구조화된 불확실성을 고려한 지능형 외팔보의 강인제어

권대규,방두열,소순선,유기호,이성철 전북대학교 공학연구원 ( 구 전북대학교 공업기술연구소 ) 2003 工學硏究 Vol.34 No.-

This paper presents the robust control of a composite beam using μ-synthesis. The natural frequencies of the composite beam featured by a piezo-film sensor and piezo-ceramic actuator are calculated by using the modal analysis method and then modal coordinates are introduced to obtain the state equations of the structural system. Two-natural frequency were considered in the modelling, because robust control theory which has inherent robustness to structured uncertainty is adopted to suppress the transients vibrations of a glass fiber reinforced(GFR) composite beam. A robust controller satisfying the nominal performance and robust performance is designed using μ-synthesis theory based on the structured singular value. Simulations and experiments were carried out with the designed controller and effectiveness of the robust control strategy was verified by results.

동측에 발생한 대퇴골 경부 및 간부 골절의 치료

권진우,김기환,문상호,공규민,손경태,이상훈,권태우 대한골절학회 2003 대한골절학회지 Vol.16 No.3

목적: 동측의 대퇴골 경부 골절과 간부 골절이 동반된 경우에서 수술적 치료에 대해 본원에서 실시한 수술 방법들의 결과를 분석하였다. 대상 및 방법: 수술 후 1년 이상 추시 관찰이 가능하였던 11례를 대상으로 하였으며 경부 골절은 Garden 제 1형이 3례, 제 2형이 6례, 제 3형이 1례, 제 4형이 1례였다. 간부 골절은 중간부가 7례, 원위부가 4례였다. 추시 기간은 최소 1년 이상으로 평균 33개월이었고 11례 전부가 남자였으며 나이는 22세에서 54세로 평균 38세였다. 각 수술 방법에 따른 수술시간을 측정하였으며 방사선학으로 골유합의 시기, 부정유합, 불유합 등을 평가하였고 임상적으로는 골절부의 동통 및 관절 운동장애를 평가하였다. 결과: 치료 방법으로는 경부는 다발성 피고정술이 8례, 활강압방 고 나사못고정술이 1례였으며 간부의 경우는 중간부는 역행적 Ender정 고정술이 4례 , 금속판 고정술이 1례, 재건상 골수강내 고정술이 2례, 역행적 금속정 고정술이 1례였고, 원위부는 금속판 고정술이 1례, 역행적 교합성 금속정 고정술이 3례였다. 평균 수술시간은 재건상 골수강내 골종술이 180분, 다발성 핀고정술 및 금속판 고정술이 220분, 다발성 핀고정술 및 역행적 골수강내 고정술이 200분이었다. 골유합 기간은 간부 골절의 경우 평균 5개월이었다. 경부 골절에 대한 합병증으로는 간부 골절에 대해서 Ender정 고정술을 한 1례와 간부에 금속판 고정술을 한 후 지연진단되어 경부에 다발성 핀고정술을 한 1례에서 대퇴골두에 무혈성 괴사증이 병발하였으며 재건상 골수강내 금속정 삽입술을 한 1례에서 수술시 경부 골절의 정복소실이 있었으며 간부 골절에 대한 합병증으로는 역행적 금속정 고정술을 한 2례 (Ender정 1례와 교합성 금속정 1례)에서 불유합이 생겨서 금속판 고정술 및 자가골이식술로 대치하였다. 그리고 Ender정 고정술을 한 1례에서 지속적인 슬관절 주위 동통이 있었다. 결론: 대퇴골 경부 골절과 동측의 간부 골절이 동반된 경우의 수술적 치료에서 재건상 골수강내 금속 고정술은 기술적으로 어려움이 많아서 경부와 간부의 치료를 각각 하는 것이 기술적으로 쉬웠다. 수술시는 경부 골절의 수술을 먼저 하여도 고정에 어려움이 없었으며 간부 골절은 분쇄 골절이 많기 때문에 견고한 내고정이 필요하였다. Purpose: The purpose of this study was to analysis the result of operative treatment in ipsilateral femur neck and shaft fracuture. Material and Methods: Eleven cases of ipsilateral femur neck and shaft fractures were operated and followed more than 1 year. There were 11 men and mean age at index operation was 38 years (range 22~54). In neck fracture there were 3 of type Ⅰ, 6 of type Ⅱ, and 1 of typeⅢ according to Garden classification, shaft fractures were located an middle 1/3 (7 cases), at distal 1/3 (4 cases). We evaluated the operation time, union time, nonunion, malunion, and clinical evaluation with pain and joint stiffness. Result: In neck fractures treatment methods were 8 of multiple pinning, 2 of reconstruction nail and 1 of CHS, in shaft fractures 2 of DCP, 7 of retrograde nailing (3 Ender nail, 4 interlocking nail). The mean operation time was 180 minutes in reconstruction nail, 220 minutes in multiple pinning and DCP and 200 minutes in multiple pinning and retrograde nailing. The mean time for shaft union was 5 months. The complications were 1 case of neck reduction loss during operation in reconstruction nailing group, 1 of persistant pain around knee in Ender nailing group. Conclusion: The author think that reconstruction nail fixation is technically difficult, thus neck and shaft fracture be fixed individually. Neck fracture can be fixed first without difficulty and shaft fractures should be fixed rigidly due to comminution.

단백뇨를 보이는 사구체 질환 및 당뇨병성 신병증에서의 Lp(a)

권태환,김준홍,조성,김석재,김용림,조동규,백미영 경북대학교 병원 1998 경북대학교병원의학연구소논문집 Vol.2 No.1

Background: Recently there has been evidences that serum Lp(a), an independent risk factor to atherosclerotic cardiovascular diseases, were increased in proteinuric disorders such as nephrotic syndrome and diabetic nephropathy. Methods: We intended to search of altered concentrations of Lp(a) in proteinuric disorder measuring serum Lp(a) concentrations with ELISA in 44 glomerulonephritic patients(25 nephrotic syndrome(NS), 19 non-nephrotic range proteinuric glomerulonephritis(GN), 25 diabetic nephropathy patients(DN), and 31 healthy controls(HC). Also, we compared Lp(a) concentration between glomerulonephritis patients and diabetic nephropathy patients with proteinuria of similar degree. Results: 1) There were significantly increased levels of total choesterol, triglyceride, and LDL-cholesterol in Ns compared to GN, DN, HC. 2) There were significantly increased concentrations of serum Lp(a) in NS compared to HC, but no signiicant difference in serum Lp(a) among NS, GN, and DN. 3) There was no significant difference in serum Lp(a) concentrations between NS & DN with 24 hour urine protein greater than 3.0g. 4) There was no significant difference in serum Lp(a) concentration between GN with 24 hour urine protein greater than 0.5g and less than 1.5g and DN with proteinuria of simial degree. 5) In glomerulonephritis patients, there was negative correlation between serum Lp(a) concentration and serum albumin level but correlation with 24 hour urinary protein, total cholesterol, Ldl-cholesterol, and HDL-cholesterol was not shown. In diabetic nephropathy, there was no significant correlation among serum Lp(a) concentration and all parameters including serum albumin, 24 hour urinary protein, and other lipid profiles. Conclusion: The present study confirmed that patients with nephrotic syndrome of diverse etiologies have makedly increased plasma level of Lp(a), in conjunction with other lipid abnormalities. However, this study shows no difference in Lp(a) concentrations between diabetic nephropathy and glomerulonephritis with similar degree of proteinuria.

Stented Graft의 임상경험

권태원,김호성,김도균,성규보,조용필,김건언 대한혈관외과학회 2000 Vascular Specialist International Vol.16 No.2

Purpose: Endovascular repair is a alternative treatment with favorable short-term result, but long term results are not available compared to standard operation. The authors have reviewed experiences of Asan Medical Center on stented graft, performed from Aug. 1998 to Feb. 2000, and the results as to age, operative indication, clinical condition, anatomic location, complication, follow-up are reported. Method: Seven patients who has received stented graft between Aug. 1998 and Feb. 2000 are reviewed retrospectively. Result: Of the seven patients, 6 were male and 1 was female. The mean age was 46.4 years (17~71). Indication for stented graft were two pseudoaneurysms, two iatrogenic arterio-venous fistulas, one thoracic aorta aneurysm, one abdominal aortic aneurysm, and one iliac artery occlusion with blue toe syndrome. Three different types of stented graft devices were utilized: Dacron-covered nitinol stented graft (made by the Asan Medical Center medical device team), Vanguard II (by Boston Scientific Corp.), and PTFE with nitinol stented graft (by Tae-woong). There was no perioperative mortality, and the technical success was achieved in five cases (71%). The patency at 14-month were 1009o (5/5). Two immediate complications are hemorrhage due to iliac & femoral artery avulsion requiring emergency bypass grafting, and deployment failure of stented graft requiring removal of retained graft device. Conclusion: Stented graft may be utilized even in complicated vascular situation but will need further development of device and more experience to prevent possible catastrophic complication. Indication should be decided by team approach and vascular surgeon should be prevent or participate during the procedure.

전자상거래를 이용한 관광산업의 활성화 방안

권태윤,박성규 경운대학교 산업기술연구소 2001 産業技術硏究論文誌 Vol.4 No.1

As the growth of the electronic commerce(EC) and the world wide web(WWW) is continued, internet-based electronic commerce is getting a continuous attention. This paper discusses on the impact of electronic commerce related the tourist industry. The authors anticipate that changes in the travel distribution process brought about by the electronic commerce and other information technologies will result in travel agencies experiencing lower business profitability. Based on this background, the paper further suggests improving plans that could be undertaken to address the situation.

부분적으로 유체가 채워진 원통형 관내의 외팔보 진동특성에 관한 실험적 연구

권대규,유계형,소순선,이성철 전북대학교 공학연구원 ( 구 전북대학교 공업기술연구소 ) 2003 工學硏究 Vol.34 No.-

This paper presents the vibration characteristics of an intelligent cantilever beam in contact with fluid using PZT actuator and PVDF film. The effect of liquid level on free vibration of composite beam in a partially liquid-filled circular cylinder is investigated. The dynamic behaviors of a flexible beam-water interaction system are examined. The coupled system is subject to an undisturbed boundary condition in the fluid domain. In the vibration analysis of wetted beam, the decoupled analyses between beam and fluid have been conventionally employed by considering firstly the composite beam vibration in air and secondly performing the correction taking account for surrounding fluid effects. That is, this investigation was to look at how natural frequencies, mode shapes, and damping are affected by liquid level variations. Using the coupled modal reanalysis method employing the governing equations and the clamped-free and free-free boundary conditions, the vibration analysis of beam in contact with fluid is performed. We also carried out the experimental verification about reliability of theoretical methods to inclusive vibration analysis of the fluid-structure system with PZT actuator and PVDF film. It was found that the coupled natural frequencies decrease with the fluid level for the identical composite beam due to added mass effect.

오존처리에 의한 하수슬러지의 감량화

권재현,류성호,박기영,안규홍,염익태,이용훈 대한상하수도학회 2002 상하수도학회지 Vol.16 No.2

The effects of ozone treatment on the dewaterability of activated sludge wasted from a sewage treatment plant were investigated in this study. Following ozone treatment, sludge was dewatered using a pressure fitter. The sludge filterability evaluated by SRF deteriorated with ozone dosage at relatively low ozone doses due to sludge solubilization and particle size decrease. However, at ozone doses higher than 0.6gO_3/gSS, the SRF of the ozone treated sludge became comparable with the value for the sludge without ozone treatment. It is suggested that the oxidation of the viscous, high molecule organics attached at cell surface reduces the surface charge of sludge particle and promotes flocculation at relatively high ozone doses. Ozone treatment also cause the release of bound water trapped inside cells or flocs, resulting in significant reduction of cake water content after dewatering. In terms of cake volume, more than 70% reduction was obtained at 0.6gO_3/gSS. These observations suggest that ozone treatment has potential to significantly enhance sludge dewaterability and to produce a more compact cake without severe deterioration of its filterability.

동남참게, Eriocheir japonicus (De Haan)의 種苗生産에 關한 生物學的 基礎硏究 : 2. Influence of Temperature and Salinity on the Growth of Larvae 2. 幼生의 成長에 따른 水溫과 鹽度의 影響

權晉洙,李福奎,文泰錫 동의대학교 기초과학연구소 1994 基礎科學硏究論文集 Vol.4 No.1

For the development of seedling production techniques of the freshwater crab Eriocheir japonicus, the effects of salinity and temperature on the growth of larvae of the crab were studied. Embryos hatched out as zoea larvae were measured 0.421 mm in average carapace length. Five zoea stages needed 16~26 days for metamorphosis from zoea to megalopa at 22℃ and 24.5‰. The average carapace length of the 5th zoea was 1.16 mm and that of the megalopa larvae was 1.89 mm. Each zoea stage could be identified based on both the number of plumosed seatae on the exopodite of maxilliped, and the number of spines on the posteroinner margin of telson and also based on the rudimentary pleopods appearence. Zoea larvae fed rotifers and Artemia nauplii were healthy and metamorphosing rate from zoea to megalopa was 80~90% at 22~26℃ and 17.5~31.5‰. The relationship between larval period(Y in days) and water temperature (X in ℃) is expressed as Log Y=3.8604-1.91735 Log X. Water temperature and salinity ranges for better survival and metamorphosis of the larvae was 22℃~26℃ (optimum at 26℃) and 17.5‰~31.5‰(optimum at 24.5‰), respectively. The duration of larval stages tend to longer as salinity levels deviated from optimum particulaly at lower porendtion. All zoea larvae did not survive in freshwater

전기화학법에 의해 형성된 Ti 양극산화피막의 특성

김태영,손원우,권태엽,강인규,김교한 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.3

The effects of electrolyte concentration and current density on the behaviour of volt-time curve of the anodizing, morphology, roughness, crystallinity and composition of the oxide layer were studied. Microstructural morphology, crystallinity, composition and surface roughness of oxide layer were analyzed by observed by scanning electron microscopy(SEM) and X-ray diffractometry(XRD), Energy-dispersive spectrometer(EDS), Electron Probe Micro Analyzer(EPMA)and roughness tester, respectively. The results of this study showed that the voltage incresed as the anodizing time increase. The growth of the oxide film developed a barrier layer to a pore-like layer with an increasing of current density, arising a spark discharge. On the morphology of anodic oxide layer the number and size of porosity was increased by increasing anodizing time at a constant concentration of electrolyte. The size of porosity and the roughness of the anodic oxide layer were increased by the increasing of concentration of electrolyte. The anodic oxide layer obtained in the conditions of this experiment was identified as anatase. The crystallinity of oxide layer was decreased by increasing the concentration of electrolyte at constant current density, and increased by the increasing current density at constant electrolyte concentration. In the EPMA analysis of anodic oxide layer, the concentration of phosphorous was increasing the electrolyte concentration and increasing the final voltage at constant electrolyte concentration, The ratio of O/Ti of the oxide layer obtained in this experiment was near 2 confirming this oxide layer was TiO₂

코쉬섬 1차 반복 형태의 마이크로스트립 패치 안테나에 관한 연구

김일권,유태훈,육종관,박한규 연세대학교 전파통신연구소 2001 電波通信論文誌 Vol.5 No.1

In this paper, the microstrip patch antenna applying the koch island fractal geometry is introduced in order to reduce the antenna patch size. By space-filling property of fractal geometry, the microstrip patch applying koch island has low frequency compared with square patch antenna. In the case of 1st order iteration patchs are investigated by simulator and experiment. Through this, it is found that as the fractal iteration factor increase, the resonant frequency of koch island patch is lower. therefore koch island patch antenna can reduce patch size compared with square patch antenna. and The fabricated patch antenna is matched by using quarter wave length impedance transformer and return loss and radiation patterns are measured. The measurement result shows that the copolarization pattern of koch patch is similar to that of square patch. The cross polarization power level is -15∼-20dB.