• Animal Systematics, Evolution and Diversity
• /
• 제21권1호
• /
• pp.45-56
• /
• 2005

하수처리장과 계곡의 웅덩이에서 채집된 3종의 Gastrostyla 섬모충류가 Gastrostyla minima Hemberger, 1985, G. steinii Engelmann. 1862 그리고 G. setifera (Engelmann, 1862)로 동정되었다. 기재는 생체표본, protargol 염색표본 관찰과 관찰된 표본의 형태통계에 기초하여 기술하였다 이 종들의 형태적 변이는 측정된 형질의 기술통계처리로 분석되었다. 이들 3종은 한국에서 처음으로 기록되는 종으로 아래의 식별형질로 구분된다 G. minima는 일반적으로 2개의 대핵에 구형의 소핵이 하나씩 있고, 하나의 후방구복극모 (poVC, postoral ventral cirri)와 연속적인 복극모섬모열 (VCR, ventral cirral row), 5개의 후방극모 (TC), 6개의 등쪽섬모열에서 네 번째 섬모열은 끊어져 있고 cortical granules들을 가진다. G. steinii는 4개의 대핵과 3-5개의 소핵을 가지고, 하나의 후방구복극모(poVC)와 연속되지 않는 복극모섬모열 , 4개의 후방극모, 6개의 등쪽섬모열을 가지며 cortical granules들이 없다. G. setifera는 2개의 대핵에 구형의 소핵이 하나씩 있고, 두 그룹으로 뚜렷하게 나누어진 5개의 후방극모가 있으며, 6개의 등쪽섬모열, 두개의 후방구복극모와 연속되지 않는 복극모섬모열을 가지며 cortical granules은 없다.

• Journal of Computing Science and Engineering
• /
• 제7권3호
• /
• pp.168-176
• /
• 2013

Long-term evolution (LTE) is emerging as a major candidate for 4G cellular networks to satisfy the increasing demands for mobile broadband services, particularly multimedia delivery. Multiple-input multiple-output (MIMO) technology combined with orthogonal frequency division multiple access and more efficient modulation/coding schemes (MCS) are key physical layer technologies in LTE networks. However, in order to fully utilize the benefits of the advances in physical layer technologies, the MIMO configuration and MCS need to be dynamically adjusted to derive the promised gains of 4G at the application level. This paper provides a performance evaluation of video traffic with variations in the physical layer transmission parameters to suit the varying channel conditions. A quantitative analysis is provided using the perceived video quality as a video quality measure (evaluated using no-reference blocking and blurring metrics), as well as transmission delay. Experiments are performed to measure the performance with changes in modulation and code rates in poor and good channel conditions. We discuss how an adaptive scheme can optimize the performance over a varying channel.

• 대한수학회지
• /
• 제49권3호
• /
• pp.585-604
• /
• 2012

In this paper we consider the evolution of the rolling stone with a rotationally symmetric nonconvex compact initial surface ${\Sigma}_0$ under the Gauss curvature flow. Let $X:S^n{\times}[0,\;{\infty}){\rightarrow}\mathbb{R}^{n+1}$ be the embeddings of the sphere in $\mathbb{R}^{n+1}$ such that $\Sigma(t)=X(S^n,t)$ is the surface at time t and ${\Sigma}(0)={\Sigma}_0$. As a consequence the parabolic equation describing the motion of the hypersurface becomes degenerate on the interface separating the nonconvex part from the strictly convex side, since one of the curvature will be zero on the interface. By expressing the strictly convex part of the surface near the interface as a graph of a function $z=f(r,t)$ and the non-convex part of the surface near the interface as a graph of a function $z={\varphi}(r)$, we show that if at time $t=0$, $g=\frac{1}{n}f^{n-1}_{r}$ vanishes linearly at the interface, the $g(r,t)$ will become smooth up to the interface for long time before focusing.

• Journal of Communications and Networks
• /
• 제2권1호
• /
• pp.35-45
• /
• 2000

this paper presents the concept of "mobile ATM', a proposal for third-generation (3G) mobile communication network infrastructure capable of supporting flexible evolution of radio technologies from today's cellular and data services towards future wireless multimedia services. Mobile ATM provides generic mobility management and QoS-based transport capabilities suitable for integration of multiple radio access technologies including cellular voice. wireless data, and future broadband wireless services. The architecture of a mobile ATM network is outlined in terms of the newly-defined "W-UNI" interface at the radio link and "M-UNI"and "M-UNI" interface which supports unified access for WATM and non-ATM mobile terminals through corresponding interworking functions (IWF) is explained. leading to an understanding of how different radio access technologies are supported by the same ATM-based core network infrastructure. Generic mechanisms for handoff and location management within the core mobile network are discussed. and related protocol extensions over the "W-UNI" and "M-UNI/NNI"interfaces are proposed. the issue of "crossover switch (COS)" selection in mobile ATM is considered, and a unified handoff signaling syntax which supports flexibility in COS selection is described. Typical signaling sequences for call connection and handoff using the proposed protocols are outlined. Experimental results form a proof-of-concept mobile ATM network prototype are presented in conclusion.

• 대한화학회지
• /
• 제55권4호
• /
• pp.680-684
• /
• 2011

Balanites Aegyptiaca 씨기름으로부터 바이오 디젤유를 생산하고 기름 품질 및 생분해성을 조사하였다. 비중, 밀도와 인화점은 각기 0.897, 0.89 g/$cm^3$ and $163^{\circ}C$이었다. 이 바이오 디젤유는 $D_2$ 디젤유(27.02%, 27.33%)에 비해 월등하게 82.58%, 86.98% 생분해 되었다.

• 천문학회지
• /
• 제32권1호
• /
• pp.7-16
• /
• 1999

Open clusters are useful tools to investigate the structure and evolution of the Galactic disk. We have started a long-term project to obtain UBVI CCD photometry of open clusters which were little studied before, using the Doyak 1.8 m telescope of Bohyunsan Optical Astronomy Observatory in Korea. The primary goals of this project are (1) to make a catalog of UBVI photometry of open clusters, (2) to make an atlas of open clusters, and (3) to survey and monitor variable stars in open clusters. Here we describe this project and report the first results based on preliminary analysis of the data on four open clusters in the survey sample: Be 14, Cr 74, Biu 9, and NGC 2355. Isochrone fitting of the color-magnitude diagrams of the clusters shows that all of them are intermediate age to old (0.3-1.6 Gyrs) open clusters with moderate metallicity.

• Advances in aircraft and spacecraft science
• /
• 제5권3호
• /
• pp.349-362
• /
• 2018

A non-linear numerical simulation technique for predicting the unsteady performances of an airbreathing engine is developed. The study focuses on the simulation of integrated propulsion systems, where a closer coupling is needed between the airframe and the engine dynamics. In fact, the solution of the fully unsteady flow governing equations, rather than a lumped volume gas dynamics discretization, is essential for modeling the coupling between aero-servoelastic modes and engine dynamics in highly integrated propulsion systems. This consideration holds for any propulsion system when a full separation between the fluid dynamic time-scale and engine transient cannot be appreciated, as in the case of flow instabilities (e.g., rotating stall, surge, inlet unstart), or in case of sudden external perturbations (e.g., gas ingestion). Simulations of the coupling between external and internal flow are performed. The flow around the nacelle and inside the engine ducts (i.e., air intakes, nozzles) is solved by CFD computations, whereas the flow evolution through compressor and turbine bladings is simulated by actuator disks. Shaft work balance and rotor dynamics are deduced from the estimated torque on each turbine/compressor blade row.

• 디지털융복합연구
• /
• 제20권3호
• /
• pp.63-68
• /
• 2022

5G 서비스 등장한 후 우리의 생활 방식을 크게 변화시켰다. 특히 스마트폰과 Long Term Evolution을 통한 네트워크 서비스의 확산은 사람과 사람 사이에 음성, 문자통신에 한정되었던 기존 이동통신 방식을 완전히 바꾸었으며, 사용자와 기업 활동의 모든 측면에서 혁신적 서비스들이 등장하게 되었다. 본 연구는 5G 서비스의 사용자 사회적 특성과 사용자가 5G 서비스의 사용의도의 관계를 검증하였다. 독립변수(사회적 실재감, 주관적 규범)들과 매개변수(지각된 유용성) 및 종속변수(사용의도) 간의 관계를 규명하고, 측정변수 간의 영향관계에서 지각된 유용성의 매개효과를 검증하였다. 본 연구에서는 5G 서비스의 사용자를 대상으로 설문조사를 진행하여 실증분석을 위한 데이터를 수집하였다. 연구결과, 5G 서비스의 사용자 사회적인 요인에서 사회적 실재감, 주관적 규범이 사용자들의 사용의도를 높일 수 있는 적합한 변수임을 확인하였으며, 지각된 유용성의 매개효과도 있는 것으로 검증되었다. 본 연구는 실증분석을 통해 5G 서비스의 지속 가능하고 안전한 발전을 위한 시사점을 제시하였고, 향후 관련 연구의 방향에 대해서도 제시하였다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제2권3호
• /
• pp.119-126
• /
• 2010

The response of ship roll oscillation under random ice impulsive loads modeled by Poisson arrival process is very important in studying the safety of ships navigation in cold regions. Under both external and parametric random excitations the evolution of the probability density function of roll motion is evaluated using the path integral (PI) approach. The PI method relies on the Chapman-Kolmogorov equation, which governs the response transition probability density functions at two close intervals of time. Once the response probability density function at an early close time is specified, its value at later close time can be evaluated. The PI method is first demonstrated via simple dynamical models and then applied for ship roll dynamics under random impulsive white noise excitation.

• Journal of Astronomy and Space Sciences
• /
• 제20권3호
• /
• pp.175-184
• /
• 2003

To investigate the SEDs of galaxies considering the dust extinction processes in the galactic disks, we present the population synthesis models for normal galaxies with dusty disks. We use PEGASE (Fioc & Rocca-Volmerange 1997) to model them with standard input parameters for stars and new dust parameters. We find that the model results are strongly dependent on the dust parameters as well as other parameters (e.g. star formation history). We compare the model results with the observations and discuss about the possible explanations. We find that the dust opacity functions derived from studies of asymptotic giant branch stars are useful for modeling a galaxy with a dusty disk.