• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.43-50
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• 2004

The clock skew is one of the major constraints for high-speed operation of synchronous integrated circuits. In this paper, we propose a hierarchical partitioning based clock network design algorithm called Advanced Clock Tree Generation (ACTG). Especially new effective partitioning and refinement techniques have been developed in which the capacitance and edge length to each sink are considered from the early stage of clock design. Hierarchical structures obtained by parhtioning and refinement are utilized for balanced clock routing. We use zero skew routing in which Elmore delay model is used to estimate the delay. An overlap avoidance routing algorithm for clock tree generation is proposed. Experimental results show significant improvement over conventional methods.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.390-400
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• 2013

The purpose of this study is to investigate the effect of RTE characteristics on SCM performance. Extant approaches for evaluating the SCM performance adopt financial measures, non-financial measures, Balanced Score Card (BSC) methodology and Supply Chain Operations Reference (SCOR) methodology etc., but researches on SCM performance measurement are not sufficiently reviewed. In this study, SCM performance is measured with the Combinative Capabilities which are divided into four categories of product quality, delivery speed, process flexibility, price leadership. The experimental results with the three factors of visibility, agility and combinative capabilities variables show the followings: (i) Visibility had a significant impact on agility. (ii) Visibility had a significant impact on combinative capabilities. (iii) Agility also had a significant impact on combinative capabilities.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.75-83
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• 2006

The purpose of this study was to investigate steady-state force depression following active muscle shortening in human tibialis anterior muscle during voluntary contractions. Subjects (n = 7; age $24{\sim}39$ years; 7 males) performed isometric reference contractions and isometric-shortening-isometric contractions, using maximal voluntary effort. Force depression was assessed by comparing the steady-state isometric torque produced following active muscle shortening with the purely isometric reference torque obtained at the corresponding joint angle. In order to test for effects of the shortening conditions on the steady-state force depression, the speed of shortening were changed systematically in a random order but balanced design. Ankle dorsiflexion torque and joint angle were continuously measured using a dynamometer. During voluntary contractions, muscle activation of the tibialis anterior and the medical gastrocnemius was recorded using surface electromyography. Force depression during voluntary contractions, with a constant level of muscle activation, was 12 %, on average over all subjects. Force depression was independent of the speeds of shortening ($13.8{\pm}2.9%$, $10.3{\pm}2.6%$ for 15 and 45 deg/sec over 15 deg of shortening, respectively). The results of this study suggest that steady-state force depression is a basic property of voluntarily-contracting human skeletal muscle and has functional implication to human movements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1A
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• pp.58-64
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• 2006

A 900-MHz band transceiver has been developed for RFID reader applications. In the transmitter, a GaAs SPST switch is used for high speed switching and low power consumption. In the receiver, a double balanced mixer is used to compress even-harmonic products. The ASK demodulator which consists of an active filter and comparator is used to reject the unwanted in band interferers. The transceiver produces a maximum transmitting power of 30 dBm and exhibits an 5 m communication range with a 6-dBi gain antenna.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.1
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• pp.71-86
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• 1997

The 297 middle school girls in Inchon were devided into three groups according to body mass index(BMI), the under weight group, the normal weight group and obese group to find out relationship between their food habits, food preference, and obesity. The average height and weight are 159.40cm, 67.02kg for obese group, 158.17cm, 39.11kg for under weight group, 156.93cm, 53.78kg for normal weight group. Obese group feels that they are healthy and fat, and their parents are fat also than the other groups. Obese group took more exercise. Total Food habits scores of obese group were lower than the other two groups. In terms of supper, bedtime-smack, unbalanced diet, balanced intake of five basic food groups obese group had lower scores. Especially, intake of carbohydrate, protein, milk group were irregular. There is no significant different in size of meal, overeating eating speed. The preferences of fast food, instant food, high caloric density food were lower in obese group than in the other two groups. The mother of obese group prepared meals according to food composition and prepared little snakes.

• Journal of Power Electronics
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• v.16 no.2
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• pp.675-684
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• 2016

This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.285-288
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• 1998

A least-squares identification method is studied that estimates a finite number of coefficients in the series expansion of a transfer function, where the expansion is in terms of recently introduced generalized basis functions, We will expand and generalize the orthogonal functions as basis functions for dynamical system representations. To this end, use is made of balanced realizations as inner transfer functions. The orthogonal functions can be considered as generalizations of, for example, the pulse functions, Laguerre functions, and Kautz functions, and give rise to an alternative series expansion of rational transfer functions. We show that the Laplace transform of the expansion for some sets$\Psi_{\kappa}(Z)$ is equivalent to a series expansion . Techniques based on this result are presented for obtaining the coefficients $c_{n}$ as those of a series. One of their important properties is that, if chosen properly, they can substantially increase the speed of convergence of the series expansion. This leads to accurate approximate models with only a few coefficients to be estimated. The set of Kautz functions is discussed in detail and, using the power-series equivalence, the truncation error is obtained.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.6
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• pp.303-309
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• 2020

A vehicle's differential gear is a device designed to allow the vehicle's outer wheels to turn faster than the inner wheels when turning on a curve. The differential gear case is the main component of the differential gear system, which is composed of ring gear, pinion gear and side gear, and is fastened by pinion shaft pins. The differential gear case rotates when the vehicle is running, so balancing calibration is very important. In this study, a balancing machine that can diagnose and correct the differential gear case and mass imbalance of various rotating bodies was designed. The differential gear case was rotated at high speed to accurately diagnose the location and value of the unbalanced mass, and it was designed to be balanced and corrected by removing the unbalanced mass by drilling. After calibration, it was confirmed that the unbalanced value of all the measured samples was reduced to less than 180g.mm, and the unbalance reduction ratio was improved to 60~70%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.170-181
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• 2020

In a situation where population decline is intensifying, the decline of local mid-small sized cities is emerging as a social problem. The decline will increase the difficulty of supplying demand-based living services. Therefore, increasing accessibility to living services is important for quality of life. With this background, the purpose of this study is to derive living zones that can use high-order services in metropolitan cities through high-speed railway. To this end, the behaviors of residents in mid-small sized cities were investigated through a questionnaire, and living zones and vulnerable areas were derived through a GIS analysis. The results of the study are summarized as follows. First, most of the residents had experience using cultural, medical, shopping, and educational services in metropolitan cities. Second, the time required to visit a metropolitan city for the use of higher-order services was about 2 hours, and the desired time was about 50 minutes. Third, when accessibility is improved, the willingness to use the higher-order service of the metropolitan city is high. Fourth, many regions have been derived as living zones where services of metropolitan cities can be used through high-speed rail. Lastly, the major vulnerable areas were found to be the northern area of the Gangwon region, the northern area of the Yeongnam region, the west coast of Chungnam, and the border area of Jeonnam and Gyeongnam.

• Journal of IKEEE
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• v.9 no.2 s.17
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• pp.152-160
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• 2005

A prescaler is an essential building block for PLL-based frequency synthesizers and must satisfy high-speed and low-power characteristics. The design of D-flip flips used in the prescaler implementation is thus critical. Conventional TSPC D-flip flops suffer from glitches, unbalanced propagation delay, and unnecessary charge/discharge at internal nodes in precharge phase, which results in increased power consumption. In this paper a new dynamic D-flip flop is proposed to overcome these problems. Glitches are minimized using discharge suppression scheme, speed is improved by making balanced propagation delay, and low power consumption is achieved by removing unnecessary discharge. The proposed D-flip flop is employed in designing a 128/129 dual-modulus prescaler using $0.18{\mu}m$ CMOS process parameters. The designed prescaler operates up to 5GHz while conventional one can operate up to 4.5GHz under same conditions. It consumes 0.394mW at 4GHz that is a 34% improved result compared with conventional one.