• Water for future
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• v.26 no.4
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• pp.97-105
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• 1993

This paper presents the results of a study conducted to improve the understanding of the characteristics of cylindrical capsule flow in a pipeline by taking into account of the effect of capsule density uniformity. The effect of capsule density variation in the axial direction was studied both experimentally and anaytically. The experiments were conducted in a 190mm diameter straight pipe 17m long. The velocity, gap and tilt of capsules were measured under various conditions, In order to interpret the data on various capsule density conditions, the stability index given in the dimensionless number was introduced. The motion of capsules in pipelines is strongly affected by the stability of the capsules characterized by the stability index. The experiments conducted prover that the stability index is a valid criterion for explaining and correlating data on the capsule motion and the capsule density uniformity.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.603-607
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• 2006

최근 산불발생이 증가하고, 그에 따른 피해가 증가하고 있다. 또한 산불 발생지역의 토양침식으로 인한 2차적인 재해위험이 예상됨에 따라 산불 지역의 토양침식과 영향인자들에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 낙산사 산불지역의 산지사면에 10개의 소규모 조사구를 설치하고 강우에 따른 토사유출량을 조사하였다. 토양침식 매개변수를 강우인자(강우량, 강우강도, 강우에너지), 지형인자(면적, 사면경사, 사면길이, 길이경사인자), 식생인자(전체피복도, 식생지수), 토양인자(투수계수, 유효입경, 유기물함량, 토심)로 구분하여 각각의 토양침식에 대한 관계를 분석하고, 시간경과에 따른 토양침식의 관계도 분석하였다. 강우강도와 강우량이 커짐에 따라 토양침식민감도에 대한 식생피복도의 영향이 더욱 가중되며, 식생 회복이 빠른 지역과 그렇지 않은 지역에서의 시간경과에 따른 누적 토양침식량의 변화는 크게 차이를 보였다. 낙산사 산불지역에서의 강우에 따른 토양침식은 강우에너지와 식생피복도의 관계가 가장 높았다.

• Journal of the Korea Computer Graphics Society
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• v.10 no.3
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• pp.9-16
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• 2004

가상환경의 표현 정보가 의미있는 데이터로서 사용되게 하기 위해서는 지구상 모든 물체를 유일하게 정의하고 표현할 수 있는 데이터 구성 체계가 요구된다. 이를 위해서는 화면에 표현할 물체의 속성 정보가 표준화된 기술 방법에 따라서 표현되어야 한다. 이것은 가상환경 정보가 실세계 정보처리 분야에서 의미있는 데이터로서 유효하게 사용되도록 하기 위해서 모든 물체에 대한 고유한 물리적 정보 기술 방법이 고려되어야 함을 의미한다. 여기에는 물체 표현에 필요한 외관에 관한 정보 뿐 아니라 물체의 내부 표현을 포함하여 물체의 기능 및 성능 표현, 길이 및 무게, 지리적 위치 등의 속성 정보까지 모두 표현되고 관리될 수 있어야 한다. 본 논문에서는 이와 같은 속성 기술 방법을 위해서 lSO/IEC JTC1 SC24 WG8에서 표준화작업을 진행하고 있는 SEDRIS를 이용하여 물체의 모습과 속성을 표현하는 데이터구조를 가시화하고 이 데이터구조에 따라 물체의 모습을 렌더링하고 조작하는 가상환경 표현 인터페이스 구현에 대해 설명한다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.4
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• pp.262-266
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• 2013

In OFDM system, cyclic prefix (CP) is used to eliminate the inersymbol interference that is caused by the channel dispersion. However, a long CP reduces the data transmission rate. An alternative to a logn CP is the a time domain channel shortening filter at the receiver that shortens the effective channel, thus a short CP is used in spite of a long channel impulse response. In the paper, we compare a various channel shortening techniques; minimum shortened signal to noise ratio (MSSNR), minimum interblock interference (min-IBI), and minimum ISI (min-ISI).

• Journal of Korea Multimedia Society
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• v.15 no.11
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• pp.1273-1283
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• 2012

In this paper, vision-based positioning algorithm for melon harvesting robot is presented. RGB value of the input image was converted into HSI value then, melon area was extracted after performing the binarization using HUE value. After morphological filtering was applied to remove noise, outermost boundary points were obtained using border following and convex hull method. Elliptical fitting for melons was perform by the RANSAC algorithm, the center point of ellipse, the length of the short and long axis, and rotation angle were obtained. We verified the effectiveness of the proposed method by various simulation experiments and confirmed actual feasibility of the proposed method by applying to the real melon.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.133-141
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• 2001

A tubular member holding an axially through-gusset connection is often used to transmit axial compression in a steel truss structures. The elastic buckling loads of the member is affected by the stiffness ratio($\beta$) and the length ratio(G) because of two elements with different properties. In current code, however, the strength is evaluated with an effective length factor k=0.9 without considering the above effect. Therefore this study analyzed a theoretical mechanism based on the elasticity theory and performed a finite element analysis to investigate the influence parameters on the elastic buckling strength of axially loaded member.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.175-180
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• 1998

Nd:YAG single crystal widely used as solid state laser was grown by Czochralski method. <111> single crystal with 0.9at% of $Nd^{3+}$ was grown from the Czochralski furnace with a automatic diameter control system. The vertical temperature gradient in the liquid was the major factor that influence the crystal quality, and the crystal diameter was controlled by the home made computer program. The crystal boule with $\phi$50mm$\times$ι100mm effective size was cut, polished, and antireflection coated. The optical evaluation such as absorption spectrum, fluorescence spectrum coincide with typical features of Nd:YAG single crystal. The laser rod was assembled into the CW laser generator with a Kr lamp. The maximum CW laser output was 70 W and the threshold power and efficiency was 1.3kW and 1.64% respectively.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.12
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• pp.70-77
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• 1999

A new method for fabricating long fiber Bragg gratings(FBGs) using uniform phase mask is proposed. The proposed method is characterized by forming a number of subgratings sequentially in series and varying linearly the effective refractive index of each subgrating. The reflectivity of a 200mm long uniform FBG developed fabricated by the method is about 95%. Also, the bandwidth and dispersion slope of a 250mm long linear-chirped FBG developed here are ∼0.5nm and ∼4.965ps/nm respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 1993.07a
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• pp.483-490
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• 1993

This paper presents the results of a study conducted to improve the understanding of the characteristics of cylindrical capsule flow in a pipeline by taking into account of the effect of capsule density uniformity. The effect of capsule density variation in the axial direction was studied both experimentally and analytically. The experiments were xonducted in a 190mm diameter straight pipe 18m long. The velocity, tilt of capsules and the gap between the capsule bottom and the pipe bottom were measured under various conditions. In order to interpret the data on the various capsule density conditions, the stability index given in the dimensionless numberwas introduced. The motion of capsules in pipelines is strongly affected by the stability of the capsules characterized by the stability index. The experiments conducted proved that the stability index is a valid criterion for explaining and correlating data on the capsule motion and the capsule density uniformity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.638-641
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• 2012

Optimal net residual dispersion (NRD) and effective launching power range of optical transmission links with random distribution of single mode fiber (SMF) length and residual dispersion per span (RDPS) required to flexibly design of optical links in dispersion management (DM) technique for compensating the distorted 960 Gbps optical signals due to interaction of group velocoty dispersion (GVD) and optical nonlinear effects are induced.