견실성 향상을 위한 직류서어보모터의 가속도제어

장기효,홍창희 한국통신학회 1990 韓國通信學會論文誌 Vol.15 No.3

직류 서어보 모터는 속도 및 위치제어계에서 성능이 뛰어나므로 위치제어계로 많이 사용하고 있지만 불확실한 외란이나 부하 Torque 변동들이 직류서어보 모터의 위치제어계에서 발생할 때 정상상태 혹은 과도상태 오차가 발생한다. 본 논문에서는 이 오차를 가속도 제어법을 통해서 감소시키는 견실성이 높은 제어법을 제안하고 컴퓨터 시뮤레이션을 통해서 가속도 제어기법의 유효성을 확인하였다. DC servo motor has been often used as the position control system, because the performance is excellent on the velocity and position control system. When the unknow disturbance and accessible load torque are imposed on the position control of DC servo motor, this system has the steady and/or transient state error. In this paper, a new method which has high stiffness for reducing the error is proposed. This error will be reduced by acceleration control. The effectiveness of the acceleration control is confirmed by using computer simulation.

Model 추종형 Servo Controller에 의한 위치제어계의 설계

장기효,하홍곤,홍창희 한국통신학회 1991 韓國通信學會論文誌 Vol.16 No.1

In this paper the design and construction of discrete model following servo dontroller on the position control system is proposed. The operational time delay of the plant in the controller which is proposed, is considered and the system which is added by the integral compensation in first order difference equation is constructed. By applying the optimal regulator method to the system, the method which find the optimal state feedback gain is developed theoretically. The output of a model which is correspond to a DC Servo motor follow quickly the speed response of a DC Servo motor and the velocity error in ansteady-state is reduced in zero and the position response is controlled correctly, the performance of the controller is contoller is confirmed by Computer Simulation.

Model Following Control System을 이용한 퍼지 적응制御

장기효,박재호 동의공업대학 2001 論文集 Vol.27 No.1

An adaptive fuzzy control with using Model Following Control system is proposed, in this paper, which can compensate disturbances in much shorter than model reference adaptive control system. A discrete DC servomotor control system is designed as the model following control system. In addition, adaptive fuzzy system is included for compensation of disturbances. Adaptive fuzzy control system equipped with a training algorithm, where the fuzzy logic system is constructed from a collection of fuzzy IF-THEN rules, and the training algorithm adjusts the parameter of fuzzy system based on numerical input-output pairs. The Adaptive fuzzy control is then to find a method of adjusting the fuzzy rule-base parameter for the controller when the characteristics of the process and its parameter changing unpredictably. The performance of the proposed control system is analyzed by computer simulation for model and plant. Excellent agreements have been the results and theorical ones.

Effects of Dietary Fructan on Cecal Enzyme Activities in Rats

장기효,Soon Ah Kang,Uckhan Chun 한국생물공학회 2005 Biotechnology and Bioprocess Engineering Vol.10 No.6

In this study, we have attempted to determine the effects of dietary fructose polymers (fructan), high molecular-weight β-(2,6)-linked levan, and low-molecular-weight β-(2,1)-linked inulin, on two intestinal enzymes (β-glucuronidase and β-glucosidase). As a preliminary experiment, when intestinal microflora were cultured in anaerobic media harboring levan or its oligosaccharides, bacterial cell growth was observed in the levanoligosaccharide-supplemented media, but not in the levan-supplemented media, indicating that levan’s size is important for the utilization by intestinal bacteria of levan as an energy source. In our animal study, the intake of a levan-rich diet was determined to significantly attenuate the activity of the harmful enzyme β-glucuronidase, but did not affect the activity of β-glucosidase.

건조 담체 고정화 Zymomonas mobilis 세포의 oxidoreductase 활성도

장기효,이제혁,전억한 경희대학교 유전공학연구소 1991 遺傳工學論文集 Vol.3 No.-

박테리아인 Zymomonas mobilis는 glucose와 fructose를 각각 gluconic acid와 sorbitol으로 동시전환할 수 있다. Glucose fructose oxidoreductase에 의하여 glucose의 산화와 fructose의 환원이 일어난다. 균체를 cationic detergent인 CATB(cethyltrimethylammoniumbromide)로 처리하여서 투과성을 높인 후에 glutaraldehyde로 crosslinking 하였던 결과, 균체에서의 glucose-fructose oxidoreduc-tase의 유출이 감소되었으며 고정화균체의 안정성이 증가하였다. 투과성을 증가시킨 균체를 K-carra-geenan으로 고정화하여서 연속공정을 실시한 결과 효소의 안정성이 30일 이상 지속되었다. Kcarrageenan으로 고정화한 균체를 건조시 beads의 견고성과 저장성의 향상이 나타났다. 건조된 Kcarrageenan 담체의 V_(max)값은 39C와 pH6.2에서 free cells의 거의 절반값을 나타내었다. 연속공정에서 회석비율 0.1h^(-1)일때 wet beads와 건조 beads에서의 sorbitol 생산성은 각각 3.2∼3.5, 2.85∼2.9(g/l-h)를 나타내었다. The bacterium Zymumonas mobilis is able to convert glucose and fructose to gluconic acid and sorbitol simultaneously. The enzyme complex, which is responsible for glucose oxidation and fructose reduction, has been described as glucose-fructose oxidoreductase. After treatment of the cells with cationic detergent CTAB(Cetyltrimethylammoniumbromide) for permeabilization, the cells were treated with glutaraldehyde in order to crosslink enzymes. Glutaraldehyde treatment of the permeabilized cells could improve the stability of the system by decreasing the loss of glucose-fructose oxidoreductase. The methods of glutaraldehyde cross-linking of enzymes in CTAB treated cells immobilized in K-carrageenan showed a stable ability of enzymes in CTAB treated cells oxidoreductase for 30 days of process. K-carrageenan beads entrapped with permeabilized cells were dried to improve bead rigidity and storage stability. The value of V_(max) for the dry K-carrageenan beads was found to a 1/2 of that of free cells. It was shown that the productivities of the continuous process with wet K-carrageenan beads and dry beads at dilution rate 0.1h^(-1) were 3.2-3.5 g/l-h and 2.85-2.9 g/l-h, respectively.

건조 고정화 Zymomonas mobilis에 의한 sorbitol 생산

장기효,박철진,전억한 慶熙大學校 大學院 院友會 1992 高凰論集 Vol.11 No.-

The purpose of this study is to develop a continuous process for sorbitol production using dried Zymomonas mobilis immobilized in K-carrageenan. The methods of glutaraldehyde cross-linking of enzymes in CTAB(cetyltrimetylammoniumbromide) treated cells immobilized in K-carrageenan showed a stability for the production of sorbitol for 30 days of operation K-carrageenan beads entrapping permeabilized cells were dried to improve bead rigidity and storage stability. A semi-batch process with dry beads was carried out and only a small loss of enzyme activity(less than 8%) was observed during 72h. The value of Vmax for the dry K-carrageenan beads was found to be one half of that for free cells. It was shown that the productivities of the continuous process with wet K-carrageenan beads and dry beads at a dilution rate 0.1h^-1 were 3.4g/L and 2.88g/L-h respectively.

Model 追從 制御系를 이용한 堅實한 Fuzzy 制御

장기효,박재호 동의공업대학 1999 論文集 Vol.25 No.1

Robust control has been the purview of quantitative linear control techniques for a long time, while qualitative, symbolic control has been deemed to be more suitable to obtaining complex control objectives that require only low output precision. Since the dynamic response trajectory of a traditional fuzzy controller can not be quantitatively controlled, a Robust fuzzy control with model following controller is proposed in this paper. In the proposed controller, an output feedback linear model following control is designed first according to the roughly estimated plant model to let its response follow the out put generated by a reference model. Then a model following error driven control signal is synthesized such that good model following characteristics can be preserved at various operation conditions. The proposed controller is applied to the speed control of a servomotor. Dynamic signal analysis of model following behavior is made and the procedure for constructing the control algorithms is described detailedly. The performance of the drive and the effectiveness of the proposed controller are demonstrated by some simulation results.

A mixture of poly-γ-glutamic acid and levan ameliorates obesity in high fat diet-induced mice

장기효,김미자 한국식품과학회 2022 Food Science and Biotechnology Vol.31 No.3

Anti-obesity effects of a mixture of poly-c-glu- tamic acid (c-PGA) and levan (PL, 6:4 w/w) were evalu- ated using C57BL/6 mouse models including normal diet (G1), normal diet containing 5% of PL (G2), high-fat diet (HFD) (G3), HFD with 3% of PL (G4), and HFD with 5% of PL (G5) and followed by breeding 12 weeks. After 12 weeks, the content of epididymal fat and the size of fat cell for test animals were significantly decreased by com- paring G3 (p \ 0.05). Similarily, contents of serum triglyceride, total cholesterol, LDL cholesterol, insulin and leptin in G5 were significantly decreased than G3. Fat accumulations and inflammatory degrees within liver and fat cells were also decreased in the G5 than G3. In addition 5% PL diet might not have any problems causing liver damages. Conclusively, a mixture of c-PGA and levan could help to improve obesity and dyslipidemia due to high-fat meals.

잣송이 추출물의 이화학적 특성 및 항산화 활성

장기효(Ki-Hyo Jang),서정희(Jeonghee Surh) 한국식품영양과학회 2017 한국식품영양과학회지 Vol.46 No.1

본 연구에서는 식품으로 활용하기 위해 제조된 잣송이 추출물의 이화학적 품질 특성과 항산화 활성을 탐색하였다. 잣송이 추출물은 수분과 탄수화물이 구성성분 대부분을 차지하고 있었으며, 특히 대조군으로 사용된 매실 추출물보다 수분함량은 낮고 당 함량은 높아 유의적으로 높은 점도를 나타내었다. 또한, 갈색도와 색도는 모두 낮아 매실 추출물과 비교해 숙성 중 Maillard 갈변 반응의 정도가 상대적으로 낮았음을 시사해주었다. 잣송이 추출물은 매실 추출물보다 플라보노이드 함량은 유의적으로 다르지 않았으나 유기산 함량과 갈변도는 1/10 수준으로 유의적으로 낮았고, 총환원력은 매실 추출물의 60% 수준으로 측정되었다. 그런데도 잣송이 추출물에서 매실 추출물과 유사한 높은 금속 소거능과 라디칼 소거 활성이 관찰되었다. 또한, 잣송이 추출물 속 플라보노이드 총량보다도 많은 양인 6.6 mM quercetin과 비교할 때 2배나 높은 SOD 유사 활성을 나타내었다. 이는 잣송이 추출물에 quercetin보다 항산화 활성이 높은 플라보노이드가 존재할 가능성을 보여주며, 플라보노이드 조성에 대한 후속연구의 필요성을 시사해주었다. 본 연구는 잣송이 추출물이 제조법과 용도가 유사한 매실 추출물에 버금가는 항산화 활성을 부여하면서도 상대적으로 높은 당 함량과 낮은 유기산 함량으로 매실 추출물과는 관능적 측면에서 차별화 될 수 있는 식품으로서의 활용 가능성을 보여주었다. Pinus koraiensis cone (PKC) extract was prepared by mixing PKC with sugar at a weight ratio of 1:1 and then removing PKC after incubating the mixture at room temperature for 100 days. The resulting PKC extract was examined for its physicochemical properties and antioxidant activities using Prunus mume fruit extract, which is similar to PKC extract in terms of preparation procedure and product usage, as a control. PKC extract consisted mainly of moisture (21.76%) and sugar (70.03%), leading to high viscosity. PKC extract was apparently yellowish, and therefore its browning index and color intensity were appreciably lower than the control (P=0.0000), indicating that Maillard reaction was not facilitated during fermentation. Compared with the control, PKC extract was not appreciably different in terms of total flavonoid content, whereas its organic acid content and total reducing capacity were significantly lower. Nevertheless, its metal-chelating activity and DPPH radical scavenging activity were comparable to those of the control. In addition, SOD-like activity of PKC extract was 2-fold higher than that of 6.6 mM quercetin, which had a higher total flavonoid content than PKC extract. This indicates that PKC extract contains certain flavonoids with higher antioxidant activities than quercetin. The results show that PKC extract provides antioxidant activity as well as characteristically different sensory properties due to its higher sugar and lower organic acid contents compared with Prunus mume fruit extract.

식이 레반과 이눌린이 흰쥐의 장내 유산균 성장 및 장내환경에 미치는 영향

장기효(Jang Ki Hyo),강순아(Kang Soon Ah),조윤희(Cho Yunhi),김윤영(Kim Yun Young),이윤정(Lee Yun Jung),홍경희(Hong Kyunghee),장은경(Jang Eun-Kyung),김철호(Kim Chul Ho),조여원(Choue Ryowon) 韓國營養學會 2002 Journal of Nutrition and Health Vol.35 No.9