• 전기학회논문지
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• 제61권11호
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• pp.1606-1610
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• 2012

Hysteresis current regulator has been used widely because of its simple principle and structure. However, when the current band width is too narrow or the applied voltage is relatively too high, the switching frequency may increase abruptly and it generates a large amount of heat. Thus, this study will suggest a better and simple method to reduce the switching frequency. For single phase current control, the proposed hysteresis current control is executed by adding 0 mode state and comparing the slope of the current reference. This simple method decreases the generated switching frequency and significantly reduces the generated heat. This proposed method was proved with simulations and experiments comparing with the classical hysteresis current control method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.542-544
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• 2006

This paper aims to provide a way to improve dynamic stability of biped robots against undesirable disturbances and in a slope. By using an angular velocity sensor and an acceleration sensor on its waist, we can make a medium-sized biped robot walk stably in a slope against impulsive disturbances. In addition, it is possible for the robot to walk stably in an unknown slope. The measured signals from the sensor are used for compensating the reference angles of ankle, knee, and pelvis joints. Some experiments show that the stability of the robot is much enhanced by using cheat sensors and a simple algorithm. This work helps bided robots walk more stably in real environments.

• 대한전자공학회논문지
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• 제26권11호
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• pp.1666-1671
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• 1989

A novel switched-capacitor circuit for interfacing capacitive microtransducers with a digital system is developed based on the dual-slope integration. It consists of a differential integrator and a comparator. Driven by the teo phase clock, the circuit first senses the capacitance difference between the transducer and the reference capacitor in the form of charge, and accumulates it into the feedback capabitor of the integrator for a fixed period of time. The resulant accumulated charge is next extracted by the known reference charge until the integrator output voltage refurns to zero. The length of time required for the integrator output to return to zero, as measured by the number of clock cycle gated into a counter is proportional to the capacitance difference, averaged over the integration period. The whole operation is insensitive to the reference voltage and the capacitor values involved in the circuit, Thus the proposed circuit permits an accurate differental capacitance measurement. An error analysis has showh that the resolution as high as 8 bits can be expected by realizing the circuit in a monolithic MOS IC form. Besides the accuracy, it features the small device count integrable onto a small chip area. The circuit is thus particularly suitadble for the on-chip interface.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권6호
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• pp.413-420
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• 2012

Purpose: The purpose of this setback genioplasty study is to develop a prediction method for the calculated osteotomy angle using horizontal and vertical changes as well as to evaluate the proportion of hard and soft tissue changes. Methods: Twelve patients who had received setback genioplasty with other maxillofacial surgery were examined. Three lateral cephalograms were taken just before surgery, immediately after surgery, and 3 months later surgery. A reference line was established to the reference point of the inner most point of the lingual symphysis cortex, incisor tip, and 2nd molar cusp tip. Measuring was conducted from pogonion (Pg), menton (Me), labrale inferius (Li), Mentolabial fold, soft tissue pogonion (Pg'), and soft tissue menton (Me') to the reference lines. Results: In setback genioplasty, the skeletal Pg moved posteriorly 5.07 mm. The ratios of soft tissue to hard tissue movement were 36% posteriorly and 62% inferiorly at Pg', 67% posteriorly and 104% inferiorly at Me', and 34% anteriorly and 164% posteriorly at Li. In reduction & setback genioplasty, skeletal Pg moved posteriorly 4.63 mm and skeletal Me moved superiorly 3.63 mm. The ratios of soft tissue to hard tissue movement were 76% posteriorly and 18% superiorly at Pg', 68% posteriorly and 42% superiorly at Me', and 44% anteriorly, 124% posteriorly at Li. The calculated mean slope angle, based on ${\Delta}H/{\Delta}V$ ratio, was 61.25 and the measured mean slope angle was 60.17. Thus, the calculated and measured slope angles have a similarity. Conclusion: In setback genioplasty, soft tissue moves posteriorly and inferiorly. In particular, at the Me' and Pg', the inferior movement of the soft tissue is greater than the posterior movement. Also, the predictable results (measured slope angle) after operation can be achieved by the calculated slope angle. Thus, the relationship of soft and hard tissue changes must be considered as the results are predictable.

• 한국운동역학회지
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• 제27권4호
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• pp.269-278
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• 2017

Objective: The purpose of this study was to develop a goal setting method for increasing the probability of a holed in a side inclined putting stroke. Method: Three-dimensional video data was recorded at a frequency of 120 hz per second after synchronizing 19 infrared motion capture systems (Qualisys, Gothenburg, Sweden). Putting green used a polycarbonate plate ($1.2{\times}2.4{\times}0.01meter$) with coefficient of friction (${\mu}=0.062$) and a real curve of the actual hole. Results: The velocity ratio between the club and the ball was 1:1.6 under various ball speed conditions in this study. The overall position of the break is 1 m to 1.4 m from the point where the ball leaves. If there is a slope, the ball follows the target line by the straightening force, and when it reaches 1 m position, the straightening force decreases by 30~50% and reaches to the deviation (break) point which is severely influenced by the slope. From here, the ball is aimed in a direction other than the target, and the size is affected by the slope. Conclusion: If there is a side slope, the ball moves away from the straight line, and the larger the slope, the closer the break point is to the starting point of the ball. Therefore, it is necessary to calculate the degree of departure according to the slope carefully, and it is preferable that the slower the speed is, the more the influence of the slope becomes. It is preferable to use the center of the hole as a reference when calculating the departure.

• Geomechanics and Engineering
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• 제18권4호
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• pp.353-362
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• 2019

Soil-rock mixture (S-RM) is an inhomogeneous geomaterial that is widely encountered in nature. The mechanical and physical properties of S-RM are important factors contributing towards different deformation characteristics and unstable modes of the talus slope. In this paper, the equivalent substitution method was employed for the preparation of S-RM test samples, and large-scale triaxial laboratory tests were conducted to investigate their mechanical parameters by varying the water content and confining pressure. Additionally, a simplified geological model based on the finite element method was established to compare the stability of talus slopes with different strength parameters and in different excavation and support processes. The results showed that the S-RM samples exhibit slight strain softening and strain hardening under low and high water content, respectively. The water content of S-RM also had an effect on decreasing strength parameters, with the decrease in magnitude of the cohesive force and internal friction angle being mainly influenced by the low and high water content, respectively. The stability of talus slope decreased with a decrease in the cohesion force and internal friction angle, thereby creating a new shallow slip surface. Since the excavation of toe of the slope for road construction can easily cause a landslide, anti-slide piles can be used to effectively improve the slope stability, especially for shallow excavations. But the efficacy of anti-slide piles gradually decreases with increasing water content. This paper can act as a reference for the selection of strength parameters of S-RM and provide an analysis of the instability of the talus slope.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.504-507
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• 2006

Airborn Lidar technology has been applied to diverse applications with the advantages of accurate 3D information. Further, Lidar intensity, backscattered signal power, can provid us additional information regarding target's characteristics. Lidar intensity varies by the target reflectance, moisture condition, range, and viewing geometry. This study purposes to generate normalized airborne LiDAR intensity image considering those influential factors such as reflectance, range and geometric/topographic factors (scan angle, ground height, aspect, slope, local incidence angle: LIA). Laser points from one flight line were extracted to simplify the geometric conditions. Laser intensities of sample plots, selected by using a set of reference data and ground survey, werethen statistically analyzed with independent variables. Target reflectance, range between sensor and target, and surface slope were main factors to influence the laser intensity. Intensity of laser points was initially normalized by removing range effect only. However, microsite topographic factor, such as slope angle, was not normalized due to difficulty of automatic calculation.

• 농촌계획
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• 제8권3호
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• pp.15-23
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• 2002

The study was performed to establish a criteria which can be served as a reference in preparing upland direct payment program in Korea, by analyzing WTO agreement content and by studying about direct payment program in EU and Japan and by slope analysis using GIS. Slope analysis using GIS was operated by 1/5000 digital map, and a field survey was put in practice, and merits and demerits were deduced. We can propose a criteria to select the disadvantaged areas in aspects of physical condition, farming condition. and economical and social condition is important to regionally classify "less-favored area(LFA)" and LFA division by economical and social condition is needed to identify legally. Therefore, we would propose a criteria which can select "less-favored area" by analyzing WTO agreement content and by studying about direct payment program in EU and Japan and slope analysis using GIS and a field survey.

• 전력전자학회논문지
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• 제14권2호
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• pp.112-119
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• 2009

본 논문은 홀센서를 사용하는 고속 소형 BLDCM의 속도제어를 위해 PLL 방식을 적용하였다. 제안된 방식은 기준펄스 신호와 홀센서 신호와의 위상차를 이용하는 PLL 기반의 속도제어 기법으로, 별도의 속도 계산이 요구되지 않고, 지령전류는 직접 두 신호의 위상차에 의해 결정된다. 전류 지령은 두 펄스 신호의 위상차에 따라서, 전동기의 속도를 일정하게 유지하기 위하여 변화된다. 제안된 방식은 매우 간단하지만 효과적인 속도 제어를 구현할 수 있다. 또한, 부드러운 토크를 발생하기 위하여 지령 전류는 가속 및 감속 패턴을 따라 변동하도록 설계되었다. 제안된 방식은 50W, 40,000[rpm]급의 소형 고속 BLDCM에 적용하여 실험하였다.

• 한국항공우주학회지
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• 제36권8호
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• pp.753-760
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• 2008

본 연구는 재진입 비행체인 Hope-X의 공력특성과 A/L 단계에 있어서 기준궤적 생성에 관한 것으로서 A/L 단계의 궤적생성을 위해서는 우선적으로 Hope-X의 양력계수와 항력계수가 필요하다. 이를 위해서 상용 유동해석 코드인 Fluent를 사용하여 Hope-X의 유동특성을 해석하였다. A/L 단계는 기준 궤적은 개념적으로 3개의 세부단계 : 기체 안정성을 위한 Steepglide Slope 단계, 안전한 착륙을 위한 Flare Maneuver 단계, 이 두 단계를 자연스럽게 연결시키는 Circular Flare단계로 이루어진다. 기준 궤적은 공력계수와 기체의 운동 특성을 고려하여 기하학적 경로식에 의한 각 단계의 경로각을 결정하는 방법을 통하여 생성된다.