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A Path-level Smooth Transition Method with Curvature Bound between Non-smoothly Connected Paths
최윤종(Yun Jong Choi),박부견(Poo Gyeon Park) 대한전자공학회 2008 電子工學會論文誌-SC (System and control) Vol.45 No.4
연속적인 경로 사이를 부드러운 곡선으로 잇기 위해서 기존의 로봇 제어기들은 일반적으로 연속적인 경로를 시간 축에서 합성하는 방법을 사용해 왔다. 하지만 이런 방법은 다음과 같은 두 가지 단점을 내재하고 있다. 천이 경로의 형태가 연접하게 생성될 수 없다는 점과 천이하는 동안 속력을 제어할 수 없다는 점이 그것이다. 이러한 문제점들을 극복하기 위해서 본 논문은 매끄럽지 않게 연결된 두 경로들을 부드럽게 잇기 위해 곡률이 제한된 새로운 천이 궤적 생성 방법을 제시하고자 한다. 실험 결과는 기존의 방법들보다 천이 궤적이 더 부드럽게 생성되는 것을 보여주며, 또한 보장된 곡률의 제한 수준은 0.02 ~ 1임을 보여준다. For a smooth transition between consecutive paths, conventional robot controllers usually generate a transition trajectory by blending consecutive paths in a time coordinate. However, this has two inherent drawbacks: the shape of a transition path cannot be designed coherently and the speed during transition is uncontrollable. To overcome these problems, this paper provides a path-level, rather than trajectory-level, smooth transition method with the curvature bound between non-smoothly connected paths. The experiment results show that the resultant transition trajectory is more smoothly connected than the conventional methods and the curvature is closely limited to the desired bound within the guaranteed level (0.02∼1).
수술 후 잔위에서 Helicobacter pylori의 분포와 역할
최윤종 ( Yeun Jong Choi ),김현수 ( Hyun Soo Kim ),박동훈 ( Dong Hoon Park ),김문영 ( Moon Young Kim ),백순구 ( Soon Koo Baik ),이동기 ( Dong Ki Lee ),권상옥 ( Sang Ok Kwon ),박광화 ( Kwang Hwa Park ) 대한소화기학회 2003 대한소화기학회지 Vol.41 No.3
Background/Aims: The distribution of Helicobacter pylori (H. pylori) and its effect on postoperative remnant gastritis has not been clearly investigated. Thus, we carried out this study to examine H. pylori positive rate in the body and cardia and to assess the role of H. pylori on the pathogenesis of remnant gastritis. Methods: Eighty-two patients who had undergone gastric surgery (Billroth I, II) were studied. Four biopsy specimens were obtained from the cardia and oral side of anastomosis for histological analysis and CLO test. The histological grades of gastritis were determined by four parameters of visual analogue scales adopted by updated Sydney system. Results: The overall positive rate of H. pylori was 48.8%. Among the infected patients, H. pylori positive rate was significantly higher in the cardia than in the body (87.5% vs. 37.5%, p< 0.01). The H. pylori positivity was not associated with age, sex, primary disease, type of surgery, chemotherapy, and postopertive interval. The gastritis scores of inflammatory cell infiltration were higher in H. pylori positive patients. However, the scores of atrophy and intestinal metaplasia were not significantly different between the two groups. Conclusions: The H. pylori positive rate is higher in the cardia than in the body of postoperative remnant stomach. It suggests that H. pylori may play an important role in remnant gastritis through acute and chronic inflammatory cell infiltration. (Korean J Gastroenterol 2003;41:177-182)
불확실한 초기치를 갖는 반복시스템에 대한 유한구간 추종제어
최윤종(Yun Jong Choi),윤성욱(Sung Wook Yun),이창희(Chang Hee Lee),조재영(Jae Young Cho),박부견(PooGyeon Park) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.10
Repetitive systems stand for a kind of systems that perform a simple task on a fixed pattern repetitively and are widely spread in industrial fields. Hence, those systems have been of much interests by many researchers, especially in the field of iterative learning control (ILC). In this paper, we propose a finite-horizon tracking control scheme for linear time-varying repetitive systems with uncertain initial conditions. The scheme is derived both analytically and numerically for state-feedback systems and only numerically for output-feedback systems. Then, it is extended to stable systems with input constraints. All numerical schemes are developed in the forms of linear matrix inequalities. A distinguished feature of the proposed scheme from the existing iterative learning control is that the scheme guarantees the tracking performance exactly even under uncertain initial conditions. The simulation results demonstrate the good performance of the proposed scheme.
간경변 환자에서 말초신경병증의 임상적 특성과 신경전도검사 소견
최윤종 ( Yeun Jong Choi ),백순구 ( Soon Koo Baik ),석기태 ( Ki Tae Suk ),김정민 ( Jung Min Kim ),지명관 ( Myeong Gwan Je ),김현수 ( Hyun Soo Kim ),이동기 ( Dong Ki Lee ),권상옥 ( Sang Ok Kwon ),박기철 ( Ki Chul Park ),이지용 ( Ji 대한소화기학회 2003 대한소화기학회지 Vol.41 No.6
Background/Aims: In liver cirrhosis, symptoms such as paraesthesia and numbness are associated with peripheral neuropathy (hepatic neuropathy). The prevalence and nerve conduction study (NCS) of hepatic neuropathy have not been reported yet in Korea. This prospective study was designed to evaluate the prevalence, clinical characteristics, and NCS of hepatic neuropathy, and to compare peripheral neuropathy of alcoholic cirrhosis with that of nonalcoholic cirrhosis. Methods: Seventy-three patients with liver cirrhosis underwent neurological evaluations including a history and neurological examinations relevant to the peripheral nervous system. NCS was performed in all subjects. Results: Peripheral neuropathy was found in 53.4% of the patients. Sensory neuropathy was observed more frequently than motor neuropathy on NCS. Overall, the pattern of neuropathy was axonal degeneration. There was no difference in the characteristics of peripheral neuropathy between the patients with alcoholic cirrhosis and the patients with nonalcoholic cirrhosis. Among 29 patients with neurologic symptom and sign, 22 patients (76%) showed an abnormality in NCS. Conclusions: The prevalence of peripheral neuropathy is 53.4%. This study suggests that symptoms such as numbness or paraesthesia in patients with cirrhosis are related to peripheral neuropathy. (Korean J Gastroenterol 2003;41:486-492)
최윤종(Yunjong Choi),김홍성(Hongsung Kim),박정서(Jungseo Park),김문헌(Munheon Kim) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.11_1
This study introduced the bulk combustion systems instead of the conventional gasoline spark ignition system and diesel compression ignition system. To achieving both high efficiency, without ignition systems to the conventional single cylinder diesel engine, established the inlet-air heating and control systems for the heating and controlling of inlet-air.<br/> The lean limit of air-fuel ratio improved by the inlet-air heating with the compression ignition combustion systems' and the allowable air-fuel ratio extended to 63 when the temperature of the inlet-air was 170 ℃ and the engine speed 1000 rpm.<br/> The cycle maximum pressure and the brake mean effective pressure increased to proportional, when the air-fuel ratio was richer.<br/> The brake specific fuel consumptions increased largely at the air-fuel ratio was above 45 and affected strongly by the inlet-air heating temperature.<br/> The maximum brake thermal efficiency showed at the air-fuel ratio was 35 and decreased in case the leaner region and improved the higher inlet-air heating temperature.<br/> The maximum heat release rate increased in according to decreased and advanced the<br/> accurance period of the maximum heat release rate.<br/> Also, as showed the mass burned rate, the burning period shorted and established the rapid combustion in according to the air-fuel ratio decreasing.<br/>
최윤종(Choi, Yoon-Jong),이준성(Lee, Joon-Seong) 한국산학기술학회 2011 한국산학기술학회논문지 Vol.12 No.1
본 논문은 기존의 스파크 점화 방식이 아닌 bulk combustion 방식을 도입하여 별도의 점화장치 없이 상용 단기통 디젤기관에 유입되는 흡입공기를 가열 및 제어하여 흡기관에 분사되는 가솔린연료의 압축착화성을 향상시킴 으로서 기관작동을 가능하게 하였다. 제동열효율의 최대값은 공기-연료비가 35부근에서 나타나며, 35이상의 영역에서 는 급격히 감소하고 흡입공기 가열온도가 올라갈수록 제동열효율은 증가한다. 따라서 공기-연료비를 감소시키면서 흡 입공기의 가열온도를 상승시키는 방식이 열효율 측면에서 효과적이라는 것을 알 수 있다. In this study, it made to run conventional single direct injection(DI) diesel engine, which adapted bulk combustion system not following spark ignition system without any ignition apparatus. It was heated and controlled inlet-air into conventional single DI diesel engine. The maximum value of brake thermal efficiency was at 35 region of air-fuel ratio. On the contrary, when the region of air-fuel ratio leaner than 35, brake thermal efficiency was decreased suddenly. And brake thermal efficiency was increased as much as inlet-air heating temperature increased. So, when air-fuel ratio was decreased and inlet-air heating temperature was higher, the engine was in optimal operation condition.