• Journal of Astronomy and Space Sciences
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• 제9권2호
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• pp.203-212
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• 1992

인공위성의 자세결정을 위해 3축 magnetometer에 의해 측정된 지구 자기장의 자료와 IGRF 모델(tilted-eccentric dipole 모델)을 사용하였다. 지구자기장 모델으 값들을 계산하여 magnetometer 측정자료들과 비교해 보았고 이것으로부터 두 자세각 $\alpha$ 각과 $\beta$들을 구하였다. 이 두 각들을 이용하여 자세결정에 사용되는 Z 축과 자기장의 수직성분 사이의 실 자세각 $\gamma$ 에 대한 bound $\gamma1$과 $\gamma2$를 계산하여 UoSAT-11, 14, 22의 자세 상태를 알아보았다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.357-360
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• 2005

A novel wide viewing angle flexible liquid crystal display will be demonstrated. The crossed matrix-type micro-cell structure was adopted in this design. The LC domains were divided into four different tilted directions by the combination effect of pixel fringe field and crossed matrix type micro-cell. It can create four domains without rubbing process and form the cell gap without spacer. For flexible color fabrication, a novel inkjet printing technology is adopted. This cost effective wide viewing angle color flexible LCD technology can be a good solution for high performance flexible LCD.

• 전자공학회논문지D
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• 제35D권12호
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• pp.83-91
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• 1998

광섬유 코어로 입사된 빛이 임의의 경사 각도를 가지는 광섬유 브래그 격자를 만나면 광섬유 코어로 반사되는 주모드 외에 클래딩으로 결합되는 사이드모드가 발생한다. 이러한 사이드 모드는 클래딩 모드와 커플링 되어 특정 파장의 빛을 제거하여 없애는 장주기 광섬유 격자와 동일한 특성을 지닌다. 본 논문에서는 게르마늄이 많이 첨가된 depressed index type 광섬유와 수소처리를 하여 광민감성을 매우 높인 step index type 일반통신용 광섬유등 두 가지 광섬유에 대해 광섬유 브래그 격자의 정렬 각도에 따른 사이드 모드의 특성을 관찰하였다. 또한, 0.02°의 정밀도를 가진 회전판에 설치된 위상 마스크로 경사각도가 다른 각각의 광섬유 격자를 동일한 광섬유에 일렬로 새겨서 전체 손실 스펙트럼의 선폭과 피크값을 조절할 수 있었으며, 이를 이용하여 광섬유 광 증폭기의 ASE 대역 제거 필터 구성 실험을 수행하였다.

• 한국전문물리치료학회지
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• 제28권2호
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• pp.117-122
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• 2021

Background: Flat-back posture refers to a posture in which the pelvis is tilted backward, the lumbar spine is bent, the upper thoracic spine is increasingly bent, and the lower thoracic spine is straight. Given that most of the day is spent sitting, we need to develop exercise programs and devices that are suitable for people who spend less time exercising than sitting. Objects: This study investigated the effects of resistance footrest exercise on spine posture angles in visual display terminal (VDT) workers with flat back. Methods: We measured the upper lumbar angle (ULA) and lower lumbar angle (LLA) using a flexible ruler for the ULA and LLA. Then, after 1 week of resistance footrest exercise designed to strengthen the lumbar spine musculature, we measured these angles again. We measured each angle three times and then compared measurements from before and after exercise. Results: There were no significant differences in the ULA following the strengthening exercise, but significant differences were observed in LLA. Conclusion: The resistance footrest exercise strengthened the muscles affecting the pelvic and lumbar lordotic angles, and increases in the LLA were changed. This suggests that the role of the lower lumbar spine in the lumbar lordotic curve is greater than that of the upper lumbar spine. In addition, considering the contemporary tendency to lead fairly sedentary lives, these results indicate that exercising while seated can be effective.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.852-858
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• 2007

This paper investigates the dynamic characteristics of a tilted HDD spindle system with fluid dynamic bearings (FDBs). Tilting motion of a HDD spindle system may be caused by improper manufacturing tolerance, such as imperfect cylindricity between shaft and sleeve of FDBs, imperfect perpendicularity between shaft and thrust as well as the gyroscopic moment of the unbalanced mass of the rotating part. Tilting motion may result in the instability of the HDD spindle system and it may increase the disk run-out to limit memory capacity. This research proposes a modified Reynolds equation for the coupled journal and thrust FDBs to include the variable film thickness due to the cylindricity and the perpendicularity. Finite element method is used to solve the Reynolds equation for the pressure distribution. Reaction forces and friction torque are obtained by integrating the pressure and shear stress, respectively. The dynamic behavior is determined by solving the equations of a motion of a HDD spindle system in six degrees of freedom with the Runge-Kutta method to study whirling and tilting motions. This research shows that the cylindricity and the perpendicularity increase the tilting angle and whirl radius of the rotor.

• Progress in Superconductivity
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• 제9권2호
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• pp.140-145
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• 2008

We report on the Josephson vortex dynamics in $Bi_2Sr_2CaCuO_{8+\delta}$ natural Josephson junctions by c-axis tunneling measurements. Beside the quasiparticle branches in the current-voltage characteristics, a new set of multiple branches, referred to as Josephson-vortex-flow branches (JVFBs), are observed. The JVFBs emerge in an in-plane magnetic field above $H_0\;=\;{\Phi}_0/{\gamma}s^2$ and show highly hysteretic behavior, which can be explained in terms of the recently proposed dynamic-phase-separation model. In this work we examined the effect on the JVFBs by the presence of pancake vortices generated as the external magnetic field was applied slightly tilted from the in-plane direction. JVFBs were found to become larger and prominent with increasing pancake vortex density as the tilt angle increased, which were presumably caused by slowing down of a Josephson vortex lattice in the presence of pancake vortices.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1424-1429
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• 2004

Distillation is one of many processes that can be used for the purification of water. It requires an energy input such as heat and solar radiation is a possible source of energy. In this process, water is evaporated, thus separating water vapor from the solute. The vapor is then condensed to pure water. The temperature of the water, the cavity of the enclosure and the surface of the glass was measured everyday. Fifteen points were chosen for the temperature measure using a thermocouple. The inner wall and the bottom of each still was painted black for good absorption of heat. The enforced glass was used for the cover for the entering of solar energy. The size of all of the water baths was the same, but the glass of the rectangular form had a tilted angle. In the case of fine or general weather, the volume of condensed water produced by $45^{\circ}$ and $60^{\circ}$ is very irregular compared to that of $15^{\circ}$ and $30^{\circ}$, In case of a rainy day, the occurrence of the volume of condensed water was similar to that of $15^{\circ}$ and $30^{\circ}$, but the volume of condensed water produced by $30^{\circ}$ was the highest.

• 천문학회보
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• 제36권1호
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• pp.62.1-62.1
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• 2011

Warp phenomenon seems to be ubiquitous among spiral galaxies, and a a number of mechanisms have been suggested as the origin including cosmic infall and tidal interactions. In this work, we compare warp characteristics of cluster spirals and the ones in the field in order to investigate the influence of environment on warping, in particular of gas disks. We make use of a tilted-ring modeling (TRM) method to VLA HI (21cm) data cubes of carefully selected 20 spiral galaxies in the Virgo cluster. The TRM allows us to probe kinematics, e.g., inclination, position angle, and velocity dispersion of HI disks. We compare the properties of each tilted-ring component to mean properties based on optical images. In this contribution, we present preliminary yet important findings on the warp characteristics of spiral galaxies in dense environment, and discuss possible origins of those kinematical structures.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 추계종합학술대회
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• pp.151-155
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• 1999

본 논문에서는 개구 급전 마이크로스트립 야기 배열에 의한 빔 틸팅 안테나를 제안하고, Ansoft사의 Ensemble 5.1을 이용하여 설계 변수들의 값을 추출하고 제작된 안테나의 성능을 측정 분석하였다. 제안된 안테나는 북반구 대부분 지역에서 고정위성 지향을 위해 3dB 빔 폭은 45$^{\circ}C$ 를 중심으로 +/- 2$0^{\circ}C$ 정도의 빔 커버리지를 가지며, 2.51GHz ~ 2.59GHz의 동작 대역을 가진다. 안테나의 구조는 반사기, 구동기, 유도기의 3개 구형 패치로 구성된다. 2.56GHz에서 제작된 안테나의 최대 이득은 앙각 42$^{\circ}C$ 에서 6.2dB, 그리고 Front-to-Back 비는 약 13dB 이상을 얻었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.582-585
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• 2004

Most of hard disk drives currently employ fluid dynamic bearing (FDB) for their rotor support. Stiffness of the FDB is affected by many design factors such as bearing clearance, fluid viscosity, and rotational speed. For the high rotating speed HDDs stiffness of the rotor is normally high enough to accomodate load disturbances. However small form factor HDDs that are to be operated in low power consumption are often designed with low stiffness rotors. Although the low stiffness rotor clearly benefits low power operation, it could damage the entire motor structure or head disk interface even by a light mechanical load disturbance such as shock or vibration. In addition, since a single channel HDD does not provide gram load equilibrium in axial direction the rotor could be tilted and make a hard contact to stator. A non-symmetric groove pattern could successfully compensate the tilted rotor angle during operation.