• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.859-864
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• 2008

The dynamic interaction between the moving mass and the rotating Timoshenko shaft is investigated. The moving speed of the mass is presented by a constraint equation related to the rotating speed of the shaft. The dimensionless equations of motion for the rotating shaft with a moving mass by using the Timoshenko's beam theory. The dynamic responses of this system are studied. influences of dimensionless parameters such as the rotating speed ratio. the Rayleigh coefficient and the dimensionless axial force are discussed on the transient response and the maximum deflection of the moving system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1993.04a
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• pp.115-122
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• 1993

본 연구의 목적은 다공관 소음기의 설계변수인 공동과 다공관의 치수 및 구 멍배열의 변화에 따른 휘파람소리의 발생특성을 실험에 의하여 체계적으로 구하는데 있다. 소음기의 각 설계변수마다 유속변화에 따른 휘파람소리가 발 생하는가를 확인하고 발생하게 되면 스펙트럼 분석을 통하여 휘파람 소리의 주파수특성을 구한다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.692-694
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• 2000

본 논문에서는 이진 트리 형태를 가지는 다관절체의 균형을 잡거나 이진 트리 모양으로 연결된 네트워크 상에서 단말 노드들의 부하를 균형 있게 하는데 이용할 수 있는 무게 있는 리프 이진 트리 균형 문제를 제안한다. 또한 무게 있는 리프 이진 트리 균형 문제를 리프들의 무게 변화량의 쌍의 {{{{ { l}_{ 1} }}}}-norm, {{{{ { l}_{2 } }}}}-norm, {{{{ { l}_{3 } }}}}-norm 각각을 최소로 하면서 해결하는 방법들을 제안한다. 이 방법들은 무게 있는 리프 이진 트리 균형 문제의 특성을 이용하여 n개 변수를 하나의 변수의 양의 상수배로 나타냄으로써 해결할 수 있음을 보인다.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.17-20
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• 1998

1. 서론 : 계면중합은 제조에 따른 박막의 성능 조절이 가능한 이유로 해서 역삼투용 복합막의 주요 제조 방법으로 제시되어 왔다. 계면중합을 응용하여 제조된 복합막의 성능은 반응 단량체의 종류, 용재의 종류, 단량체의 농도, 반응시간, 열처리 유무 및 온도와 시간 등에 의해 변한다. 한편 위의 변수에 절대적인 영향을 받고 아울러 단량체간의 몰 비가 성립하지 않음으로 해서 최적의 막 성능으로 제시되는 조건을 만족하기 위하여 주로 시행착오에 의한 방법을 동원하여 여러 변수에 다른 제조 막의 성능 고찰을 실시하여 왔다. (생략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6B
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• pp.390-401
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• 2007

This paper is to estimate and analyze the price elasticities of demand for mobile calls. We used the data for the period from January 2000 to December 2005 on a monthly basis. Data used are call minutes to mobile-originating(ML+MM), tariff for dispatch of fixed and mobile calls($P_L,P_M$), income(Y), and subscriber for mobile(N). In order to provide robust estimates of price elasticities, we have used two different econometric models. One is a Dynamic model which includes a lagged dependent variable and so can differentiate between long-un and short-run price elasticities using the Generalized Method of Moments(GMM). The other is a Box-Cox transformation model which is one of the most useful methods. Box-Cox transformation model shows that elasticity changes with the lapse of time. The results are as follow : Not including the price indices for land-originating, the estimate is overestimated otherwise. In Box-Cox transformation case, price elasticity had been steadily declining. And this result shows that mobile services had been changed necessities increasingly in Korea.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.93-106
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• 2011

The Korean mobile telecom market has undergone a sea change since Apple created a new mobile ecosystem with Appstore and iPhone. Many non-telecom operators have been trying hard to come up with new business strategies to gain a competitive edge. The shifting competition landscape requires a new communications policy that can further stimulate the evolving market. This is why countries around the world are upgrading their communications policies: to renew the market foundation and better respond to the ever-changing industry environment. Using the ANP(Analytic Network Process) model, this study identifies policy variables and performs quantitative analysis on their priorities. The analysis results will help prioritize policy variables under the limited amount of resources, and serve as useful guidelines for making mobile ecosystem policies.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.4
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• pp.453-460
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• 2009

For constructing 3D information using aerial photograph or video sequences, left and right stereo images having different viewing angle should be prepared in overlapping area. In video sequences, left and right stereo images would be generated by mosaicing left and right slice images extracted in consecutive video sequences. Therefore, this paper is focused on generating left and right stereo mosaic images that are able to construct 3D information and video sequences could be made for the best use. In the stereo mosaic generation, motion parameters between video sequences should be firstly determined. In this paper, to determine motion parameters, free mosaic method using geometric relationship, such as relative orientation parameters, between consecutive frame images without GPS/INS geo-data have applied. After determining the motion parameters, the mosaic image have generated by 4 step processes: image registration, image slicing, determining on stitching line, and 3D image mosaicking. As the result of experiment, generated stereo mosaic image and analyzed result of x, y-parallax have showed.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.245-256
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• 2013

This study illustrates factors that determine consumer types based on ways in which they alternate between online and offline channels for searching and eventually buying their desired products. This study conducted an online survey targeting 1,040 consumers. As per the study, consumer types fall into five groups: 1) on-on type(online search${\rightarrow}$online buying), 2) off-off type(offline search${\rightarrow}$offline buying), 3) on-off type(online search${\rightarrow}$offline buying), 4) off-on type(offline search${\rightarrow}$online buying), and, 5) on-off-on type(online search${\rightarrow}$ offline search${\rightarrow}$nline buying). The primary factors that determine how the different consumer types switch between online and offline channels are price orientation, convenience orientation,, risk-aversion orientation, and channel familiarity. Although they feel cross-channel shopping can be cumbersome, the findings show that cross-channel consumers would gladly switch channels to buy cheaper and proven products. The findings of this study will be useful for businesses that have both online and offline channels and point out the theoretical aspects of the decision-making process as consumers switch between channels.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.873-877
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• 2012

지형인자는 하천유역의 홍수량을 산정하는데 있어 매우 중요한 인자이다. 유역의 지형인자를 통해 홍수유출 모형에 적용하기 위한 매개변수를 산정하고 강우-유출모형에 적용시켜 홍수수문곡선을 추정하고 있다. 그러나 우리나라에 적합한 매개변수의 추정방법은 아직 미흡하여 외국에서 개발된 경험식을 주로 이용하고 있다. 본 연구에서는 하천유역의 홍수유출을 계산할 때 입력인자로 사용되는 집중시간 및 저류상수 등과 같은 매개변수를 산정하는데 있어 사용되는 경험식들의 조합에 따른 홍수유출량의 변화양상을 분석하였다. 시험유역으로 청미천 유역을 선정하여 각 경험식에 따른 매개변수를 산정하여 비교하였다. 강우-유출 모델로 HEC-HMS를 적용하였으며 모의시 관측된 강우 자료를 전 유역에 걸쳐 분포시키기 위하여 IDW(Inverse Distance Weighted) 방법을 사용하고 공간적으로 분포된 강우자료와 지형자료를 이용한 유출모의가 가능하도록 ModClark(Modified Clark) 방법을 사용하였다. 또한, 중규모 이상의 큰 유역의 경우는 유입시간이 유하시간에 비해 상대적으로 짧아 유입시간을 무시하고 유하시간을 집중시간으로 취급하므로 각 소유역에 대한 집중시간 산정은 유하시간을 산정하는 방법을 적용하였다. 본 연구에서는 집중시간 및 유하시간 산정에 Kirpich, Rziha, Kraven(I), Kraven(II) 공식을 적용하였고, 저류상수 산정에 Clark, Linsley, Sabol, Russel, Peters 공식을 적용하였다.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.190-198
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• 2008

In this stduy, the column experiments were carried out assuming the soil was contaminated by leakage of gasoline containing MTBE from USTs and pipes around gas stations. Then, characteristics of MTBE transport in the soil were investigated using CXTFIT program. The column experiments with different soil properties, moisture content, organic matter content and flow rate were carried out. Some parameters(D, R, $\beta$, $\omega$) used in two-site non-equilibrium adsorption model were obtained from measuring the MTBE concentration in injection-liquid and in effluent and using CXTFIT program. In addition, The characteristics of MTBE transport in the soil was found using BTCs and obtained parameters. Consequently, the advection decreased as the increase of the content of fine particle and organic, while the MTBE transport by advection was enhanced as increasing flow rate and moisture content.