• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.734-736
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• 1998

In this paper we obtain a discrete mathmatical model of a Gas turbine control system from experimental data. we find appropriate input signal and parameter estimation algorithm for identification of the gas turbine control system. Under these conditions experimental data are collected from real system and parameters are estimated by the recursive least square algorithm. The computer simulation results show that the proposed experimental procedure is appropriate for the identification of the gas turbine control system. The model validation is excuted by real data from the Gunsan Gas Turbine Power Plant.

• 한국응용곤충학회지
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• 제22권1호
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• pp.34-41
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• 1983

The twelve species of Scolytidae and six species of Platypodidae were recognized from imported logs at Incheon, Gunsan and Busan ports. One species, Hypothenemus hampei (Ferrari) of Scolytidae was identified from coffee bean. These species were not reported before from imported logs and seeds. Scolytidae Platypodidae Scolytus frontalis Blandford Crossotarsus nitens Chapuis Hylurgopsl gabratus Zetterstedt P. lepidus Chapuis Gnathotricus sulcatus (Leconte) Diapus quinquespinatus Chapuis Hypothenemus hampei (Ferrari) Genyocerus abdominalis Schedi Ips concinuus (Mannerheim) G. compactus Schedl Poecilips subcribrosus (Blandford) G. sexporus (Schedl) xyleborus agnatus Eggers X. cognatus Blandford X. emarginatus Eichnoff X. mascarensis Eichhoff X. pseudomajor Schedl X. pseudopilifer Schedl.

• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1515-1518
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• 2007

A preparative method of Me2SCuX (X = Cl, Br) via one-pot reaction was developed from common chemicals such as benzyl halide, DMSO, and Cu(0). In the reaction mixture small molecules such as methyl halide and dimethyl sulfide etc. were efficiently generated in situ, resulting in the formation of Me2SCuX. Oxidation of Cu(0) in reacting with both benzyl halide (starting material) and methyl halide (in situ generated product) to Cu(I) followed by complexing with dimethyl sulfide (in situ generated product) could explain the formation of Me2SCuX. In particular we found out that heterogeneous reaction of Me2SCuX and arenediazonium tetrafluoroborate in acetonitrile was so effective to afford corresponding bromoaromatics under mild conditions.

• Journal of Magnetics
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• 제14권2호
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• pp.86-89
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• 2009

Structural and magnetic properties of polycrystalline $CaFe_2O_4$ prepared by the solid state reaction method were studied using powder X-ray diffraction (XRD) and $M{\ddot{o}}ssbauer$ spectroscopy. The structure of $CaFe_2O_4$ belongs to an orthorhombic system (space group: Pnma) with the lattice parameters $a=9.2373\;{\AA}$, $b=3.0237\;{\AA}$, and $c=10.7124\;{\AA}$. Results of structural refinement indicate, however, that there are two slightly different iron sites in the sample. The $M{\ddot{o}}ssbauer$ spectrum at 4.2 K shows a hyperfine sextet with a hyperfine magnetic field and an isomer shift of 47.3 T and 0.36 mm/s, respectively. An examination of the spectrum revealed that the line widths of the spectral lines were not uniform. The degree of asymmetric line broadening decreases with increasing temperature, suggesting that the difference in the degree of crystalline distortions between two $FeO_6$ octahedra is eliminated as the temperature rises.

• ETRI Journal
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• 제29권1호
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• pp.107-109
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• 2007

In location-based services, most trigger technologies have been implemented on the server side by periodically requesting the locations of mobile phones from mobile network servers. However, bottlenecks and communication interruptions occur when the servers are overloaded by trigger requests. In this letter, we propose a new multilevel location trigger specification which distributes the event detecting role to mobile phones and redesigns the location triggering into a multilevel step. Our suggested location trigger specification can reduce bottlenecks caused by triggers in a mobile core network and reduce power consumption caused by embedded GPS devices in mobile phones.

• Journal of Magnetics
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• 제12권3호
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• pp.108-112
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• 2007

Nature of phase transition in $LaVO_3$ has been studied using X-ray diffraction, SQUID magnetometer, and $M\"{o}ssbauer$ spectroscopy with 1% of $^{57}Fe$ doped sample. The crystal structure was orthorhombic with space group Pnma. Antiferromagnetic phase transition temperature $T_N$ was 140K, below which a weak ferromagnetic trace has been found. $M\"{o}ssbauer$ spectra below $T_N$ were single set of hyperfine sextet, which enabled us to discard the possibility of two inequivalent magnetic sites or uncompensated antiferromagnetism. Hyperfine magnetic field abruptly disappeared as low as about 90K, much below $T_N$.

• 한국항만경제학회지
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• 제19권2호
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• pp.33-53
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• 2003

The purpose of this paper is to investigate the effectiveness of port investemnt which is one of the important elements for measuring the port efficiency by using congestion approach of DEA(Data Envelopment Analysis). Congestion is said to be present when increases in inputs result in input reductions. Congestion approach takes the forms of weak input disposability and strong input disposability. Empirical analysis by using congestion approach in this paper identified inefficiencies in the inputs including port investment, and indicated inefficient ports like the ports of Sokcho, Gunsan, Pohang, and Seoguipo which shows the large amount of slacks with congestion especially in terms of port investment. Therefore these ports should examine the reason about the inefficiency of port investment. The main policy implication based on the findings of this study is that The Ministry of Maritime Affairs & fisheries in Korea should introduce congestion approach when the amount of port investment to each port is decided.

• 한국항해항만학회지
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• 제37권2호
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• pp.187-193
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• 2013

In this prolonged economic recession, the countries in Northeast Asia play a crucial role in the global market and the relationship between Korea and China gets more attention due to its significant achievement during the past 20 years after the establishment of diplomatic ties in 1992. In this regards, this study presents general overview of Korea-China Car Ferry Route and evaluates the efficiency level of each operating route using DEA model. Incheon-Yingkou, Incheon-Lianyungang, Pyeong Taek-Lianyungang are analyzed as efficent routes, while from the view point of passenger efficiency, 4 routes i.e, Incheon-Dalian, Incheon-Dandong, Pyeong Taek- Weihai, Gunsan-Shidao are also noted as efficient routes. Consequently, other inefficient routes can benchmark these efficient routes by increasing cargo volume and passengers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.332-334
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• 1994

This paper proposes a robust active noise control (ANC) system. The system constructs filter with a standard model. An adaptive litter, connected to the system in parallel, compensates the modeling error. When the adaptive filter does not work, the proposed system is robust while the conventional system loses the noise control capability. But proposed ANC system shows that the performance is comparable with that of the conventional ANC system under normal conditions.

• Mycobiology
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• 제45권4호
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• pp.353-361
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• 2017

During a survey of fungal diversity of the order Hypocreales in Korea, two Acremonium isolates, CNUFC-1YSRS2-4 and CNUFC-GSNPF3-1, were isolated from soils collected on a bank of the Yeongsan River, Naju, and in a forest on the Mt. Daegak located on Sinsi Island, Gunsan, South Korea, respectively. Based on the morphological characteristics and sequence analysis of the internal transcribed spacer and D1/D2 domains of 28S ribosomal DNA, the isolates CNUFC-1YSRS2-4 and CNUFC-GSNPF3-1 were identified as A. variecolor and A. persicinum, respectively. These 2 species represent novel Hypocreales isolates in Korea.