• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.34-46
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• 2020

Computational assessment of gas-dynamic characteristics is explored for a three-dimensional counter-flow thrust vector control system in a rectangular supersonic nozzle. This convergent-divergent nozzle is designed by Method of Characteristics and its design Mach number is specially set as 2.5. Performance variations of the counter-flow vector system are illustrated by varying the gap height of the secondary flow duct. Key parameters are quantitatively analyzed, such as static pressure distribution along the centerline of the upper suction collar, deflection angle, secondary mass flow ratio, and resultant thrust coefficient. Additionally, the streamline on the symmetry plane, three-dimensional iso-Mach number surface contour, and three-dimensional turbulent kinetic energy contour are presented to reveal overall flow-field characteristics in detail.

• Informatization Policy
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• v.20 no.2
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• pp.73-90
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• 2013

Rational debate and public conversation in the public sphere of social network are crucial conditions for realizing deliberative democracy. However, negative communication can occur online more frequently than in the real space, and mutually hostile messages are appearing. In the electoral process, citizens combining for particular candidates have made personal attacks against, abused and slandered the opposing candidates. Then, how and to what degree has the flaming behavior been appearing in the elections? Are there influencers to propagate the flaming behavior? And how flaming are these influencers, compared to internet users? This research focuses on the flaming behavior which occurred during the reelection for Seoul Mayor, in order to diagnose the role of social network as an online public sphere. This study analyzes the spreading degree of flaming messages depending on each issue, and the differences of messages between influencers and normal users. There was frequent flaming behaviors to distribute biased information which criticized, laughed at and maliciously attacked individual candidates. Moreover, influencers who advanced leading opinions, displayed a higher flaming degree than normal users.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.279-279
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• 2019

본 연구는 안동 하천실증연구센터에서 수행된 RIED 실험의 일환으로 실험수로내 식재된 버드나무 식생패치의 밀도에 따른 표면흐름의 특성을 검토하는 실험이다. 실험의 목적은 식생의 침수수위에 따른 식생주변 및 하도의 흐름특성을 검토하는 것으로 침수 수위조건은 유량공급조건의 변화를 통해 재현하였다. 본 연구에 사용된 LSPIV 기법은 하도내 입자투여를 통해 영상을 이용하여 입자간 이동속도를 분석하여 흐름장을 분석하는 것으로 본 연구에서 사용된 입자는 강랭이를 사용하였으며, 영상촬영은 크레인을 이용하여 캠코더를 이용하여 수로 상부에서 흐름영상을 취득하였다. 실험수로는 저면폭 3m, 만제폭 11m 사면경사 1:2의 구조로 이루어진 사다리꼴 형태의 직선수로로 이루어져 있다. 식생패치는 동일수로내 상부기준 32m 간격으로 설치되어 있으며 패치의 크기는 $4{\times}1.5m$의 크기로 이루어져 있다. 그림 1은 상공에서 촬영된 영상을 나타낸 그림으로 실험수로 및 LSPIV 분석을 위해 투하된 입자를 나타내는 그림이다. PIV 분석프로그램을 이용하여 분석된 식생대 및 하도영역에서의 유속장은 그림 2와 같다. 영상분석은 30초영상(900 frame)을 이용하여 분석하였다. 실험결과 식생패치 설치지점에서는 주흐름이 발생하는 우안측에서 높은 유속이 발생하고 약간의 편향된 흐름이 나타나는 것으로 확인되었다. 식생후면에서는 식생으로 인한 흐름의 차단 및 스크린효과로 인해 유속의 저감되는 것을 확인할 수 있다. 밀도에 따른 패치 후면부에서는 높은 밀도를 갖는 첫 번째 패치에서 유속의 저감효과가 높게 나타났으나 유량조건에 차이가 발생하는 것으로 나타났는데 이는 수위상승으로 인한 식생의 침수면적과 관계가 있는 것으로 판단된다.

• Journal of the Korea Society of Computer and Information
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• v.7 no.1
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• pp.161-173
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• 2002

The increasing disposable time through advancing information has come to make the tourism industry as well as the information communication industry glow in the 21st century We cannot make rational decision without proper guide information. It is impossible to anticipate tourism Products which are invisible products consisting of a variety of basic combinations of products. Tourists are getting dissatisfied with tourism experts' distorted guidance every year. A recent survey shows that the current tourism information system can't meet the need of tourists who are informative and individualized. This paper presents tourism information system that offers the most appropriate tour courses depending on the tastes of tourists by utilizing expert system, artificial intelligent applied technology. This paper is the first attempt to maximize comsumer satisfaction by developing the intelligent agent system that is able to reflect the traits of individualized customers' in the tourism industry The establishment of this system will contribute to activating the tourism industry, ultimately, by decreasing inconveniencies and tour schedules appropriate to the purpose of individual tours.

• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.221-228
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• 2017

We measured the refractive index of a mixed polymer (NOA61, NOA84) in the liquid and solid states. First we made a hollow prism and filled it with UV (ultraviolet) epoxy. Measurement of the apex angle and the minimum-deviation angle gave the refractive index of the liquid polymer. To measure the refractive index of the solid polymer, an additional structure was included in the hollow prism, and the UV epoxy filling in the hollow prism was hardened. In both cases of liquid and solid polymers, the refractive index of the mixed polymer turned out to be proportional to the mix ratio. These results provide a method to vary the focal length of a double stacked cylindrical microlens array using UV epoxy.

• Journal of Digital Convergence
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• v.16 no.11
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• pp.477-485
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• 2018

Beyond the mid-2010s, there has been increasing cases of using 'Reminiscence' as a trigger for recalling 'Past' in pre-production process of creative contents. In previous researches on this phenomenon, it has been recognized that retro, recall, compassion, and memory are similar. In order to look closely to grasp the psychological tendency of the contents user in detail, the study about 'Reminiscence' was conducted. The researcher analyzed 'Reminiscence' as a process of restructuration based on the experience and desire of the person individual which were derived from the past and further analyzed it as a lack of desire due to the time can never return. The study hopefully can make a balance against the cutting edge content distribution technology biased production tendency.

• Journal of Wetlands Research
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• v.23 no.2
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• pp.173-182
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• 2021

It is important to extract and assess low-flow recession characteristics for water resources management in the upper reaches of a stream. It is difficult to express the groundwater flow recession characteristics for streamflow synthetically. The linear recession model has been widely used by baseflow recession analysis for reason of simplicity and convenience, but recent studies show that nonlinear recession models fit well, and the relationship between the reservoir storage of shallow unconfined aquifers and the groundwater discharge was to be identified as nonlinear in the literature based on the analysis of numerous streamflow recession curves. The objective of the study is to decode these nonlinear characteristics, including evaporation loss, storage, and recharge of groundwater using streamflow. By analyzing the observed time series of streamflow from the study area, which is the Pyeongchang River basin in Korea, the main components of the underlying groundwater balance, namely, discharge, evaporation loss, storage, and recharge, can be identified and quantified. As a result of the study, depletion of groundwater by evapotranspiration losses through the water uptake of tree roots was found to bias the recession curves and the estimated reservoir parameters. The seasonality of both rainfall and potential evaporation, analysis of the recession curves, stratified according to time of the year, allowed the quantification of evapotranspiration loss as a function of a calendar month and stored groundwater storage.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.2
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• pp.48-58
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• 2022

This study tried to assess the applicability of a hand-held LiDAR for measuring the geometric structures of forest trees including diameters at a breast height(DBH) and tree height(H). A traditional method using tapelines was conducted to analyze the accuracy of the LiDAR instrument in the Taebaeksan national park in South Korea. Four statistical indices which are bias, root mean square error, mean absolute error, and correlation coefficient were employed to compare the measurements by the LiDAR instrument and traditional method. The DBHs from the LiDAR were very similar to those from the traditional method. And it indicated that the LiDAR is sufficient to be a alternative of a traditional method. However, there was a limitation in assessing the accuracy of LiDAR for measuring tree height by comparing the measurements by observer's eyes since they included different error sources. Further study is needed to assess the accuracy of LiDAR instrument for tree height through more reliable measurements.

• Journal of Korea Entertainment Industry Association
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• v.14 no.8
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• pp.63-75
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• 2020

This paper researches the relationship between Youtube K-pop music video views and visual characteristics. K-pop music video, which is the subject of study has intrigued the world since 'Gangnam Style' became Youtube's most viewed video in 2012. This paper questions the existence of element that are related to music video views which is not externally visible and the availability of the discovering the specific element. Previous studies had difficulty in searching the inherent elements of the music video associated with views because they chose a research method that compares music videos based on one or two pieces of work and had a biased result. Therefore, this paper goals to divide nine music videos according to the number of views in three groups and analyze their visual characteristics to find out the differences between the groups and their each features. This paper will contribute to the development of music video field in Youtube market where the number of views is getting more important recently.

• Journal of Korean Philosophical Society
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• no.89
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• pp.37-67
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• 2010

The 21 Century is definded as an age of culture or image characterized by the fact, that modern society are being overwhelmed with virtual reality, that is full of visual images. The cultural concentration on the visual image and the excessive tendency to attend it become not only today but also ever as the leading style of culture. Nevertheless, it is particularly noteworthy that the visual image has become so one of the basic conditions of modern society, that one holds it as the society of the spectacle. So can the problem of seeing that resulted from the oculocentric culture, that is the problem of the fundamental relationship between the world and the eyes of human beings, be examined in the phenomenological sense. For this study, I believe that 『Phenomenologie de la Perception』 of Merleau-Ponty provides a important approach. The theme of this study is to refer, first, how man has dealt with the seeing in the history of philosophy, such as Plato, Kant, and Merleau-Ponty, who although not the anti-oculocentricism, but also makes serious reflection about an excess of visual images. Second, it is to explain what characteristics and problems are located in these considerations, and thirdly, it must be brought into the light, what is the essence of the seeing with regard to the beauty, the truth and the morality.