• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 한국항해항만학회 2002년도 추계공동학술대회논문집
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• pp.169-174
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• 2002

It has known that the DCMP(Directionally Constrained Minimization of power)and the ZF(Zero Forcing) can improve the SINR performance of an array antenna system by using spatial signature of wireless channel. This paper analyzes performance of DCMP and ZF in multiple scattering environments. To obtain the spatial signature of wireless channel. bothe DOA(Directional of Arrival) and AS(Angular Spread) of the received signals were estimated by using ESPRIT. The performance of the DCMP and the ZF was analyzed theoretically. Through computer simulation, the SINR performance were evaluated.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• 제30권3호
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• pp.46-56
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• 1998

The objective of this study was to investigate the relationship between water vapor diffusion properties and the pore structure of paper. Gas-phase molecular diffusivity of water vapor through pores was determined based on the kinetic theory of gas. A mathematical model was derived to characterize the dimensional changes of the pore caused by the fiber-swelling mechanism. A modified-Fickean diffusion model was designed to simulate the water-vapor diffusion phenomena in porous paper web. Structural characterisocs of paper pores including the tortuosity and the shape factor was studied on a theoretical basis of Knudsen flow diffusion. Results are summarized as follows: 1. The theoretical water vapor diffusivity in gas-phase was 0.092$cm^2$ /min, 2. Porosity was inversely proportional to the degree of wet-swelling of paper, 3. Solid-phase water-diffusivity of fiber was 1.2 $ \times 10^{-5}cm^2/min$, 4. Modified diffusion model was fairly consistent to the experimental data (from part I), and 5. The Fickean pore tortuosity, ranging from 1,000 to 2,500, was in inverse proportion to the porosity of paper, and the Knudsen shape factor and length-angle factor for micro-pores in paper were 0.5~3.5 and about 340, respectively.

• Journal of the Korean Vacuum Society
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• 제17권2호
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• pp.122-129
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• 2008

Ferroelectric properties of the PMT-PT were also studied from the temperature dependence of hysteresis loops using a method slightly modified from Sawyer-Tower's. Dielectric, pyroelectric and piezoelectric properties of the ceramics in the system PMT-PT were investigated. The resulted densities of the PMT-PT ceramics system were greater than 97 % of the theoretical value. As observed SEM micrograph of the fracture surfaces of the PMT-PT ceramics system, the average grain sizes were increased about 3-5 ${\mu}m$ to 6-8 ${\mu}m$ with increasing sintering temperature. The specimens with PT<0.30 for PMT-PT solid solution system exhibited the dielectric and pyroelectric properties of a typical relaxor ferroelectrics. The composition with the maximum dielectric constant exhibits relatively superior pyroelectric and piezoelectric properties.

• Journal of Korean Society of Archives and Records Management
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• 제11권2호
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• pp.77-94
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• 2011

In this article, the author introduces the paradigm shift in archival studies that occurs in north America. Although the dominant paradigm in the archival studies-the positivism paradigm-greatly contributed to build modern archives in Europe and north America, during last decades, new ideas and technologies led the archival communities to re-identify their social roles and powers and to adopt new values of archives and archivist. This essay argues that this changes is essential to our future and we understand the nature of the changes from the broader interdisciplinary perspective of archives studies, information studies, and history.

• Research in Community and Public Health Nursing
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• 제28권2호
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• pp.129-143
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• 2017

Purpose: The purpose of this study is to explore factors which influence adoption, implementation and continued use of tele-healthcare systems. Methods: Qualitative research was conducted by in-depth interviews with 17 professionals from various fields of organizations involved in developing and implementing tele-healthcare systems. Data were analysed thematically, using a conceptual model of diffusion of innovations. Results: The system users were reacted positively to the 3 attributes out of 9 which decided the adoption of innovation. In addition, it is required to redesign the tele-health care system simpler and easier so that the system users can access to the system much more easily regardless of space and time limitations. From the design stage on an individual level, it is necessary to conduct detailed needs analysis and listen to users who are at the center of innovation diffusion. On an organizational level, it is necessary to actively prepare for possible problems during system implementation, educate the users and build communication channels continuously. Conclusion: This study has identified the factors affecting the innovation of tele-health care systems and contributed to the understanding of the operation of tele-health care systems by the diffusion of innovation theory in community health posts.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제16권12호
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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.

• Smart Media Journal
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• 제8권2호
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• pp.80-85
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• 2019

Generally, interlayer noise is measured in decibels (A) in terms of free field. In this paper, we propose a measurement method of interlayer vibration acceleration in the diffusion field perspective. The proposed method can represent a vibration-embodied formula similar to the sensitivity of earthquake intensity when the natural vibration of apartment house is measured by acceleration with its average value of $20mm/s^2$ represented by an the geometric progression of radix. Based on this theory, this paper proposes a method to show the optimal user experience (UX) by applying the interlayer vibration acceleration of the epicenter to the system of human - computer interaction (HCI).

• Corrosion Science and Technology
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• 제18권3호
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• pp.102-109
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• 2019

The hydrogen diffusion and trapping model with a numerical finite difference method (FDM) was modified and extended to accommodate $H_2S$ corrosion and scale forming processes of high-strength steel under tensile stress condition. The newly proposed diffusion model makes it possible to clearly understand combined effect of tensile stress and $H_2S$ corrosion process on hydrogen diffusion behaviors. The core concept of this theoretical approach is that overall diffusion behavior is separated into diffusion process through two respective layers: an outer sulfide scale and an inner steel matrix. Diffusion coefficient values determined by curve-fitting permeation data reported previously with the newly proposed diffusion model indicate that the application of tensile stress can contribute to continual increase in the diffusivity in the sulfide scale with a high density of defect. This suggests that the scale with a lower stability under the stress condition can be a key parameter to enhance hydrogen influx in the steel matrix. Consequently, resistance to hydrogen assisted cracking of the steel under tensile stress can be decreased significantly.

• Journal of Christian Education in Korea
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• 제63권
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• pp.39-64
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• 2020

COVID-19 is sweeping the world, and it is in crisis in all aspects of politics, economy, culture, and religion. As people experience the beginning and spread of COVID-19, wince and re-spread, the people are living in anxiety and depression. Because of the COVOD-19 crisis, Korean churches were unable to provide on-site worship, and online worship began, and churches that started on-site worship also performed online worship. In the case of church schools, the functions of fellowship and education were paralyzed and many are offering online Sunday service only. Many people eagerly want to go back to what it was before COVID-19, but it seems difficult because COVID-19 has become a global issue and a pandemic situation. We can't wait to get better out of this. In the COVID-19 crisis, the church was unable to properly handle the church's original work and to fully fulfill the mission of education. The response of many churches was to postpone the planned ministry to the second half of 2020. Now, we should try to set a new direction and prepare specifically to move in the new direction. With this perspective, this paper studied the direction of Christian education in the post COVID-19. Specifically, the theoretical basis of the direction of Christian education in the post COVID-19 was found in the theory of Agape's encounter, Catechesis theory, and diakonia theory, and specific directions were suggested according to these theories. Specifically, based on the theory of Agape's encounter, Christian education that emphasizes the encounter with the natural environment, Christian education that emphasizes the encounter among family members, Christian education that emphasizes the encounter among citizens of the world, and Christian education that emphasizes the encounter through online were presented. Based on the Catechesis theory, Christian education copping with the attack of heresy was presented. Finally, based on the diakonia theory, Christian education of service for society and Christian education of service based on data were presented.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.723-729
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• 2015

The moment analysis of cyclic adenosine monophosphate (cAMP) was performed using chromatograms that were obtained with the pulse input method from an octadecyl silica (ODS) high-performance liquid chromatography (HPLC) column. The general rate (GR) model was employed to calculate the first absolute moment and the second central moment. Three important coefficients for moment analysis, which are molecular diffusivity ($D_m$), external mass transfer coefficient ($k_f$), and intra-particle diffusivity ($D_e$), were estimated by the Wilke-Chang equation, Wilson-Geankoplis equation, and comparing van Deemter equation to theoretical plate number equation, respectively. Experiments were conducted by various conditions of flow rates, methanol volume ratio of the mobile phase, and solute concentration. After the moment analysis, results were organized by van Deemter plots. Also van Deemter coefficients were compared each other to effect $H_{ax}$, $H_f$, and $H_d$ on height equivalent to a theoretical plate (HETP, $H_{total}$). The value of intraparticle diffusion ($H_d$) was the primary factor which makes for HETP whereas external mass transfer ($H_f$) was disregardable factor.