부하에 대한 PI제어기의 안정화를 위한 전보상기의 구현

하달영,권태익,김승철,임영도 동아대학교 정보기술연구소 2001 情報通信硏究所論文誌 Vol.8 No.2

In this paper, Pre-compensator is proposed to solve the problem of PI controller with fixed parameter according to load. This problem has been solved by using various adaptive control methods and intelligent control methods. The distinguished feature of the proposed controller is to have simple structure and it can control effectively for steady state error. To prove this, the performance is evaluated by comparative experiment for system using PI control with pre-compensation and PI controller with fixed parameter. Experiment in the velocity control of the 3-phase induction motor is performed.

KAIST 인사평정시스템 : 특징, 문제점 및 개선방안

하태권,조경호,진재구 서울産業大學校 2005 논문집 Vol.54 No.4

This study aims to analyze characteristics, problems and solutions of performance appraisal system of the Korea Advanced Institute of Science and Technology (KAIST). Regulations and statistical data of KAIST performance appraisal system of employees except faculty members are analyzed, and all the target group members are surveyed. Some of them are selected for in-depth interview. Major problems found in this study are as follows: lack . of connection between performance appraisal system and organizational strategic development plans including overall human resource management system, lack of operational definition of evaluation factors and criteria, confusion in contents among evaluation factors, irrational weight distribution among evaluation factors, individual-focused performance appraisal where cooperative team efforts are neglected, subjective evaluation, and prohibition of disclosing results of appraisal to the rates. These problems are identified to be a main cause for a high level of dissatisfaction of employees with performance appraisal system. Based on the above-mentioned problems, a variety of recommendations are suggested to improve the KAIST performance appraisal system.

고강도 인바합금의 석출 및 변형거동

하태권,정효태 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-

Thermodynamic equilibrium of Fe-36Ni-2.7Mo-2Co-1Cr-0.32C-0.06Nb base Invar alloy during solidification has been investigated using Thermo-Calc in this study, revealing that equilibrium phases which can be formed are two kinds of MC-type precipitates, I.e Nb-15.4Mo-11.25C-4.2V and Mo-8Fe-6.4C-1.8V-1.1Nb, and MoC carbide. The latter stoichiometric carbide was expected to be formed at relatively lower temperature below 770℃. Microstructure observation revealed that the coarse precipitate existing in the Fe-36Ni-2.7Mo-2Co-1Cr-0.32C-0.06Nb alloy produced was Mo-rich non-equilibrium phase presumably formed during casting, which can be resolved by the heat treatment, Two paths of hot rolling process have been conducted employing different soaking temperatures. High strength above 1000MPa and 40% of elongation were obtained at room temperature in both cases. Hot-rolled Invar alloy was successfully drawn at room temperature from 6 mm to 4 mm in diameter.

浸透水에 의한 모래層의 破壞에 관한 硏究

權武男,李相昊,柳泰夏 慶北大學校 1991 論文集 Vol.51 No.-

In order to investigate seepage failure of sand layer and analyze the effect of the loaded filter constructed on the top of the layer, small scale laboratory tests were carried out on 6 kinds of grain sized sand layers with and without loaded filter of variations of thickness. The results obtained are as follows; 1. The relationship between critical velocity and critical gradient had positive correlation and appears to be linear equation regardless of grain size of the sand. 2. The critical velocity had a trend to increase linearly as grain size of the sand get to be bigger. And the critical velocity in the effective size of 10mm appeared to be about 15 times of that of the 0.2㎜ effective size. 3. The critical velocity was increased according to increase the thickness of loaded filter. And the critical velocity in the 8㎝ thick of loaded filter showed to be 2 times as comparison to the case of no loaded filter. In virtue of the conclusion above, the seepage force can fail sand layer seriously but the stability of sand layers will be able to improve remarkably by construction of loaded filter on the top of the sand layer.

거골의 박리성 골연골염

하권익,한성호,양보규,김치홍,김태성 대한스포츠의학회 1995 대한스포츠의학회지 Vol.13 No.1

거골의 박리성 골연골염은 연골과 연골하골이 균열되고 관절 면으로부터 부분적 혹은 전체적으로 분리되는 병변으로 흔치 않은 병변이다. 거골의 박리성 골연골염은 잘 알려져 있음에도 불구하고, 수술적 치료의 결과에 대한 지식은 적은 편이다. 저자들은 1998년 1월부터 1992년 12월까지 만 5년간 16명, 16례의 거골 박리성 골연 골염 환자를 평균 29개월 추시관찰 및 분석하여 다음과 같은 결과를 얻었다. 1) 연령 분포는 최소 15세에서 최장 58세 였으며 평균 30세 였다. 2) 16명의 환자중 남자가 14례 여자가 2례였고 우측 거골이 10례, 좌측 거골이 6례 였다. 3) 외상과 관계있는 환자는 16례중 15례였으며 거골의 내측에 병변이 있는 경우가 10례, 외측이 6례 였으며 양측인 경우는 없었다. 4) 증상 발현후 수술까지의 기간은 최단 3개월에서 최장 7년이 였으며 평균 25.9개월 이었다. 16명 전례에서 동통을 호소하였으며 6명에서 강직 및 불안정성을 각각 호소하였다. 5) Berndt와 Harty에 의한 병변 분류는 stage Ⅰ은 없었으며 stage Ⅱ는 4례, stage Ⅲ가 7례, stage Ⅳ는 5례로 stage Ⅲ이 가장 많았다. 6) 치료는 관절 개방술에 의한 절제술(1례), 절제술과 소파술 및 다발성 천공술(8례), 절제술 및 소파술 (3례), 소파술 및 bone peg(1례), 관절경적 소파술 및 다발성 천공술 (3례) 시행하였으며 치료결과는 O'Farrell 등이 사용한 평가 방법에 의하면 우수 13례 (81%), 양호 2례(12.5%), 불량 1례 (6.5%)였다. Osteochondritis dissecans of the talus is defined as a subchondral bony lesion of small fragment of bone, usually under two centimetres in diameter, with overlying intact articular cartilage. This fragment then becomes separated from its bed and undergoes necrosis. Although the lesion of osteochondritis dissecans of the talus is well known, there is little information in the literature concerning the results of surgical treatment. Sixteen cases of osteochondritis dissecans of the talus, operated on between January 1988 and December 1992, were studied. All were available for follow-up an average 29 months later and clinical analysis were as follows; 1. Age incidence was distributed from 15 years to 58 years (average 28) 2. 16 patients (14 male, 2 female) were examined and followed-up ; in ten the right ankle was involved and six the left ankle. 3. Of the 16 patients, 14 patients were associated with a history of trauma and 10 patients had medial lesions and 6 patients, lateral lesions. 4. The duration of symptom on these cases ranged from 3 months to 7 years, with an average of 25.9 months. All patients complain of pain when using the ankle and 6 patients complain of stiffness of the ankle and sensation of Berndt and Harty, four ankles had a stage Ⅱ lesion, nine had a stage Ⅲ lesion and five had a stage Ⅳ lesion. 6. The methods of treatment were excision (1 case), excision, curettage and drilling (8 cases), excision and curettage (3 cases), curettage with bone pegging (1 case) and arthroscopic curettage and drilling (3 cases). According to O'Farrell grading system which combined subjective with the objective assessment, 13 patients (81%) had good results, 2 patients (12.5%) had fair results, and 1 patient (6.5%) had a poor result.

單結晶 실리콘의 異方性腐蝕에 관한 연구

權泰夏 釜山水産大學校 1984 釜山水産大學 硏究報告 Vol.24 No.1

1. 실리콘의 type에 관계없이 (100)面의 부식률은 PEW계 부식액에서는 110℃에서 약1㎛/min, 100℃에서 약0.8㎛/min 이었고, PN PW계 부식액에서는 85℃에서 약1㎛/min, 5℃에서 약0.8㎛/min이었다. 그리고 HW계 부식액에서는 100℃에서 약0.8㎛/min, 90℃에서 약0.55㎛/min이었다. 2. (111)面의 부식률은 數値로 나타내기는 어려우나, EPW계 부식액에서 기장 크고, 다음 HW계 PNPW계 부식액 順이었다. 3. (100)面에서 <100>방향으로 부식되어 가는 速度는 EPW계 부식액에서 가장 크고, HW계 PNPW계 부식액 順이었다. 4. 부식된 표면상태는 EPW계 부식액에 의해 부식된 경우는 균일하였고 다음이 PNPW계 부식액으로 부식시킨 겨우이며, 가장 나쁜 것이 HW계 부식액으로 부식시킨 것이었다. 압력 감지를 위해서 diaphragm을 만들 경우 EPW계 부식액을 사용하는 것이 가장 좋다는 것을 알 수 있었다. Anisotropic etching characteristics of single crystal silicon were investigated for the tvarious etching solutions. The etch rate of {100} plane is 1㎛/min in ethylenediamine-pyrocatechol-water (EPW) solutions, 0.8㎛/min in hydrazinehydrate-water(HW) solutions, and 1㎛/min in potassiumhydroxide-normalpropanol-water(PNPW) etchants. The etch rate {111} plane and the etching velocity in the <100> direction on the silicon wafer surfaces are the largest and etched surface conditions are the best in EPW etchants.

실리콘 압력검지소자의 제조 및 특성

권태하 釜山水産大學校 1985 釜山水産大學 硏究報告 Vol.25 No.1

1. 실리콘의 type에 관계없이 (100)면의 부식율은 EPW계 부식액에서는 110℃에서 약1㎛/min, 100℃에서는 약 0.8㎛/min이었고, KOH계 부식액에서는 85℃에서 약 1㎛/min, 75℃에서는 약 0.8㎛/min이었다. 그리고 HW계 부식에서는 100℃에서 약 0.8㎛/min, 90℃에서는 약 0.55㎛/min의 부식율을 나타냈다. 2. P-N접합부식정지법을 사용해서 두께가 10㎛ 및 20㎛인 두 종류의 다이아프램을 제작하였으며, 이때 인가한 전압은 약 0.4V였고 부식율은 2.35㎛/min 정도였다. 3. 다이아프램 위에서의 압력에 대한 저항변화는 변의 중앙에서 그변에 가깝게 위치한 저항에서 크게 나타났다. 4. 다이아프램의 두께가 10㎛인 압력센서의 압력감도는 42μV/V·㎜Hg 였으며, 다이아프램의 두께가 20㎛인 센서의 압력감도는 16μV/V·㎜Hg였다. 두 종류 모두 0∼300㎜Hg의 압력범위에서 좋은 직선상을 보였다. 5. 두께가 10㎛인 압력센서는 온도에 대해 96ppm/℃의 특성변화를 나타냈다. 이값은 2.3㎜Hg/℃에 대응된다. 6. 온도특성을 향상시키기 위한 온도보상회로의 부착과 소자를 부착하기 위한 적절한 지지판을 만들면 실용이 가능할 것으로 생각된다. The etch rates of silicon oriented (100) was investigated for three etching solutions. The 1×1㎟, 10㎛-thick silicon diaphragms have been made using the electrochemical P-N junction etch-stop technique. The 200Ω/square, 800Ω resistors were formed on the diaphragm and resistance was examined with pressure. Fractional resistance change depended on diaphragm thickness, resistor location, and resistor length etc. The 1.2㏀ full bridge resistors produced a pressure sensitivity of 42㎶/Ⅴ·㎜Hg with a temperature coefficient of 2.3㎜Hg/℃ and showed a good linearity from 0 to 300㎜Hg pressure range.

마이크로프로세서를 利用한 溫度制御

權泰夏,鄭信一,禹鐘鎬 釜山水産大學校 1982 釜山水産大學 硏究報告 Vol.22 No.2

本 論文에서는 마이크로프로세서와 溫度符號化器를 利用해서 溫度를 計數的으로 制御할 수 있는 시스템을 보다 간단히 構成하였으며 上昇기울기, 維持溫度, 降下기울기에 따라 多少의 差는 있으나 制御溫度의 變化幅이 ±0.3% 以內로 比較的 良好하게 制御되었다. bit數가 많은 A/D 變換器를 使用한다면 보다 더 精密한 溫度制御가 可能할 것이다. 現在狀態로도 實驗室의 小容量 뿐 만 아니라 産業用의 大容量 電氣爐의 溫度制御에도 利用될 수 있을 것으로 본다. This paper describes the temperature control system of an electric furnace using a SDK-85 microprocessor system as a control unit. The hardware structure of the control system was very simplified by eliminating mechanical drive portions and employing electronic circuits instead. Moreover, by employing a software method in the system desired temperature on time, i.e., rising rate, maintaining temperature and time, falling rate, can be easily controlled and changed by program. Experimental results showed the successful operation with flexibility. Temperature variation was less than ±0.3% of the desired value and was more accurate on the maintaining temperature region.

분말사출성형을 통해 제조된 17-4 PH STS의 인장특성에 미치는 초기 충진율과 열린 기공의 영향

하태권,성환진 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-

Powder injection molding (PIM) makes use of the shaping advantage of injection molding and is applicable to metals and ceramics. PIM delivers structural materials in a shaping technology, previously restricted to polymers. In this study, the 17-4 PH stainless steel powders with average diameters of 6-14 μm were injection-molded into flat tensile specimens. Sintering of the compacts was carried out at the various temperatures ranging from 1350oC for Ih. In the case of the compacts made with 10-μm powder, sintering temperature was taken from 200-1350oC to investigate the effect of relative density on the tensile properties.

실내사무환경의 환경성담배연기(ETS)의 지표물질에 관한 연구

하권철,백남원,박동욱,윤충식,김원,최상준,박지영,최인자,김신범,강태선 한국산업위생학회 2003 한국산업보건학회지 Vol.13 No.2

The purpose of this research is to evaluate indoor office environment using the concentrations of nicotine, 3-enthenyl-pyridine(3-EP), and respirable suspended particulate(RSP), which are indicators for environmental tobacco smoke(ETS) and the correlations between indicators and environmental conditions(smoking density, smoking index). The mean air charge per hour (ACH) in smoking rooms was 10.4 and most of the smoking rooms showed non-compliance withe ASHRAE standard value except only one smoking rooms. The concentrations of RSP, 3-EP, nicotine showed log=normal distributions, and became different statistically depending on smoking condition(p〈0.01). The geometric mean concentration of RSP in smoking room was 441.7 ug/㎡ that is far exceeded environmental standard(150 ug/㎡). This implies that fine particulate in smoking room should be carefully controlled considering smoking density and ventilation fate. The mean concentrations of nicotine and 3-EP were 93.4 ug/㎥, respectively. The correlation coefficients between RSP and SI, 3-EP and SI, and Nicotine and SI were 0.67, 0.84 and 0.74, respectively. The correlation coefficient between nicotine and 3-EP, nicotine and RSP, and RSP and 3-EP were 0.76,0.78 and 0.57 respectively.