• Transactions of the Korean hydrogen and new energy society
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• v.12 no.3
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• pp.231-238
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• 2001

Electrocatalytic activity of palladium for hydrogen oxidation and reduction was studied using AC impedance method. The system under study was arranged in electrolytic mode consisting of Pd electrode under study, Pt counter electrode and Nafion electrolyte between them. Two types of Pd electrodes were used - carbon-supported Pd (Pd/C) and Pd foil electrode. Pd/C anode contacting pure hydrogen showed a steady decrease of charge transfer resistance with the increase of anodic overpotential, which is an opposite trend to that found with Pd foil anode. But Pd foil cathode also exhibited a decrease of the resistance with the increase of cathodic overpotential. The relationship between imposition of overpotential and subsequent change of the charge transfer resistance is determined by the ratio of the rate of faradaic process to the rate of mass transportation; if mass transfer limitation holds, increase of overpotential accompanies the increase of charge transfer resistance. Regardless of the physical type of Pd electrode, the anode contacting hydrogen/oxygen gas mixture did not reveal any independent arc originated from local anodic oxygen reduction.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.89-97
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• 2011

This paper considers improved IGM (Iterative Guidance Mode), one of the explicit guidance algorithms, to determine the guidance algorithm for upper stages of a space launch vehicle. IGM, which has been employed successfully for the Saturn to put its payload into the parking orbit and lunar transfer orbit, is applied here for guidance of the launcher during the second and third stages. The orbit injection accuracy is evaluated through the 3-DOF computer simulations and an accurate prediction method, which can eliminate the prediction error of the downrange position at the orbit injection, is also proposed here.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1303-1310
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• 2007

In IEEE 802.11b wireless network, stations synchronize themselves to the beacons periodically sent by the access point (AP) when they are running in low power mode. Stations stay awake for enough time to receive beacon because it is delayed in AP if the wireless channel has been being used by other traffic at each scheduled instant. In this paper, we propose a method that measures the delay of received beacons and calculates wake-up interval of station to receive the next one. Beacon transmission delay at the AP is analyzed. The proposed method is simulated and its characteristics are described in the analysis. The result measured in terms of station's wake-up interval shows some enhancement in energy consumption.

• The Journal of Korean Physical Therapy
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• v.8 no.1
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• pp.81-89
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• 1996

This study is to make legal suggestions concerning the legal status of the physical therapists and the their clinics io Korea. This study compares the legal status of the physical therapists with that of the optical and dental technicians, and reviews the current system of the American physical therapeutic clinic. 1. Under the supervision of the doctor or dentist' in Article 1 of Law concerning the Medical Technician should be deleted or changed into 'by the request of the doctor or dentist'. A new independent law should be mode only fer the physical therapist from the general law that stipulates the legal status of other similar medical technicians. 3. The legal status of the physical therapeutic clinic should be stipulated in the regulations for the application of the law as that of the dental technician does. The modification of the medical services, the medical expences, waiting time, the easy access to the clinic of farmers, fishermen, urban laborers, and handicapped people, and the development of the area of the physical therapy.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.311-316
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• 2005

The experimental study for an operational characteristics and performance of the sodium heat pipe were carried out. For an experiment. the heat pipe which is 1000mm length and 25.4mm diameter of stainless steel container with 50 mesh of screen wick using sodium as a working fluid is manufactured and tested as functions of heat flow rate, inclined angle and operating temperature. The test results are as follows. During the start-up. frontal start up was observed because of the vapor density increasing as increased the hot zone. Also, the heat pipe showed uniform temperature over than $420^{\circ}C$ of the operating temperature. The average heat transfer coefficient increased as the heat flux and the vapor temperature increase, and the range of the total thermal resistance was 0.075-0.04 $^{\circ}C/W$ at the 12-53.55 $kW/m^2$ of heat flux and $500-750^{\circ}C$of operating temperature. The maximum heat flow rate was 750W at the 10 degree of top heating mode.

• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.409-422
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• 2001

The dynamic character of a system of the governing differential equations for the one- dimensional two-fluid model, where the momentum flux parameters are employed to consider the velocity and void fraction distribution in a flow channel, is investigated. In response to a perturbation in the form of a＇traveling wave, a linear stability analysis is peformed for the governing differential equations. The expression for the growth factor as a function of wave number and various flow parameters is analytically derived. It provides the necessary and sufficient conditions for the stability of the one-dimensional two-fluid model in terms of momentum flux parameters. It is demonstrated that the one-dimensional two-fluid model employing the physical momentum flux parameters for the whole range of dispersed flow regime, which are determined from the simplified velocity and void fraction profiles constructed from the available experimental data and $C_{o}$ correlation, is stable to the linear perturbations in all wave-lengths. As the basic form of the governing differential equations for the conventional one-dimensional two-fluid model is mathematically ill posed, it is suggested that the velocity and void distributions should be properly accounted for in the one-dimensional two-fluid model by use of momentum flux parameters.s.

• Clinical and Experimental Pediatrics
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• v.45 no.10
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• pp.1278-1282
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• 2002

Glutaric aciduria(type 1) is characterized clinically by progressive dystonia and dyskinesia in childhood, pathologically by degeneration of caudate and putamen, biochemically by tissue deficiency of glutaryl-CoA dehydrogenase(GCDH), and is transmitted as an autosomal recessive traits. Mutations of the GCDH gene on chromosome 19 have been implicated in the causation of glutaric aciduria(type 1). Macrocephaly in infancy and crossing of percentiles for head circumference are real clues to early diagnosis. Acute neuroregression of dystonia following an initial phase of normal or almost normal development is a common mode of presentation, at times preceded by seizures. We experienced a case of glutaric aciduria(type 1) in a 13-month old girl. She was admitted due to development delay and choreoasthetoid movememt that developed after generalized tonic-clonic type seizures. She was diagnosed as having glutaric aciduria(type 1) based on brain MRI and urine organic acid analysis finding.

• Journal of Korea Foundry Society
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• v.27 no.5
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• pp.209-211
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• 2007

최근에는 탄소섬유강화복합재료(CFRP)는 우수한 기계적인 물성치와 수월한 설계특성으로 인해 우주.민간 항공산업분야 뿐만 아니라 여러분야에 응용성이 매우 높다. 그러나 CFRP 복합적층판으로 제작된 구조물은 충격손상을 받을 시에는 50-75%치 강도가 낮아지는 취약성을 가지고 있다. 따라서 본 연구에는 CFRP복합재의 구조건전성 및 결함여부를 비파괴적으로 검사 및 탐상을 하기 위해서 시도하였다. 특히, C-scanner의 수침조에서 충격손상을 받은 시험편을 집어넣어 자동 데이터 획득 시스템을 구동하여 현장응용성이 가장 높은 일 방향 초음파측정 (one-sided ultrasonic measurement) 방법인 평가기법을 제안하였다. 본 연구에서 제안한 일방향 초음파 피치캐치방법이 CFRP 복합적층판내에서 일반 수직 초음파 탐상기법보다 훨씬 민감함을 알 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.1
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• pp.1-6
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• 2001

In this paper we reanalyze Kohonen‘s learning vector quantizing (LVQ) Learning rule which is based on Hcbb’s learning rule with a view to a gradient descent method. Kohonen's LVQ can be classified into two algorithms according to 6learning mode: unsupervised LVQ(ULVQ) and supervised LVQ(SLVQ). These two algorithms can be represented as gradient descent methods, if target values of output neurons are generated properly. As a result, we see that the LVQ learning method is a special case of a gradient descent method and also that LVQ is represented by a generalized percetron-like LVQ(PLVQ).

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.3
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• pp.11-16
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• 2000

In this paper, a real-time implementation of scene-based non-uniformity correction by digital technique is proposed for microscan-mode staring infrared cameras. Most scene-based non-uniformity correction algorithms, without sensor motion, can not be applied to stationary scenes because of image blurring and fading. Using microscanning effect, coupled with a modified version of Scribner's algorithm, the proposed technique can correct the artifacts and non-uniformities in real time Computer simulations and hardware experiments demonstrate substantial Improvement of image qualities in stationary as well as moving scenes.