• International Journal of Oral Biology
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• 제34권2호
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• pp.53-59
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• 2009

Periodontal ligament (PDL) tissue is a connective tissue that is interposed between the roots of the teeth and the inner wall of the alveolar bone socket. PDL is always exposed to physiologic mechanical force such as masticatory force and PDL cells play important roles during orthodontic tooth movement by synthesizing and secreting different mediators involved in bone remodeling. The Wnt/${\beta}$-catenin signaling pathway was recently shown to play a significant role in the control of bone formation. In the present study, we applied cyclic tensile stress of 20% elongation to cultured human PDL cells and assessed its impact after six days upon components of the Wnt/${\beta}$-catenin signaling pathway. RTPCR analysis showed that Wnt1a, Wnt3a, Wnt10b and the Wnt receptor LRP5 were down-regulated, whereas the Wnt inhibitor DKK1 was up-regulated in response to these stress conditions. In contrast, little change was detected in the mRNA expression of Wnt5a, Wnt7b, Fz1, and LRP6. By western blotting we found decreased expression of the ${\beta}$-catenin and p-GSK-3${\beta}$ proteins. Our results thus show that mechanical stress suppresses the canonical Wnt/${\beta}$-catenin signaling pathway in PDL cells.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.901-904
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• 2007

오늘날 많은 의료영역에서 각종 영상 장치를 이용함으로 절개 과정 없이 인체 내부 장기를 가시화함으로 질병의 유무와 진행 상태 등을 관찰할 수 있게 된다. 이러한 장치의 한가지로 초음파 진단장치는 다른 장치에 비해 장비의 가격이 저렴하고 크기가 소형이라 이동 장치가 가능하고 특히 인체에 해를 주지 않고 장시간에 걸쳐 인체 내부를 실시간 관찰할 수 있게 해 줌으로 심장이나 태아의 운동 등을 관찰하는데 유용하게 사용된다. 또한 초음파 영상을 이용하여 각종 내과적 질환을 비관혈적 방법으로 관찰하고 인체 내 연조직 부분의 질병을 진단하는 수단으로 자주 이용 되고 있다. 이러한 초음파 진단장치는 펄스발생기를 통하여 발생된 초음파 펄스를 인체에 조사함으로 서로 다른 매질 사이의 경계면에서 발생하는 반사파와 각 매질내의 입자들에 의해 산란되는 산란파를 통하여 이루어진다. 이 때 평탄한 조직에 발생하는 반사파와 불규칙한 영역에 발생하는 산란파 간의 간섭으로 초음파 영상에는 여러 가지 잡음 특성들이 첨가되게 된다. 이에 본 논문에서는 초음파 태아 영상을 중심으로 그 특성을 조사 처리함으로 보다 개선된 화질의 초음파 영상을 얻고 이로부터 유효한 영역을 효과적으로 추출하고자 한다.

• 한국소음진동공학회논문집
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• 제16권1호
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• pp.40-49
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• 2006

A novel disturbance measurement method, model based disturbance observer (MBDO) for optical disk drives (ODDs), is proposed and the disturbance analysis using the proposed method is performed under various conditions. In ODDs, the quantitative and qualitative analysis for the generated disturbance during normal operation is very important to successful servo loop design. However, the disturbance measurement is difficult, and high precision measurement is necessary. Furthermore, the conventional disturbance measurement method using a LDV (laser Doppler vibrometer) has many difficulties in eccentricity direction due to the vertical movement of an optical disk. To solve this problem, the MBDO is proposed. First, the relationship between the servo loop for ODDs and the generated disturbance are briefly reviewed. Second, the principle of the MBDO is introduced, and the disturbance measurement results, which are measured by the MBDO and a LDV, are compared. In these experiments, test DVD-ROM disks are used to generate quantitative/qualitative disturbance. Then, the disturbance analysis under various conditions is performed using waterfall technique. This technique clearly shows the disturbance trend from the inner part of an optical disk to the outer part of it. Finally, the various disturbances measurement results are summarized and some remarks for it are commented.

• 천문학회보
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• 제36권2호
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• pp.115.1-115.1
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• 2011

We analyzed the line profiles of the planetary nebula (PN) NGC 7009 secured with the Keck I HIES and BOES's spectral data. The 5 positions were taken over the nebular image, 4 points on the bright rim plus 1 point at the central position. The covered spectral wavelength range was $3250{\AA}-8725{\AA}$ in these observations. We decomposed the lines of HI, HeI, HeII, CII, NIII, [ClIII], [NII], [OII], [OIII], [SII], [SIII], [ClIII], and [ArIII] using the IRAF and StarLink/Dipso. After correcting the Earth's movement and the PN's radial velocities, -48.6 & -48.9 km/s, respectively, for the Keck & BOES, we produced the line profiles in a velocity scale. The zero velocity at each line profile clearly indicates which part of the components is approaching or receding, giving a general information of the kinematical structure. Almost all of the low-to-medium excitation lines, such as [NII], [SII], [O III], and [ArIII], secured at the central position and four positions along the major & minor axes, showed 3 components, double peak + a wide wing component, suggesting the fast outflow structures are present. The overall geometry is a prolate shell which also has a fainter outer shell in the halo zone, but there appears to be some peculiar sub-structures inside the main shell. The high excitation He I, HeII, NIII lines which might be formed close to the inner boundary of the shell show unusual features, completely different from the other lines. The HeII and these high excitation lines may be indicative of a relative recent fast outflow from the central star and the permitted lines such as NIII might be affected by the innermost structure. We discuss a possible presence of a jet-like fast outflow structure in an out-flow axis different from the main axis of the spheroid shell.

• 대한기계학회논문집B
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• 제23권7호
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• pp.937-944
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• 1999

The near-wall flow structures of turbulent boundary layer over riblets having semi-circular grooves were investigated experimentally for the drag decreasing ($s^+=25.2$) and drag increasing ($s^+=40.6$) cases. The field of view used for tho velocity field measurement was $6.75{\times}6.75mm^2$ in physical dimension, containing two grooves. One thousand instantaneous velocity fields over the riblets were extracted for each case of drag increase and decrease. For comparison, five hundreds instantaneous velocity fields over a smooth flat plate were also obtained under the same flow conditions. To see the global flow structure qualitatively, the flow visualization was also performed using the synchronized smoke-wire technique. For the drag decreasing case ($s^+=25.2$), most of the streamwise vortices stay above the riblets, interacting with the riblet tips. The high-speed in-rush flow toward the riblet surface rarely influences the flow inside tho riblet valleys submerged in the viscous sublayer. The riblet tips seem to impede the spanwise movement of the longitudinal vortices and induce secondary vortices. The turbulent kinetic energy in the riblet valley is sufficiently small to compensate the increased wetted area of the riblets. In addition, in the logarithmic region, the turbulent kinetic energy are small or almost equal to that of a smooth flat plato. For the drag increasing case ($s^+=40.6$), however, the streamwise vortices move into the riblet valley freely, interacting directly with the riblet inner surface. The penetration of the high-speed in-rush flow on the riblets increases tho skin-friction. The turbulent kinetic energy is increased in the riblet valleys and even in the outer region compared to that over a flat plate.

• 디지털융복합연구
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• 제11권1호
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• pp.243-248
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• 2013

본 논문에서는 2D/3D 동영상 변환을 위해 깊이가 할당될 전경을 초점 정보와 색상분석 기반의 그룹화를 이용하여 추출하고, 전경의 깊이를 초점 정보와 움직임 정보를 이용하여 생성하는 방법을 제안하였다. 2D영상에서 전경을 추출하기 위해 영상의 초점 정보의 움직임을 추정하여 전경 후보 영상을 생성하고, 전경 후보 영상에 존재하는 객체 내부의 홀 영역을 색상 분석을 이용한 채움 과정을 수행하여 전경 영역을 추출하였다. 생성된 전경 영역에 깊이를 할당하기 위해 해당 프레임에 존재하는 초점 값을 분석하여 초기 깊이 정보를 생성하고 움직임 정보를 가중하여 깊이 정보를 할당하였다. 생성된 깊이 정보의 품질을 평가하기 위해 기존에 제안된 알고리즘의 결과 영상과 비교하였다.

• Nuclear Engineering and Technology
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• 제26권2호
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• pp.197-204
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• 1994

원자로운전정지시 사용되는 제어봉집합체는 제어봉구동장치에서 분리되어 핵연료집합체의 안내관으로 자유낙하한다. 이 제어봉집합체의 주요변수로는 낙하시간과 충격속도가 있는데, 낙하시간은 원자로 안전정지와 관계가 있으며, 충격속도는 핵연료집합체의 건전성과 관계가 있다. 따라서, 제어봉 낙하시간과 충격속도의 적절한 결정은 제어봉집합체와 핵연료집합체의 설계에 매우 중요하다. 제어봉집합체는 낙하도중 유체저항이나 마찰력 및 부력과 같은 여러 힘들에 의해 낙하시간이 감소하게 되는데, 이러한 여러가지 힘의 복잡한 결합으로 인해 낙하시간과 충격속도를 해석적으로 유추하는 것은 매우 어렵다. 본 논문에서는 국산핵연료집합체에 적용되는 해석적인 방정식을 포함하고 있는 프로그램을 개발하였고, 이 프로그램을 단일제어봉 낙하시험과 비교하였다. 비교결과 시험 및 해석결과가 잘일치하고 있음으로써 개발된 프로그램의 검증을 확인할 수 있었고, 따라서 이 프로그램이 제어봉및 안내관의 설계변경시 매우 유용하게 사용할 수 있게 되었다.

• 한국항해항만학회지
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• 제29권4호
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• pp.327-333
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• 2005

Sea level (MSL, MHWL, or MLWL) change has been main concern to scientists and engineers and it can be primarily due to both change of climate and vertical movement of land. This paper reports the intensive analysis of the sea level changes and broad discussion of the future at the southwestern coast of Korean peninsula. Regression analysis was conducted to investigate general tendency and periodicity of the sea levels at the six different study sites such as Gunsan-I(inner port), Gunsan-O(outer port), Mokpo, Yeosu, Heuksan and Jeju and the results were compared with global values. Besides the changes of sea levels due to global warming, the influence of the man-made structure such as seadike and seawall was attempted to quantify using the minimization of the Root Mean Square(RMS) error. The results show that it is a general tendency that the values of mean sea level rise at the southwestern coast of Korean Peninsula, especially at Gunsan-I and Jeju, are somewhat larger compared to global average values. There is also some evidence that tidal amplifications are found just after construction of man-made structure at Gunsan-I and Mokpo. However, both sites show different mechanism in relation to tidal choking, tidal flat and river discharge. The impact due to construction of man-made structure is considerably larger at Mokpo site, while the impacts due to man-made structure and the effect of sea level rise are relatively identical at Gunsan-I site. This study is expected to provide some intuition to future design.

• 한국지능시스템학회논문지
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• 제20권3호
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• pp.311-317
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• 2010

본 논문에서는 미지 환경의 비평탄 지형에서 로봇 주행에 제한이 따르는 문제를 극복하기 위해 물리적 결합을 통한 모듈형 로봇의 이동성 향상 기법을 제안한다. 모듈형 로봇 시스템은 자가 결합 기구 장치, 3자유도 로봇 결합 팔, 모듈 로봇 플랫폼, 모션제어기, 주제어기로 구성하였으며, 로봇간 결합 및 협업을 위해 RGGR구조의 결합 메카니즘을 사용하였다. 또한 실내 GPS를 사용하여 로봇의 실시간 위치 및 진행 방향을 추정하고, 추정된 정보를 기반으로 로봇의 이동 경로와 방향을 제어하여 로봇간 물리적 결합을 수행하였다. 물리적 결합을 통한 모듈형 로봇의 비평탄 지형 주행 알고리즘의 성능을 검증하기 위해 세 대의 모듈형 로봇을 제작하여 실제 끊어진 도로와 단턱이 존재하는 환경에서 실험을 통해 검증하였다.

• 한국태양에너지학회 논문집
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• 제28권5호
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• pp.14-20
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• 2008

As the number of buildings that use the transparent permeation materials as the outer wall is on the increase, the coming amount of the light rays is a lot, and thus the increase in the cooling load and the radiant heat of high temperature may cause the residents to discomfort. In order to reduce such influences, this paper analyzed the installation effects of the sunshade BIPV. The inner temperature of the room installed the sunshade BIPV or otherwise was measured, and compared and analyzed the effects of reducing the cooling load by the incoming light rays. The sample space of the third floor of S university installed the sunshade BIPV has two rooms on the same conditions, and for five sunny days selected in August, the researcher measured the air temperature and the temperature of the fittings with closing the windows to minimize the movement of air without operating the coolers. The maximum cooling load measured by the incoming light rays in the room where the sunshade BIPV was not installed was examined as 459.13kcal/h. It can be understood as the effect of reducing the cooling load according to the incoming rays of the room with sunshade BIPV. Even though the effect of cooling load reduction is not so great in a room, the total reduction in cooling room for the 32 rooms installed the sunshade BIPV was estimated to be 40442.27kcal/day, which will be able to bring the maximum reduction effect of 17.1kW in energy and reduce the investment cost owing to the reduction in cooling load when initially designing the building.