• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1286-1299
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• 1991

In this paper we present a multiple capture model for common spreading code CDMA packet radio systems with star topology. Basic equations for the collision free, header detection. and multiple capture probabilities are derived at the central receiver. Link performances. including the average number of packet captures, allowable number of simultaneous transmission, and system throughput are theoretically evaluated for a hybrid system. combining envelope header detection and differential data detection, Using the Block Oriented Systems Simulator(BOSS), simulations were carried out for the central receivers with envelope or differential geader detection, It is shown that for a threshold approx-imation to the probability of data packet success, the mulyiple capture model significantly improves system throughput.

• Journal of the Optical Society of Korea
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• v.11 no.2
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• pp.59-62
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• 2007

In this paper, we introduce a reliable, scalable, and cost-effective switchless wavelength division multiplexing (WDM) network based on a quality-of-service supporting reservation-based medium access control (MAC) protocol. The protocol not only provides both packet and circuit switching but also supports multicasting. The network efficiency is significantly increased by spatially reusing wavelengths and exploiting multiple free spectral ranges (FSRs) of arrayed waveguide grating (AWG) employed in the architecture. We have demonstrated the feasibility of this architecture by simulating in $Optsim^{TM}$.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.38.2-38.2
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• 2020

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on a Gpc scale while achieving a resolution of 1 kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. Inside the simulation box. we zoom-in on a high-resolution cuboid region with a volume of 1049 × 114 × 114 Mpc3. The subgrid physics chosen to model galaxy formation includes radiative heating/cooling, reionization, star formation, supernova feedback, chemical evolution tracking the enrichment of oxygen and iron, the growth of supermassive black holes and feedback from active galactic nuclei (AGN) in the form of a dual jet-heating mode. For this simulation we implemented a hybrid MPI-OpenMP version of the RAMSES code, specifically targeted for modern many-core many thread parallel architectures. For the post-processing, we extended the Friends-of-Friend (FoF) algorithm and developed a new galaxy finder to analyse the large outputs of HR5. The simulation successfully reproduces many observations, such as the cosmic star formation history, connectivity of galaxy distribution and stellar mass functions. The simulation also indicates that hydrodynamical effects on small scales impact galaxy clustering up to very large scales near and beyond the baryonic acoustic oscillation (BAO) scale. Hence, caution should be taken when using that scale as a cosmic standard ruler: one needs to carefully understand the corresponding biases. The simulation is expected to be an invaluable asset for the interpretation of upcoming deep surveys of the Universe.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1253-1256
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• 2003

HFC(Hybrid Fiber Coax)망은 광케이블 구간과 동축케이블 구간으로 나뉘어져 있으며 광케이블 구간은 성형(Star)구조를 가지며 동축케이블 전송구간은 수지분기형(Tree and Branch)구조로 되어있다. HFC망의 상향채널은 가입자에서 헤드앤드로 데이터 전송 시 500가입자 이상이 공유하기 때문에 이를 제어하기 위한 매체접근제어(Medium Access Control)프로토콜이 필요하다. 특히, 음성, 비디오 그리고 데이터와 같은 트래픽의 QoS(Quality of Service)를 만족시키기 위해서는 서비스별로 우선 순위를 고려한 충돌해결알고리즘이 요구되어진다. 그러므로, 본 논문에서는 기존 알고리즘의 문제점을 분석하여 트래픽 특성에 따라 우선순위를 제공하는 충돌해결알고리즘을 제안하였다.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.645-648
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• 2009

본 논문에서는 신재생에너지 활용을 위한 휴대용 하이브리드 태양광 풍력 발전 시스템을 제안한다. 제안하는 태양광 풍력 복합 발전 시스템을 상용전기와 연계하여 사용할 경우를 고려하여 중대형 풍력 발전 시스템용 인버터와는 다른 특성이 요구되는 소형풍력 발전 시스템용 인버터와 독립형으로의 사용을 위해 축전지 충방전 컨트롤러를 개발한다. 20W의 Solar Power, 50W의 Wind Power, 1개의 Radio-recorder, 2개의 DC 7W/9W lamp. 축전지 Controller, 24H/40AH Maintenance-free battery 사양을 갖는 발전 시스템을 제작하고 필드 테스트를 통하여 성능을 검증한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1252-1260
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• 1999

The HFC network has a architecture of a star topology in fiber optic trunks, and tree and branch topology is used in the part of coaxial cable. It is well known that the HFC upstream channel is noisy. Ingress, common mode distortion and impulse noise exist in the upstream channel. In order to provide Quality of Service(QoS) to users with real-time data such as voice, video and interactive services, the evolving IEEE 802.14 standard for HFC networks must include an effective priority scheme. The scheme separates and resolves collisions between stations in a priority order. It is important to simulate protocols under a practical environment. The proposed algorithm in this paper is simulated with the assumption that the collision detector made certain mistake due to noises. Simulation results show that the proposed algorithm is more efficient than existing tree-based algorithm under practical environment.

• The Journal of Society for e-Business Studies
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• v.12 no.4
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• pp.99-125
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• 2007

Recently, as the development of Ubiquitous Smart Space (USS) such as U-City is proliferating, preparing a development methodology dedicated to USS characteristics has become one of the crucial issues to increase the productivity of the USS projects. However, since the legacy development methodologies such as traditional UML do not consider the critical components of ubiquitous computing space such as context-awareness, service oriented architecture and multi-agent communication, they are not optimized for USS analysis and design. Hence, the purpose of this paper is to propose a USS-sophisticated development methodology. To do so, a hybrid approach, BPR-USS for space reengineering and UML-USS by amending UML with corresponding toolkit based on StarUML has been implemented. To show the feasibility of the approach described in this paper, an illustrative example with an actual USS development project for a multiplex space in Seoul is shown.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.57.2-57.2
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• 2018

We present the preliminary result from our KVN single-dish observations of the MALATANG sample. The MALATANG (Mapping the dense molecular gas in the strongest star-forming Galaxies) is one of the JCMT legacy surveys on the nearest 23 IR-brightest galaxies beyond the Local Group. The goal of the MALATANG survey is to map the sample in the dense gas tracers (HCN and HCO+J=4-3), and probe the relationships between the dense molecular gas and star formation activities. As a complementary study, we recently launched a KVN/KaVA program on the same sample, in order to measure their flux densities and parsec-scale jet/outflows in the millimeter regime, which will be greatly useful in understanding the initial conditions of the feedback process. In this work, we present the preliminary result from our pilot KVN single-dish program on a sub-sample, which will be used to select the future VLBI imaging study under plan. We investigate the KVN spectral energy distributions (SED) of the sample as a function of the power source of the luminous IR brightness of each target (starburst? AGN? or hybrid?). We also discuss the technical challenges that we experienced during our KVN observations due to the large size of the sample in the sky.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.651-654
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• 2011

Cymbidium 'Orange Bowl' (Lucky Rainbow 'Randevous' ${\times}$ 'Eastern Star') was developed from a cross between hybrids at the National Institute of Horticultural & Herbal Science, Rural Development Administration in 2006. A cross was made between the pink colored flower C. Lucky Rainbow 'Randevous' as maternal line and pure yellow colored flower, C. 'Eastern Star' as paternal line in 1995. The seed germination, cultivation, selection, and characteristic trials were conducted from 1996 to 2006. The line was named as Wongyo F1-18 and phenotype was characterized in 2006 as a new 'Orange Bowl'. The 'Orange Bowl' has having light yellow basal color (RHS, YO21D) and orange line (RHS, OR30B) on both of sepal and petal with red lip (RHS, OR30B). 'Orange Bowl' has about 10.9 flowers per flower stalk and flower size of 7.4 cm. General appearance of the petals and sepals is slightly incurved shape. The plant size is intermediate having erect peduncle. Blooming is started from the late of January (mid winter) under optimal culture condition. Leaf attitude and twisting is half- erect and very weak respectively. This hybrid has attractive floral arrangement, long flower stalk (71.8 cm) and vigorous growth. We expect that 'Orange bowl' has a great potential for exporting to Chinese market.

• Journal of The Korean Society of Grassland and Forage Science
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• v.32 no.1
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• pp.29-38
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• 2012

This study was carried out to compare the agronomic characteristics, forage yield, and feed value of nine sorghum ${\times}$ sudangrass hybrids at paddy field cultivation. The nine recommended sorghum ${\times}$ sudangrass hybrids used in this study were P877F, Cow pow, Turbo gold, Maxi graze, Jumbo, G7, Sweet home, Honey chew BMR and Green star. Plant height, leaf number, stem diameter, and stem hardness were higher in Jumbo than other varieties (P<0.01). Sugar content (brix) was higher in order of P877F > Sweet home > maxi graze > Green star > Cow pow > G7 (P<0.01). Fresh (86,199kg/ha) and dry matter yield (16,206 kg/ha) of Jumbo were higher than other varieties (P<0.01). Crude protein was the highest in Maxi graze (6.5%), but crude fat was the highest in Honey chew BMR as 2.1% (P<0.01). NDF and ADF of Jumbo and G7 were higher than other varieties (P<0.01). TDN was higher in order of Maxi graze > Sweet home > P877F > Honey chew BMR > Green star, but no significant differences were found among the varieties. Minerals were the highest in Cow pow (15,020.5 mg/kg), and Sweet home (6,222.6 mg/kg) was the lowest as compared to other varieties (P<0.01). Total amino acids were higher in order of Maxi graze > Sweet home > Turbo gold > Honey chew BMR > Jumbo (P<0.01). Crude protein yield and crude fat yield were the highest in Turbo gold (814.6 kg/ha) and Honey chew BMR (309.8kg/ha), respectively (P<0.01). Mineral yield was the highest in Cow pow as 207.6 kg/ha (P<0.01). Amino acid yield (592.2 kg/ha) and TDN yield (10,194 kg/ha) were the highest in Sweet home. Based on the above results, sorghum ${\times}$ sudangrass hybrid varieties should be selected on the basis of the purpose of use. Because, each varieties showed various growth characteristics and nutrition yield (protein, fat, mineral, amino acid, TDN).