• 한국해안해양공학회지
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• 제7권4호
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• pp.289-304
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• 1995

북태평양에서 선택한 조석 정점에서 상대 해수면의 시계열 자료와 하와이 제도에서 해안선 변화의 항공 사진을 분석하였다. 대부분의 정점에서 해면의 장기적 상승 추이는 +1 내지 +5 mm/yr의 범위를 보이는데, 주로 지구 온난화 및 지질학적 판(plate)의 이동에 의해 나타나고 있다. 해면의 연변화 및 수년 주기의 변화는 각각 태양 복사의 연변화에 의한 표층수의 팽창 및 수축과, ENSO 주기와 관계된 대기-해양의 상호작용으로부터 기인한다. 이러한 세 가지의 다른 시간 규모로 발생하는 해면변화(장기적 해면상승 추이, 연변화, 수년주기 변화)가 장기적으로 이안 퇴적물 수송의 결과로서 나타나는 해안선 변화에 어떻게 정량적으로 기여하는지 추정하는 가설이 제시된다.

• 한국대기환경학회지
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• 제12권2호
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• pp.167-177
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• 1996

To investigate the source-receptor relationships aerosol model has been used to simulate the distribution behavior of the yellow sand. Data for meteorological fields were obtained by Meso-scale Analysis and Prediction Model System/Seoul National University (MAPMS/SNU) for five days (10-14 April 1988). To obtain the distributions of concentration of yellow sand,the aerosol model has been modified to allow quantifications of relative concentration distributions of yellow sand. Source regions of yellow sand were delineated by soil maps of China and emission rate as a function of wind stress(Westphal et al., 1987). Using 3-dimensional wind fields the backward trajectories from 3 receptor grids at the layer of .sigma. =0.95, 0.9, 0.85, 0.8 were calculated. In order to facilitate quantitative assessment of source-receptor relationships, it was assumed that the perturbations in along-trajectory and cross-trajectory proceed linearly with time, in accord with Gaussian distribution characteristics. On the basis of this assumption, the probability fields were calculated from every grid point with source strength 1. Using these probability fields and emission retes, the potential contributions of upstream sources along the trajectories were estimated. The results of this study indicate that the application of trajectory modeling is useful in investigating the quantitative relationship between source and receptor regions.

• Asian Journal of Atmospheric Environment
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• 제5권3호
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• pp.172-180
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• 2011

The transfer of microorganisms is important process for ecosystems. Microorganisms in dryland can transport itself to wetland through atmospheric diffusion, but only few papers reported about the atmospheric bioaerosol present over dryland. We carried out the direct sampling using a tethered balloon over Dunhuang City, China's northwestern dryland. Bioaerosols were collected using a tethered balloon with a bioaerosol collector at 820 m above the ground (1,960 m above the sea level) around noon on August 17, 2007. The bioaerosols were cultured after the collection at Dunhuang Meteorological observatory. Two strains of molds were isolated using the Nutrient agar medium. About 400-bp 18S rRNA partial sequences were amplified by PCR and determined afterwards. The results of a homology search by 18S rRNA sequences of isolates in DNA databases (GenBank, DDBJ, and EMBL) and an observation of the form revealed that two bioaerosols in the convective mixed layer over Dunhuang City were Cladosporium sp. and Aspergillus sp.

• 인터넷정보학회논문지
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• 제5권5호
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• pp.39-48
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• 2004

RTP (real-time transport protocol)는 인터넷상에서 실시간 멀티미디어 트래픽을 전송하기 위한 유력한 프로토콜로서 간주되고 있다. 망내에서 실시간 멀티미디어 트래픽을 제어하고 관리하기 위하여는 망 관리자가 망을 통하여 전달되는 실시간 멀티미디어 트래픽들을 감시하고 분석해내는 것이 필요하지만, 기존의 트래픽 분석 도구들은 RTP 패킷들을 비실시간 뿐만 아니라 실시간으로도 정확히 분류, 분석해 내지 못하고 있다. 본 논문에서는 인터넷에서 RTP를 사용하는 실시간 멀티미디어 트래픽을 실시간으로 분류해 내기 위한 방법을 제안한다. 한국전산원의 국제망 연동을 위한 게이트웨이 라우터에서 직접 수집한 데이터를 사용하여, 제안 방법의 정확성과 신속성을 보였다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2003년도 한국우주과학회보 제12권2호
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• pp.40-40
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• 2003

When the magnetotail is disturbed by an impulsive input such as the substorm onset, compressional magnetohydrodynamic (MHD) waves play an important role in delivering perturbed energy and exciting various wave modes and currents. The plasmasheet, in which relatively hot plasmas exist, is surrounded by relatively cold plasmas at the plasma sheet boundary layer (PSBL) and the equatorial plasmasphere. Since the Alfven speed significantly varies near these regions, the compressional waves are expected to undergo mode conversion by inhomogeneity at the boundary between cold and hot plasma regions. We investigate how the initial compressional MHD wave energy is reflected, transmitted, and absorbed across that boundary by adopting the invariant imbedding method (IIM) which gives the exact reflection, transmission, and absorption coefficients without any theoretical approximations for given frequencies and wave numbers. The IIM method is very useful in quantifying the reflection and transmission of compressional waves in the sense that we can calculate how much fast mode wave energy is delievered into shear Alfven waves or field-aligned currents. Our results show that strongly localized absorption occurs at the boundary region. This feature suggests that localized field-aligned currents can be impulsively excited at such boundary regions by any compressional disturbances, which is highly associated with impulsive auroral brightening at the substorm onset. We compare our results with previous studies in cold inhomogeneous plasmas.

• Environmental Analysis Health and Toxicology
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• 제28권
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• pp.6.1-6.7
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• 2013

Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.

• 한국통신학회논문지
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• 제17권4호
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• pp.336-345
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• 1992

본 논문에서는 상호 접속된 토큰링 근거리 통신망 환경하에서의 단말간 전송 효율 및 지연 현상에 대한 성능 평가를 행하였다. 상호 접속된 시스템은 단일 및 자중 체인 폐쇄 큐잉 망으로 모델링 하였다. 성능 평가를 위해 평균 값 해석 기법에 기초를 둔 반복 해법 알고리즘을 제안하였다. 단말간 전송 모델의 성능을 평가한 결과 브릿지로 상호 접속한 근거리 통신망 환경하에서 윈도우 크기, 상호 접속 링크 용량, 각 큐의 서비스 시간 등을 망의 구성에 따라 적절히 유지하여야 최적의 전송 효율과 지연을 얻을 수 있음이 발견되었다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (D)
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• pp.230-235
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• 2008

현재 대부분의 무선랜은 유선 분산 시스템을 통하여 백본에 연결되어 있다. 그러나 지역회담이나 재해재난 지역 그리고 군사용등은 유선 백본을 사용할 수 없다. 따라서 무선으로 액세스 포인트를 연결하여 일시적으로 네트워크 서비스를 원하는 곳이나 케이블을 연결하기 힘든 지역에서 빠르고 쉽게 네트워크 구성을 제공하기 위한 무선 메쉬 네트워크의 요구가 늘어나고 있다. 본 논문에서는 이러한 무선 메쉬 네트워크의 기반 기술인 무선 분산 시스템 환경에서 TCP와 UDP 프로토콜의 성능에 대하여 연구하였다. 시스템 성능 측정은 IEEE 802.11g 인터페이스를 가지고 있는 액세스 포인트에서 체인 토폴로지를 기본으로 측정되어졌고, 홉수와 트래픽 종류 그리고 트래픽 흐름의 방향에 따라 수율(throughput)과 전송시간(transaction time) 그리고 전송실패율(loss rate) 등을 비교 분석하였다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.222-222
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• 1999

From extensive measurements of the resistance and the dynamic resistance as functions of magnetic field and temperature, we find that the transport in the insulating state beyond the superconductor-insulator (S-I) transition is dominated by bosons(Cooper pairs and/or vortices) and cannot be described by the theory of the fermionic insulating phase. The maximum of the magnetoresistance at B = B$_m$ and the following negative slope in R(B) with increasing field can be explained by the crossover from the "Bose-glass" to the "Fermi-glass" phase as suggested by Paalanen, Hebard, and Ruel. The zero bias peak in dv/dl for biases below the characteristic voltage V$_c$ (or current $I_c$), gives a clue for the assumption of the "dirty boson" model which states that the insulating state above the critical magnetic field is the phase where Cooper pairs are localized due to the Coulomb blockade with a nonvanishing order parameter. The shift to a lower value of the critical magnetic field by overlaying thin Au layer, which is known as a strong spin-orbit scatterer, also supports the bosonic nature of the S-I transition.

• Clinical and Experimental Reproductive Medicine
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• 제18권2호
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• pp.123-131
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• 1991

In order to study the growth and maturation of ovarian follicle, the localization and activity of alkaline phosphatase(ALPase) and adenosine triphosphatase(ATPase) of the granulosa cells and theca layer were examined according to the follicle size, the follicle state and the ovarian cyclic phase in pig. Theca interna of the small follicles was more heavyly localized with reaction product by the activites of ALPase and ATPase than that of the large follicles. It is assumed that, as the follicles proceed to growth and maturation, antrum formation is the result of the follicular fluid accumulation by means of active transport by the activities of ALPase and ATPase in theca interna. The activities of ALPase and ATPase in atretic follicles were higher than those of normal follicles. These results imply that the mechanisms of follicle maturation and atresia are different according to the phase of ovarian cycle.