• 한국컴퓨터정보학회논문지
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• 제26권4호
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• pp.143-147
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• 2021

본 연구의 목적은 정상 범위보다 큰 명치각을 가진 대상자들에게 가슴벨트 적용이 척추 안정성에 어떠한 영향을 미치는지에 대하여 알아보고자 하였다. 정상 범위보다 큰 명치각을 가진 총 15 명의 대상자가 본 연구에 참여했으며 가슴벨트 적용 유-무의 조건에서 능동적 두 다리 내리기와 능동적 한 다리 올리기가 수행되었다. 가슴 벨트 적용 여부에 따라 수행 된 두 가지 척추 안정성 테스트 (능동적 두 다리 내리기와 능동적 한 다리 올리기)는 각 조건 간에 유의 한 차이를 보였다. 본 연구의 결과에 따르면, 가슴벨트 적용은 비정상적으로 증가된 명치각으로 인해 척추 또는 몸통 불안정성을 가진 대상자에게 척추를 안정화 시켜줄 수 있는 효과적인 치료적 방법으로 여겨진다.

• 한국자동차공학회논문집
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• 제17권2호
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• pp.42-48
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• 2009

This paper is the second of 2 companion papers which investigate in-cylinder swirl generation characteristics according to inlet valve angle. Two DOHC 4 valve engines, one has wide intake valve angle and the other has narrow valve angle, were used to compare the characteristics of swirl motion generation in the cylinder. One intake port was deactivated to induce swirl flow. A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake stroke. The results show that the flow patterns of narrow valve engine are much more stable and well arranged compared with the normal engine over the entire intake and compression stroke except early intake stage, and very strong swirl motion is generated at the end of compression stage in this engine nevertheless using straight port which is unfavorable for swirl generating. In the wide valve angle one, however, strong swirl motion induced during intake stroke is destroyed as the compression progresses.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.668-673
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• 2000

Spud angle( ${\alpha}$ ) and fuel injection angle ( ${\beta}$ ) have strong influence on spud type gas burner combustion. A wide range of flame stability is shown at ${\alpha}=60^{\circ}$, but at ${\alpha}=30^{\circ}$ is narrow. Optimum condition of flame stability swirl angle( ${\gamma}$ ) is $40^{\circ}$. At condition of ${\alpha}=30^{\circ}$ flame shape is relatively narrow and long, on the other hand, at ${\alpha}=60^{\circ}$ flame is wide and short. Regardless of spud angle, maximum flame temperature shows in the range of Z=200mm and R=0mm. Flame temperature, on the whole, is high at ${\alpha}=45^{\circ}$. At ${\alpha}=45^{\circ}$, NOx emission is higher than other conditions that may be concerned with flame temperature. At ${\beta}=60^{\circ}$ and ${\gamma}=40^{\circ}$, NOx emission is reduced due to fuel injection angle.

• Macromolecular Research
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• 제14권6호
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• pp.588-595
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• 2006

The morphology, structure and melting behaviour of cold-crystallized isotactic polystyrene (iPS) were studied by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS). The polymer was found to crystallize according to the dual-lamellar stack model. The two populations of lamellae, along with a melting-recrystallization phenomenon, determined the appearance of multiple melting peaks in DSC traces. The annealing peak was attributed to the relaxation of a rigid amorphous phase, rather than to the melting of crystalline material.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.9-10
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• 2000

The wide viewing angle and fast response time characteristics of negative dielectric anisotropy nematic liquid crystal (NLC) using a novel vertical-alignment (VA) - 1/4 ${\pi}$ cell mode on a homeotropic alignment layer were investigated. Good voltage-transmittance curves and low driving voltage using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film were obtained. The iso-viewing angle characteristics of NLC using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film can be achieved. The fast response time of 24.4 ms in NLC was successfully measured. The iso-viewing angle, fast response time, and low driving voltage characteristics using the novel VA - 1/4 ${\pi}$ cell mode can be achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.800-802
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• 2006

A simple wide-viewing-angle solution of electrically controlled birefringence (ECB) LCD is proposed, which is based on a single discotic compensation film. The use of a single discotic film instead of two leads to a considerable reduction in cost while high performance is maintained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.107-107
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• 2004

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.1-4
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• 2000

We have developed a high performance vertical alignment TFT-LCD, that shows a high light transmittance, and wide viewing angle characteristics with an unusually high contrast ratio. In order to optimize the electro-optical properties we have studied the effect of cell parameters, multi-domain structure and retardation film compensation. With the optimized cell parameters and process conditions, we have achieved a 24" wide UXGA TFT-LCD monitor (16:10 aspect ratio 1920X1200) showing a contrast ratio over 500:1, panel transmittance near 4.5%, response time near 27 ms, and viewing angle higher than 80 degree in all directions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2204-2209
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• 2008

Flame pattern in burner used in steel industry that constitutes 30% of country energy consumption is generally characterized as long narrow flame pattern so that localized heating causes product quality worse and many burners are needed for proper heating. This paper deals with flat wide flame pattern which has advantage in terms of uniform heating using less number of burners. For that purpose, impinging jet system of fuel and oxidant was used for making flat wide flame. Results show that nozzle angle $75^{\circ}$ of impinging jet is found to be optimum configuration for making effective wide flame which has uniform radiation heat transfer and flame temperature is also most uniform along the flame width for that nozzle angle.

• Journal of Power Electronics
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• 제18권3호
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• pp.714-722
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• 2018

This paper presents a wide-range speed control scheme of brushless DC (BLDC) motors based on a hall sensor with separated low- and normal-speed controllers. However, the use of the hall sensor signal is insufficient to detect motor speed in the low-speed region because of low sensor resolution and time delay. In the proposed method, a micro-stepping current control method according to the torque angle variation is presented. In this mode, the motor current frequency and rotating angle are determined by the reference speed without the actual speed fed by the hall sensor. The detected torque angle is used to adjust the current value in a limited band to control the current value in accordance with the load. The torque angle is detected exactly at the changing point of the hall sensor signal. The rotor can follow the rotating flux with the variable torque angle. In a normal speed range, the conventional vector control scheme is used to control the motor current with a PI speed controller using the hall sensor. The torque characteristics are analyzed on the basis of the back EMF and current shape. To adopt the vector control scheme, the continuous rotor position is estimated by the measured speed and hall sensor position. At the mode changing point between low and normal speed range, the proper initial current command and reference rotor position are calculated. The calculated current command can reduce the torque ripple during transient mode. The proposed method is simple but effective in extending the speed control range of a conventional BLDC motor with hall sensor without the need for a high-resolution encoder. The effectiveness of the proposed method is verified by various experiments on a practical BLDC motor.