• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.31-37
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• 2003

A robust tracking control for nonholonomic dynamic systems is proposed in this paper. Since nonholonomic dynamic systems have constraints imposed on motions that are not integrable, i.e., the constraints cannot be written as time derivatives of some functions of generalized coordinates, advanced techniques are needed for their control. It is shown that if the state of nonholonomic systems is mapped into a bounded space by a coordinate transformation, a robust controller for dynamic models of nonholonomic systems with input disturbances can be designed using sliding mode control. Stability and robustness of the proposed controller are proved in the Lyapunov sense. Numerical simulations on the trajectory tracking of a two-wheeled mobile robot are conducted to validate the effectiveness of the proposed controller.

• 전자공학회논문지B
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• 제29B권10호
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• pp.37-45
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• 1992

For a precise manipulator control in the presence of environmental uncertainties, it has long been recognized that the robot should be controlled in a task-referenced space. In this respect, an effective visual servo control system for robot manipulators based on neural networks is proposed. In the proposed control system, a Backpropagation neural network is used first to learn the mapping relationship between the robot's joint space and the video image space. However, in the real control loop, this network is not used in itself, but its first and second derivatives are used to generate servo commands for the robot. Second, and Adaline neural network is used to identify the approximately linear dynamics of the robot and also to generate the proper joint torque commands. Computer simulation has been performed demonstrating the proposed method's superior performance. Futrhermore, the proposed scheme can be effectively utilized in a robot skill acquisition system where the robot can be taught by watching a human behavioral task.

• 전기학회논문지
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• 제58권9호
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• pp.1821-1826
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• 2009

An adaptive neural controller for perturbed strict-feedback nonlinear system is proposed. All the previous adaptive neural (or fuzzy) controllers are based on the backstepping scheme where the universal approximators are employed in every design steps. These schemes involve virtual controls and their time derivatives that make the stability analysis and implementation of the controller very complex. This fact is called 'explosion of complexty ' since the complexity grows exponentially as the system dynamic order increases. The proposed adaptive neural control scheme adopt the backstepping design procedure only for determining ideal control law and employ only one neural network to approximate the finally selected ideal controller, which makes the controller design procedure and stability analysis considerably simple compared to the previously proposed controllers. It is shown that all the time-varing signals containing tracking error are stable in the Lyapunov viewpoint.

• 생명과학회지
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• 제33권2호
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• pp.169-175
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• 2023

자외선으로 야기되는 피부조직의 손상에 대한 방어기전으로 멜라닌세포는 멜라닌 색소를 생산한다. 이러한 멜라닌 생성에는 tyrosinase 효소가 중추적인 역할을 수행한다. 그러나 과다한 멜라닌 생성은 피부조직에 주근깨와 검버섯 등의 과다 색소침착 병변을 일으킨다. 따라서 tyrosinase 발현이나 활성을 조절함으로써, 과도한 멜라닌 생성을 억제하는 물질을 발굴하는 것은 임상적인 의미가 있다. Catechin은 tyrosinase 발현을 저해함으로써 멜라닌 생성을 억제하는 화합물로 알려져 있다. 본 연구에서는 B16F10 마우스 흑색종 세포주와 버섯에서 추출된 tyrosinase를 사용하여, 참느릅나무의 줄기 껍질에서 추출 및 동정된 catechin 유도체 화합물(C5A, C7A, C7G, 및 C7X)의 멜라닌 생성 억제 효능을 검증하였다. 먼저, B16F10 세포주에서, 세포독성을 나타내지 않는 농도의 catechin 유도체 화합물 처리는, 모두α-MSH로 촉진된 멜라닌 생합성을 억제하는 효능을 보였다. Catechin 유도체 화합물의 이러한 효능은 멜라닌 생합성 저해제로 잘 알려진 kojic acid와 비슷한 수준이였다. 또한, C5A와 C7A는 버섯에서 추출된 tyrosinase의 효소 활성을 통계적으로 유의하게 억제하였다. 또한, 컴퓨터 분석을 통해 C5A와 C7A는 kojic acid와 유사한 수준으로 tyrosinase의 active site에 결합할 것으로 예측되었다. 이에 더하여, 4종류의 catechin 유도체 화합물 모두가 α-MSH 처리된 B16F10 세포주에서 tyrosinase 단백질 발현을 감소시켰다. 본 연구결과를 종합하면, 참느릅나무에서 추출/동정된 catechin 유도체 화합물은 멜라닌세포의 멜라닌 생성을 효과적으로 억제하였다. 따라서, 본 연구결과는 이러한 catechin 유도체 화합물이 피부의 과다 색소침착 질환 제어를 위한 새로운 조절 물질로 응용될 수 있음을 제시한다.

• 대한기계학회논문집
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• 제18권6호
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• pp.1399-1411
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• 1994

A model helicopter has more versatile flight capability than the fixed-wing aircraft and it can be used as an unmaned vehicle in hazardous area. A helicopter, similar to other aircrafts, is an unstable, multi-input multi-output nonlinear system exposed to strong disturbance. So it should be controlled by robust control theories that can be applied to multivariable systems. In this study, motion equations of hovering are established, linearized and transformed into a state equation form. Various parameters are measured and calculated in other to obtain the stability derivatives in the state equation. Hovering flight controller is designed using the digital LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) control theory. The designed controller is tested by the nonlinear simulations and implemented on an IBM-PC/386. Experiments were carried out on a model helicopter attached to the 3-DOF gimbal. The designed controller showed satisfactory hovering capability to maintain the hovering for more than 40 seconds.

• 한국잡초학회지
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• 제13권2호
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• pp.89-95
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• 1993

광합성 전자전달저해제의 탐색을 위한 biorational screening 방법으로 광합성 박테리아의 일종인 cyanobacteria의 표준형(wild type)과 $D_1$ 단백질의 구성 아미노산이 변환된 변이주 Di-1, G-264. Di-22 등 4종을 사용하여 신규합성 화합물에 대한 광합성 전자전달저해활성을 조사하여 구조-활성간의 특성을 검토하였고, 이들의 thermoluminescence band를 이용하여 결합부위를 비교하였다. 1. Phenol 화합물(E-series)들은 cyanobacteria를 이용한 광합성 전자전달 저해활성의 양상을 볼 때 diuron보다는 dinoseb과 비슷하였다. 2. 합성한 Phenol화합물에서 나타난 구조활성간의 특정으로는 치환기의 phenyl ring에 C1이 치환되지 않은 경우 Hill반응 저해활성이 나타나지 않았고, 화합물에 있는 두개의 ring을 연결하는 bridge의 길이가 길어질수록 Hill반응 저해활성은 약하게 나타났다. 3. Triazine 화합물(T-series)의 경우 T-27, T-28화합물은 대조약제 atrazine보다 각각 10, 30배 강한 저해활성을 나타내었고, 변이주 G-264에 대 한 저항성 비율이 atrazine보다 더욱 크게 나타나 이들 화합물들의 결합부위가 $D_1$ 단백질의 264번 위치와 깊은 관계가 있을 것으로 생각되었다. 4. Triazine 화합물에 있어서 치환기 -C-NH-는 전자전달계에 중요한 작용기로 생각되었다. 5. Thermoluninescence band를 이용하여 결합부위를 비교할 수는 있었지만, 명료하게 구분되지 않았다.

• 제어로봇시스템학회논문지
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• 제10권2호
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• pp.112-124
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• 2004

A neural network based adaptive reconfigurable flight controller is presented for a class of discrete-time nonlinear flight systems in the presence of variations of aerodynamic coefficients and control effectiveness decrease caused by control surface damage. The proposed adaptive nonlinear controller is developed making use of the backstepping technique for the angle of attack, sideslip angle, and bank angle command following without two time separation assumption. Feedforward multilayer neural networks are implemented to guarantee reconfigurability for control surface damage as well as robustness to the aerodynamic uncertainties. The main feature of the proposed controller is that the adaptive controller is developed under the assumption that all of the nonlinear functions of the discrete-time flight system are not known accurately, whereas most previous works on flight system applications even in continuous time assume that only the nonlinear functions of fast dynamics are unknown. Neural networks learn through the recursive weight update rules that are derived from the discrete-time version of Lyapunov control theory. The boundness of the error states and neural networks weight estimation errors is also investigated by the discrete-time Lyapunov derivatives analysis. To show the effectiveness of the proposed control law, the approach is i]lustrated by applying to the nonlinear dynamic model of the high performance aircraft.

• Journal of Chest Surgery
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• 제38권9호
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• pp.595-600
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• 2005

배경: 콜키신(Colchicine)은 면역 억제 작용을 갖고 있어 자가 면역 질환인 통풍(Gout)등의 질환의 치료제로 이용되어 왔다. 본 연구는 콜키신을 동종이형의 심장이식된 백서에 투여하여 면역억제효과를 확인하고자 하였다. 대상 및 방법: 백서에서의 동종이형 심장이식 거부 반응에 대하여 면역억제제를 투여하지 않는 대조군(Control group)(n=6)과 사이클로스포린(Cyclosporin A) 투여군(n=20), 콜키신 변형물질 투여군(n=20)을 비교함으로써 콜키신의 면역 억제 효과를 비교 검토하였다. 결과: 면역억제제를 투여하지 않은 대조군(n=6)에서는 모두 3주 이내에 거부반응을 보였고, 사이클로스포린(Cyclosporin A) 투여군(n=20)에서는 감염으로 추정되는 한 마리가 술 후 18일째 죽었고, 나머지 19마리는 100일 이상 생존하였다. 또한 콜키신 변형물질 투여군(n=20)에서도 술 후 9일 째에 마취 문제로 인한 호흡부전으로 한 마리가 사망한 외에 나머지는 100일 이상 생존하였다. 결론:본 실험에서는 백서에서의 동종이형 심장 이식 후 현재 면역억제제로 널리 사용되고 있는 Cyclosporin A 투여군과 콜키신 변형물질 투여군을 비교하여 본 바 콜키신 변형 물질 투여군에서도 Cyclosporin A 투여군과 마찬가지로 장기 생존의 결과를 얻을 수 있어 면역 억제 효과가 있음을 알 수 있었다.

• Parasites, Hosts and Diseases
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• 제52권6호
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• pp.631-637
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• 2014

Genetic characteristics of Plasmodium falciparum may play a role in the treatment outcome of malaria infection. We have studied the association between diversity at the merozoite surface protein-1 (msp-1), msp-2, and glutamate-rich protein (glurp) loci and the treatment outcome of uncomplicated falciparum malaria patients along the Thai-Myanmar border who were treated with artemisinin derivatives combination therapy. P. falciparum isolates were collected prior to treatment from 3 groups of patients; 50 cases of treatment failures, 50 recrudescences, and 56 successful treatments. Genotyping of the 3 polymorphic markers was analyzed by nested PCR. The distribution of msp-1 alleles was significantly different among the 3 groups of patients but not the msp-2 and glurp alleles. The allelic frequencies of K1 and MAD20 alleles of msp1 gene were higher while RO33 allele was significantly lower in the successful treatment group. Treatment failure samples had a higher median number of alleles as compared to the successful treatment group. Specific genotypes of msp-1, msp-2, and glurp were significantly associated with the treatment outcomes. Three allelic size variants were significantly higher among the isolates from the treatment failure groups, i.e., $K1_{270-290}$, $3D7_{610-630}$, $G_{650-690}$, while 2 variants, $K1_{150-170}$, and $3D7_{670-690}$ were significantly lower. In conclusion, the present study reports the differences in multiplicity of infection and distribution of specific alleles of msp-1, msp-2, and glurp genes in P. falciparum isolates obtained from treatment failure and successful treatment patients following artemisinin derivatives combination therapy.

• Asian-Australasian Journal of Animal Sciences
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• 제19권6호
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• pp.857-864
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• 2006

The aim of this study was to apply the Cornell net carbohydrate and protein system (CNCPS) in subtropical Taiwan. This was done by means of 3 trials, viz, in situ, lactation and metabolic trials, the latter using the urinary purine derivatives (UPD) to estimate the ruminal microbial yield. Dietary treatments were formulated according to different nutrient requirement systems including, (1) a control NRC78 group on NRC (1978), (2) a NRC88 group on NRC (1988), and (3) a CNCPS group on Cornell Net carbohydrate and protein system model. Results from the lactation trial showed that DM intake (DMI) was higher (p<0.05) in the NRC78 than the other treatment groups. The treatments did not significantly influence milk yield, but milk yield after covariance adjustment for DMI was higher in the CNCPS group (p<0.05). The FCM, milk fat content and yield were greater in both the NRC78 and the NRC88 group over the CNCPS group (p<0.05). The treatments did not significantly influence the DMI adjusted FCM. The solid-non-fat and milk protein contents were higher in the CNCPS group (p<0.05) with or without DMI covariance adjustment. Lactating efficiency was higher in the CNCPS group (p<0.05) compared to the other groups. The significantly lowest milk urea-N (MUN) with better protein utilization efficiency in the CNCPS group (p<0.05) suggested that less N would be excreted into the environment. Cows in the CNCPS group excreted significantly more and the NRC88 group significantly less urinary purine derivatives (UPD) implying that more ruminal microbial protein was synthesized in the CNCPS over the NRC88 group. The CNCPS could become the most useful tool in predicting the trends in milk yield, microbial yield and MUN.