris angle (TIA) were measured. The pre- and post-treatment parameters were compared in each group. The parameter changes after laser treatment were also compared. Results: AOD 500, AOD 750, ARA 500, ARA 750, TISA 500 and TISA 750 except ACD significantly increased following LPI treatment (p = 0.013, p = 0.010, p = 0.008, p = 0.003, p = 0.006, p = 0.003, p = 0.013, respectively, Wilcoxon signed rank test) and LPI and ALPI combined therapy (p = 0.001, p = 0.001, p = 0.001, p = 0.001, p = 0.001, p = 0.001, p = 0.001, respectively, Wilcoxon signed rank test). The AOD 500 difference, TISA 500 difference, and TISA 750 difference were significantly greater after LPI and ALPI combined therapy than after LPI treatment alone (p = 0.112, p = 0.147, p = 0.049, p = 0.037, respectively, Mann-Whitney U-test). Conclusions: The results from the present study showed LPI alone or LPI and ALPI combined therapy significantly widened the anterior chamber angle and combined therapy showed greater effect than LPI alone. J Korean Ophthalmol Soc 2011;52(5):566-573

당뇨황반부종의 임상진단과 망막두께분석기의 비교

박형주,신선영,김준현,Hyung-Ju Park,Sun-Young Shin,Joon-Hyun Kim 대한안과학회 2005 대한안과학회지 Vol.46 No.8

Purpose: To evaluate the correlation between diabetic macular edema diagnosed with stereoscopic slit-lamp and retinal thickness analyzer (RTA). Methods: Diabetic macular edema diagnosed with stereoscopic slit-lamp was compared to indices of RTA in 50 eyes of 32 persons which were diagnosed clinically with diabetic retinopathy. Results: From stereoscopic slit-lamp results, diabetic macular edema was present in 39 of 50 eyes, and absent in 11 of 50. Foveal average thickness out of the RTA indices was 209.7±58.5 μm from observing diabetic macular edema clinically and 199.4±47.3 μm from not observing diabetic macular edema clinically. Statistically significant differences were found in average foveal thickness between the 2 groups (p=0.013). Conclusions: RTA appears to serve as a useful and sensitive tool for the diagnosis of diabetic macular edema.

튜브 결찰 및 스텐트 방식에 따른 방수유출장치 내 유동저항의 평가

박형주,박기호,김석환,김태우,김동명,Hyung Ju Park,Ki Ho Park,Seok Hwan Kim,Tae Woo Kim,Dong Myoung Kim 대한안과학회 2011 대한안과학회지 Vol.52 No.5

Purpose: To evaluate the flow resistance though the tube in a glaucoma drainage implant using various tube ligation methods. Methods: To measure the flow resistance, the following tube ligation methods were designed and tested: Type 1: no ligation of Ahmed valve tube. Type 2: ligation of Ahmed valve tube with 8-0 Vicryl. Type 3: ligation of Molteno tube and a 6-0 Vicryl as an intra-luminal stent with 8-0 Vicryl. Type 4: ligation of Ahmed valve tube and three strands of 8-0 nylon as extra-luminal stents with 8-0 Vicryl. Type 5: ligation of Ahmed valve tube and a 6-0 Prolene as an extra-luminal stent with 8-0 Vicryl followed by removal of the Prolene for partial ligation. Results: The pressure was maintained under 0.143 mm Hg in type 1. In type 2, the pressure increased to 6.688 mm Hg and dropped to approximately 6.384 mm Hg. In type 3, the pressure was maintained at 5.396 mm Hg which decreased to 3.572 mm Hg after stent removal. In type 4, the pressure was maintained at 5.700 mm Hg which dropped to 5.472 mm Hg after the 1st stent removal, to 5.016 mm Hg after the 2nd stent removal and to 4.180 mm Hg after the 3rd stent removal. In type 5, the pressure increased to 6.384 mm Hg and decreased to 5.624 mm Hg. Conclusions: The tube ligation along with extra-luminal stents followed by staged removal may provide prevention of hypotony and staged control of intraocular pressure after a glaucoma implant operation. J Korean Ophthalmol Soc 2011;52(5):610-617

IV와 HIV 절연 전선용 PVC 절연재료의 수명 예측

박형주 ( Hyung-ju Park ) 한국안전학회(구 한국산업안전학회) 2019 한국안전학회지 Vol.34 No.1

Weight and elongation changes of IV and HIV insulations were measured simultaneously at several given temperature of 80℃, 90℃ and 100℃. And the lifetime was predicted using the Arrhenius model. Based on the initial weight values, a 50% elongation reduction was seen at 6.96% for the IV insulation and 10.29% for the HIV insulation. The activation energy from the slope of the lifetime regression equation was calculated as 92.895 kJ/mol(0.9632 eV) for the IV insulation and 95.213 kJ/mol(0.9873 eV) for the HIV insulation. Also, the expected lifetime at the operating temperature of 30℃ to 90℃ is 2.02 to 94.32 years, and longer lifetime was predicted on HIV insulated wires than on IV insulated wires. As a result, it was found that the thermal characteristics of the HIV insulated wires were about 12.44% better than those of IV insulated wires under the same conditions of use.

화점높이 변화에 따른 Pool Fire의 연소특성

박형주(Park, Hyung-Ju),차종호(Cha, Jong-Ho) 한국산학기술학회 2010 한국산학기술학회논문지 Vol.11 No.11

화점높이 변화에 따른 풀 화재의 연소특성을 알아보기 위하여 인화성액체인 메탄올과 노르말 헵탄을 100㎜ ×100㎜×50㎜ 크기의 사각형 용기에 내에 넣고 연소실험을 하였다. 용기의 재질은 스테인레스를 사용하였다. 연소시 간, 질량감소속도, 화염온도, 화염높이 및 외부에서 화염으로의 공기유입속도 등을 측정하였으며 연소시 화염의 거동 은 비디오카메라를 이용하여 촬영하였다. 실험을 통해서 화점의 높이가 증가할수록 외부에서 화염으로 유입되는 차가 운 공기의 유입량이 증가하여 풀 화재의 연소특성이 감소함을 확인 할 수 있었다. This study is intended to understand flame behavior of the pool fire by height of fire source. Liquid fuels were methanol and n-Heptane which are used in many studies of pool fire. Size of vessel was 100㎜×100 ㎜×50㎜ and the vessel was made by stainless steel. Combustion time, mass loss rate, flame temperature, flame height and air entrainment rate from the outside to flame were measured, and flame behavior was visualized with video camera. Based on the experiment, it was found that combustion characteristics of pool fire was decreased according to increase of height of fire source because entrainment volume of relative cold air was increased from the outside to flame.

색차 측정이 가능한 전자문서용 스캐너 인증 평가도구 개발

박형주(Park Hyung-Ju),하동환(Har Dong-Hwa) 한국색채학회 2009 한국색채학회 논문집 Vol.23 No.4

표면촉진화학성장법을 이용한 다중선형 나노갭 전극의 제작

박형주(Hyung Ju Park),지영식(Young Shik Chi),이남희(Nam Hee Lee),우병칠(Byung-Chill Woo),윤완수(Wan Soo Yun) 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.6

주가동조화현상과 재무분석가의 목표주가

박형주 ( Hyung Ju Park ),조중석 ( Joong-seok Cho ) 한국회계학회 2021 회계학연구 Vol.46 No.5

본 연구는 주가동조화현상과 재무분석가의 목표주가 예측과의 관계에 대해 연구하였다. 구체적으로, 주가동조화 수준이 재무분석가의 목표주가 예측능력에 어떠한 영향을 주는지에 대해 분석하였다. 주가동조화현상이 높다는 것은 개별 기업의 주가에 해당기업에 대한 정보가 충분히 반영되어 해당기업의 주가가 기업의 내재가치에 근접하다는 것을 의미한다(Pontiff 2006). 따라서 본 연구에서는 주가동조화현상이 높을수록 재무분석가의 해당 기업에 대한 정보수집 및 가치평가가 용이할 것으로 예상하고 이에 따라 주가동조화현상이 재무분석가의 목표주가 예측에 긍정적인 영향을 미칠 것으로 예상한다. 위와 같은 가설을 검증하기 위하여 본 연구는 2001년부터 2016년까지 한국 유가증권시장에 상장된 12월 결산법인을 대상으로 분석하였으며 최종 기업-연도 표본수는 2,378개이다. 개별기업의 주가동조화 정도를 측정하기 위하여 Roll(1988)과 Piotroski and Roulstone(2004)의 연구에서 사용되었던 R2 측정치를 사용하였고, 재무분석가의 예측능력을 측정하기 위해서는 재무분석가의 목표주가 예측정확성(TPAFE)과 실제주가의 목표주가 달성여부(TPMETEND, TPMETANY)를 사용하였다. 실증분석 결과는 다음과 같다. 주가동조화 수준이 높을수록 재무분석가의 목표주가 예측정확성이 높아지고 예측기간 동안 실제주가가 목표주가에 도달하는 빈도가 증가하는 것으로 나타났다. 또한 추가분석에서는 개별기업별 정보환경의 특성을 고려한 후에 주가동조화 수준이 재무분석가의 목표주가 예측능력에 미치는 영향을 살펴보았다. 분석결과, 이익변동성, 정보비대칭, 기업규모 및 재무분석가의 수 등을 통제한 후에도 주가동조화현상이 높을수록 재무분석가의 목표주가 예측능력이 높은 것으로 나타났다. 본 연구의 결과는 주가동조화 현상이 높을수록 즉, 개별기업 정보가 주가에 반영되는 정도가 높을수록 해당 기업의 정보효율성이 증가하여 재무분석가의 목표주가 예측능력에 긍정적인 영향을 준다는 것을 의미한다. This study investigates how the level of stock return synchronicity affects the financial analyst's ability to predict the target price. High stock return synchronicity means that the stock price of an individual company sufficiently reflects the information about the company to approximate the company's fundamental value and is less likely to deviate from it (Pontiff 2006). Accordingly, we posit that the level of stock return synchronicity of a firm is positively associated with the analysts’ target price forecasting ability. To test our hypotheses, we adopt the R2 measure used in the study of Roll (1988) and Piotroski and Roulstone (2004) to gauge the degree of stock return synchronicity of individual firms. As our financial analyst's forecasting ability measures, we use financial analyst's target price prediction accuracy (TPAFE) and target price achievement (TPMETEND, TPMETANY). We find that the higher the level of stock return synchronicity, the more accurate the financial analyst's target price predictions, and the frequency at which the actual stock price reaches the target price forecast anytime during or at the end of the year increases. After controlling for earnings volatility, information asymmetry, company size, and the number of financial analysts, our results corroborate the results above. The results of our study indicate that the higher the stock return synchronicity, that is, the higher the degree to which individual company information is reflected in the stock price, the higher the information efficiency of the firm, which positively influences the target price forecasting ability of the financial analysts.

무선 멀티미디어 서비스를 위한 적응적인 2 차원 FEC 인코딩/디코딩 알고리즘

박형주(Hyung-Ju Park),오세훈(Se-Hoon Oh),임재성(Jae-Sung Lim) 한국통신학회 2003 한국통신학회 학술대회논문집 Vol.2003 No.7