• 한국환경과학회지
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• 제22권3호
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• pp.259-267
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• 2013

In this study, non-point source(NPS) contribution was investigated based on flow rates and water qualities of streams into the lake during rainfall events. Event mean concentration(EMC) and the pollution loads were calculated to establish a database for NPS control measurement in the survey area, and so on. The runoff characteristics of NPS were investigated and estimated on the basis of the ratio of an agricultural to forest area in the stream of sub-catch basin during rainfall events. Non-point source pollution loads were also calculated to establish a database for NPS control measure in the upstream lake Chinyang. At a rainfall event, BOD concentrations rise sharply at the early peak time of runoff, however, peaks of TSS concentration were observed at the similar time of peak flow. This was a phenomenon shown at the watersheds caused by forest and geological types. The discharged EMC range was 2.9-4.8 mg/L in terms of BOD. The discharged EMC range was 6.2-8.2 mg/L in terms of SS. The discharged EMCs of T-N and T-P were 1.4-2.5 mg/L and 0.059-0.233 mg/L, respectively. Total BOD loading rate through the 3 tributaries to the lake Chinyang was 1,136 kg/d during dry weather. The upper watershed area of the Nam-river dam in this study was divided into 14 catchment basins based on the Korean guideline for total maximum daily load(TMDL) of water quality pollutants. The higher the agricultural land-use ratio, the more NPS loading rate discharged, but the more occupied a forest area, the lower more NPS loading rate discharged. In an agricultural land-use area more than 20%, the increase of NPS loadings might be dramatically diffused by increasing the integrated complex-use like vinyl-house facilities and fertilizer use etc. according to the effective land-use utilization. The NPS loading rates were BOD 0.3 $kg/ha{\cdot}day$, SS 0.21 $kg/ha{\cdot}day$, TN 0.02 $kg/ha{\cdot}day$, TP 0.005 $kg/ha{\cdot}day$ under less than 10% agricultural land-use. In agricultural land-use of 20%-50%, these values were investigated in the range of 0.32 $kg/ha{\cdot}day$-0.73 $kg/ha{\cdot}day$ for BOD, 0.92 $kg/ha{\cdot}day$-3.32 $kg/ha{\cdot}day$ for SS, 0.70 $kg/ha{\cdot}day$-0.90 $kg/ha{\cdot}day$ TN, 0.03 $kg/ha{\cdot}day$-0.044 $kg/ha{\cdot}day$ for TP.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.75-78
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• 2014

MLCC is one of the most frequently used component in high-tech device like smart phone. Because of dynamic characteristic of piezoelectric materials which is main ingredient of MLCC, its vibration leads to acoustic noise from pcb. To solve this problem at minimal cost, company has to change only the main noise-generating MLCC to low noise-generating MLCC. To find the main noise source, this study approached to solution from a vibration point of view. From mode shapes of pcb at particular frequencies, two groups can be obtained; MLCCs soldered at where maximum deformation occurs and where anti-phase with respect to the other group appears. When the MLCC belongs to 1st group does not working, amplitude at where maximum deformation occurs decreases compared to when all MLCCs are working. This tendency also appears in noise measurement. This analysis can be put to use in various fields where require noise reduction or noise source identification.

• 천문학회지
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• 제56권1호
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• pp.23-33
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• 2023

We investigate the diffusion process of Thomson-scattered line photons in both real space and frequency space through a Monte Carlo approach. The emission source is assumed to be monochromatic and point-like embedded at the center of a free electron region in the form of a sphere and a slab. In the case of a spherical region, the line profiles emergent at a location of Thomson optical depth τ_Th from the source exhibit the full width of the half maximum σ_λ ≃ τ^1.5_Th. In the slab case, we focus on the polarization behavior where the polarization direction flips from the normal direction of the slab to the parallel as the slab optical depth τ_Th increases from τ_Th ≪ 1 to τ_Th ≫ 1. We propose that the polarization flip to the parallel direction to the slab surface in optically thick slabs is attributed to the robustness of the Stokes parameter Q along the vertical axis with respect to the observer's line of sight whereas randomization dominates the remaining region as τ_Th increases. A brief discussion on the importance of our study is presented.

• 패션비즈니스
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• 제20권6호
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• pp.32-51
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• 2016

KakaoTalk has become a reputed mobile social network and an inseparable part of people's lives by leading the mobile industry in South Korea. However, there is a lack of studies in academia regarding perception of the consumers and assessment toward the mobile marketing and services by KakaoTalk. Based on the theoretical orientation of Elaboration Likelihood Model (ELM: Petty & Cacioppo, 1986) and electronic service quality (E-S-QUAL: Parasuraman, Zeithaml, & Malhotra, 2005), this study investigates the effects of information sources (Charles & Richard, 1988), and examines the consumer perception toward the service quality of KakaoTalk. A total of 209 responses were collected, using a self-administered survey in Seoul and Gyeonggi province, South Korea from March 2015 to June 2015. A seven-point Likert scale survey was developed to measure the information sources (i.e., argument quality, post popularity, and post attractiveness), electronic service quality (i.e., efficiency, fulfillment, privacy, and system availability), attitude (i.e., usefulness, preference, and overall attitude), and behavioral intention (i.e., like intention, share intention, and purchase intention). This study reveals a consensus that an online environment is different from the traditional retail context in terms of information source and service quality. Specifically, the results indicate that argument quality greatly impacts the attitudes of the individuals and their behavioral intention toward mobile shopping via social media channel. The most powerful factor among E-S-QUAL is "efficiency." This dimension of service quality influences the customer perception of usefulness and preference as well as share and like intention toward mobile shopping on KakaoTalk.

• 한국콘텐츠학회논문지
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• 제10권4호
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• pp.91-97
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• 2010

Web 2.0 시대를 맞아 최근 웹상에는 소셜 미디어 서비스(Social Media Service)가 각광받고 있다. 환경적 변화에 맞춰 사용자의 요구를 충족시키는 소셜 미디어 서비스로써 합주서비스를 제공하고자 한다. 합주서비스는 MMMD(Multi Media Multi Device) 개념으로 음원을 제공하고자 한다. 즉, 합주곡을 하나의 재생장치를 통해 듣는 것이 아니라, 악기 별로 재생장치를 선택해 연주함으로써 오케스트라에서 음악을 감상하는 것 같은 실감을 부여할 수 있다. 목표를 충족시키기 위해서 합주곡을 구성하는 악기 별 음원을 분리하고 연주를 위해 필요한 음원을 추출하고 음원을 각 재생장치로 전달하는 작업을 AET Process로 정의하였다. 음원 간의 동기화를 제어하기 위해서 쉼표를 이용한 동기화 알고리즘을 제안하였다. AET Process와 쉼표를 이용한 동기화 처리 방법을 이용하여 사용자에게 실감 있는 합주 서비스를 제공할 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.174-174
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• 2010

Gallium Nitride(GaN) attracts great attention due to their wide band gap energy (3.4eV), high thermal stability to the solid state lighting devices like LED, Laser diode, UV photo detector, spintronic devices, solar cells, sensors etc. Recently, researchers are interested in synthesis of polycrystalline and amorphous GaN which has also attracted towards optoelectronic device applications significantly. One of the alternatives to deposit GaN at low temperature is to use Single Source Molecular Percursor (SSP) which provides preformed Ga-N bonding. Moreover, our group succeeds in hybridization of SSP synthesized GaN with Single wall carbon nanotube which could be applicable in field emitting devices, hybrid LEDs and sensors. In this work, the GaN thin films were deposited on c-axis oriented sapphire substrate by MBE (Molecular Beam Epitaxy) using novel single source precursor of dimethyl gallium azido-tert-butylamine($Me_2Ga(N_3)NH_2C(CH_3)_3$) with additional source of ammonia. The surface morphology, structural and optical properties of GaN thin films were analyzed for the deposition in the temperature range of $600^{\circ}C$ to $750^{\circ}C$. Electrical properties of deposited thin films were carried out by four point probe technique and home made Hall effect measurement. The effect of ammonia on the crystallinity, microstructure and optical properties of as-deposited thin films are discussed briefly. The crystalline quality of GaN thin film was improved with substrate temperature as indicated by XRD rocking curve measurement. Photoluminescence measurement shows broad emission around 350nm-650nm which could be related to impurities or defects.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3795-3802
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• 2022

NaI(Tl) scintillation materials are considered to be one of many materials that are used exclusively for γ-ray detection and spectroscopy. The gamma-ray spectrometer is not an easy-to-use device, and the accuracy of the numerical values must be carefully checked based on the rules of the calibration technique. Therefore, accurate information about the detection system and its effectiveness is of greater importance. The purpose of this study is to estimate, using an analytical-numerical formula (ANF), the purely geometric solid angle, geometric efficiency, and total efficiency of a cylindrical NaI(Tl) γ-ray detector with a side-through hole. This type of detector is ideal for scanning fuel rods and pipelines, as well as for performing radio-immunoassays. The study included the calculation of the complex solid angle, in combination with the use of various points like gamma sources, located axially and non-axially inside the through detector side hole, which can be applied in a hypothetical method for calibrating the facility. An extended γ-ray energy range, the detector, source dimensions, "source-to-detector" geometry inside the side-through hole, path lengths of γ-quanta photons crossing the facility, besides the photon average path length inside the detector medium itself, were studied and considered. This study is very important for an expanded future article where the radioactive point source can be replaced by a volume source located inside the side-trough hole of the detector, or by a radioactive pipeline passing through the well. The results provide a good and useful approach to a new generation of detectors that can be used for low-level radiation that needs to be measured efficiently.

• 농촌계획
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• 제21권3호
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• pp.101-112
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• 2015

The objective of this study was to investigate non-point sources (NPS) pollution and prioritize management areas affected by NPS pollution in the Saemangeum Watershed. AHP (Analytical Hierarchy Process) technique was selected to prioritize sub-watersheds for effectively managing NPS pollution in this study areas. Generation properties of NPS pollution, discharge properties of NPS pollution, and runoff properties of NPS pollution were selected and set for AHP. Weighted descriptors including indicators like numbers of livestock, land- and livestock-system loads, rainfall, and impervious area ratio were generalized from 0 to 1 and multiply each index based on screened 17 survey data. The results were visualized as maps which enable resource managers to identify sub-watersheds for effective improving water quality. The sub-watersheds located in Gongdeok-Myeon, Yongji-Myeon, Hwangsan-Myeon of Gimje-Si were selected for managing NPS pollution control areas. This result presented that these sub-watershed are more affected by the pollution from livestock-system than from land-system. The finding from this study can be used to screen sub-watersheds that need further assessment by managers and decision-makers within the study area.

• 한국멀티미디어학회논문지
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• 제16권7호
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• pp.897-904
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• 2013

The recursive circulant network G(N,d) can be widely used in the design and implementation of parallel processing architectures. It consists of N identical nodes, each node is connected through bidirectional, point-to-point communication channels to different neighbors by jumping $d^i$, where $0{\leq}i{\leq}{\lceil}{\log}_dN{\rceil}$ - 1. In this paper, we investigate the routing of a message on $G(2^m,4)$, a special kind of RCN, that is key to the performance of this network. On $G(2^m,4)$ we would like to transmit k packets from a source node to k destination nodes simultaneously along paths on this network, the $i^{th}$ packet will be transmitted along the $i^{th}$ path, where $1{\leq}k{\leq}m-1$, $0{{\leq}}i{{\leq}}m-1$. In order for all packets to arrive at a destination node quickly and securely, we present an $O(m^4)$ routing algorithm on $G(2^m,4)$ for generating a set of one-to-many node-disjoint and nearly shortest paths, where each path is either shortest or nearly shortest and the total length of these paths is nearly minimum since the path is mainly determined by employing the Hungarian method.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.716-719
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• 2005

본 논문에서 우리는 교통 네트워크가 포함된 L$_1$ 평면에서 최단거리 경로를 구하는 알고리즘을 제안한다. 교통 네트워크는 더 빠르게 움직일 수 있는 도로를 나타내는 평행한 선분들로 구성된다. 시작점 s가 주어 질 때, 알고리즘은 최단경로지도(SPM)를 만드는데, 이 지도를 통해서 s 로부터 임의의 평면상의 점 t까지의 최단거리를 O(log n) 시간에 찾을 수 있다. 우리는 이 SPM을 O(nlog n) 시간에 구하는 평면 스윕(plane sweep) 형태의 알고리즘을 설계할 것이다.