• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9C
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• pp.955-963
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• 2005

In this paper, we consider the noncoherent code acquisition problem using sequential schemes. We show that the outputs of the noncoherent receiver approximately have a central chi-square distribution under the null hypothesis through simulations. Based on this observation, simplified acquisition schemes are obtained using the approximations of the Bessel function. The performance of the simplified and original schemes are compared in additive white Gaussian noise and slowly varying fading channels. Numerical results show that the simplified schemes have essentially the same performance as the original schemes.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.217-220
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• 2005

이 논문에서는 새로운 약신호 검파 기법을 얻어, 그 기법과 국소 최적 검파 기법을 바탕으로 순차 검파 방식을 이끌어낸다. 먼저, 새로운 약신호 검파 기법을 제안하고, 흥미로운 문턱값 성질을 몇가지 밝힌다. 제안한 순차 검파 방식에서 쓰는 두 문턱값은 어떤 단계에 이르면 크기가 바뀌어, 결정을 무한히 미룰 때도 있는 순차 확률비 검파 방식이 지닌 문제점을 풀어준다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.274-275
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• 2005

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.581-585
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• 2001

Alinite-Calciumchloroaluminate system clinker was synthesized from solid state waste. The raw materials were municipal incineration ash, sewage sludge, limestone and clay. ecocement was prepared by the mixing of synthesized clinker and optimum amount of gypsum and its hydrolysis characteristic was investigated. X-ray diffraction, conduction calorimeter and reflecting microscope were used to analyze structural and physical properties. The main phase of clinker were alinite, calcium chloroaluminate. $C_2$S, $C_3$S. From the results of hardening time, hydration reactivity of synthesized all samples was faster than that of ordinary portland cement.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2005.09a
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• pp.168-174
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.1016-1017
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• 2005

• Journal of Industrial Technology
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• v.11
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• pp.115-124
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• 1991

In this study, we design a position controller for two axis servo system. The position controller performs numerical control(NC)to DC or AC servo motor or step motor, and also has a digital input/output sequence capability. The control program composed of position and sequence command, which is called channel, is programmed easily and user-interactively. And it is interpreted and the straight line and arc position command is interpolated. We develop the Z80 microprocessor based system and the software with assembly and C language, and also PC based graphic simulator for the debugging and educational purposes.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.257-260
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• 2017

In this work, we present a facile one-pot synthesis of a multilayer-structured platy alumina/few-layer graphene nanocomposite by planetary milling and hot pressing. The sintered composites have electrical conductivity exhibiting percolation behavior (threshold ~ 0.75 vol.%), which is much lower than graphene oxide/ceramic composites (> 3.0 vol.%). The conductivity data are well-described by the percolation theory, and the fitted exponent values are estimated to be 1.65 and 0.93 for t and q, respectively. The t and q values show conduction mechanisms intermediate between 2D- and 3D, which originates from quantum tunneling between nearest neighbored graphenes.

• The Journal of Fisheries Business Administration
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• v.50 no.3
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• pp.43-57
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• 2019

Recreation specialization and consumptive orientation are two important constructs to understand anglers' attitudes and behaviors. Although theoretical explanations and previous studies in different countries addressed the relationships between the two constructs, limited support has been provided in a context of anglers in Korea. This study developed a conceptual model explaining the causal relationships between recreation specialization, anglers' preferences (activity-specific and activity-general) and consumptive orientation. An on-site survey was conducted to anglers in the city of Busan and Gyeongnam province in 2018. A total of 614 data were analyzed using Structural Equation Modeling The study results showed that recreation specialization positively and indirectly influenced consumptive orientation via anglers' activity-specific and activity-general preferences. Theoretical and practical implications are further discussed.

• Environmental Engineering Research
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• v.15 no.3
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• pp.157-161
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• 2010

Forest soils are often nitrogen-limited, and nitrogen input to forest soils can cause substantial changes in the structure and functions of a soil ecosystem. To determine the effects of nitrogen input on methane oxidation and the microbial enzyme activities, manipulation experiments were conducted using nitrogen addition to soil samples from Mt. Jumbong. Our findings suggested that the addition of nitrogen to the soil system of Mt. Jumbong did not affect the microbial enzyme activities. Conversely, the addition of nitrogen affected the rate of methane oxidation. Inorganic nitrogen in soils can inhibit methane oxidation via several mechanisms, such as substrate competition, toxic effects, and competition with other microbes, but the inhibitory effects are not always the same. In this research, seasonal changes were found to produce different inhibitory factors, and these different responses may be caused from differences in the methantrophic bacteria community structure.