• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.2
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• pp.9-16
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• 2015

The control law for simultaneous pressure and thrust control of solid DACS(Divert Attitude Control System) is suggested. To regulate the two variables effectively, the control structure of sequential loop closer is applied to the system considering the physical characteristics of each variable and the weighted pseudo-inverse method is suggested to allocate effective command for indeterminate system. Also, the pressure guidance law for safe and high acceleration is applied to the homing stage to verify the effectiveness of the command distribution.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.53-61
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• 1989

A morphological analysis is described to extract the informations which are required in syntactic and semantic analysis of the Korean language. The noun and particle are separated in a noun phrase, the selecting conditions are specified to analyze the compound noun and a restoring rule is represented to process the irregular compound noun. The stem and ending are separated in normal verbals and a logical representive form is proposed to the anomalously inflected word and contracted vowels. The logical representation is composed of the attribute value an analyzing rule. The redundancy of noun is reduced in the dictionary as the verb of a "Nounformed HA-" is processed by "noun" and "HA-", separately and a predicative "IDA" is analyzed by Q parameter. The processing form of negation is also derived and the morpheme and basic structure of compound predicative parts are presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.340-340
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• 2015

기상이변에 따른 강우강도의 증가는 국지성 집중호우로 나타나게 되고, 이러한 강우양상은 하천에서의 홍수위 증가로 나타나 여러 가지 하천재해가 발생하게 된다. 본 연구에서는 대하천으로 유입되는 지류 합류부에서의 수리학적 특성을 살펴보기 위한 사전 연구로 비교적 규모가 큰 지류하천에 대한 부정류 모의를 수행할 수 있는 홍수추적모형을 구축하였다. 대상 하천은 지류 내 하도가 루프의 형태를 띠고 있는 밀양강을 대상으로 선정하였다. 낙동강의 제1지류인 밀양강에서 낙동강 합류부로부터 30.74 km 상류에 위치한 밀양강의 상동수위관측소를 상류단으로 선정하고 낙동강과 합류하는 밀양강 하류단을 대상구간으로 선정하였다. 상류 경계단인 상동수위관측소에서 측정된 수위자료는 유량자료로 환산하여 상류단 경계조건으로 사용하였으며, 하류단 경계조건은 낙동강 본류의 수산교 수위관측소와 삼랑진 수위관측소에서 측정된 수위자료를 밀양강 합류부까지의 거리 보정을 통해 밀양강 하류단의 수위자료로 사용하였다. 그림 1은 밀양강의 상동수위관측소에서부터 낙동강 합류부까지 구간에 대한 모식도를 나타내고 있으며, 그림 2는 밀양1 지점에 대한 모의결과를 나타내고 있다. 단장천 유입 이후 밀양강 본류가 두 개의 루프형으로 분류되었다가 다시 합류하는 하도의 형태를 가지고 있어 보다 복잡한 검증과정이 요구되었다. 본 연구에서 구축된 밀양강에 대한 수리학적 해석모형은 지류 합류부에서의 배수영향에 의한 수리특성을 분석하는데 활용될 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.436-436
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• 2018

하천의 조도계수는 하상 입자들의 크기 및 형상, 식생, 수로의 만곡 등 흐름특성에 영향을 주는 복합적인 경험적 매개변수이므로 그 값을 정확히 산정하는 것은 매우 어렵다(Chow, 1959). 제주도 산지하천은 하상이 매우 불규칙하고 조도계수의 불확실성으로 인해 정확한 홍수위, 홍수량 산정이 어렵다. 또한 하상경사가 매우 급하여 상류와 사류가 복합적으로 발생하므로 수치모의 시 수위차가 크게 발생할 우려가 있다. 따라서 현장실측 기반의 하천 조도계수 산정을 통한 홍수위, 홍수량 산정에 정확도를 향상시킬 필요가 있다. 이 연구에서는 제주도 북부지역의 건천(한천, 병문천, 독사천, 산지천)을 대상으로 하상재료를 직접 실측하여 하상 입경을 이용한 조도계수를 산정하였다. 실측 방법은 대상하천의 현장답사 및 현장조사를 사전에 실시하였으며, 하천의 종단 방향으로 1km 간격, 100개 이상의 하상재료를 표본으로 취하고 선격자법을 적용하였다. 대상하천 하류부의 좌안, 우안은 대부분 하천 정비에 의한 제방 구축이 되었으며, 상류부는 경사가 급한 암질로 구성되어 있으므로 하상을 중심으로 구성물질의 입경과 조고를 측정하여 상류 흐름의 영향범위를 고려한 조도계수를 산정하였다. 표본 측정시 점 사주, 여울, 웅덩이 등 국부적으로 하상재료의 변화가 심한 구역은 피하고 가급적 해당 구역에서 보편적으로 산재된 하상재료를 선택하였다. 향후 부정류 모형인 HEC-RAS를 이용하여 실측 유량과 수위를 적용한 조도계수를 산정한다면 보다 정밀한 조도계수를 산정할 것으로 판단된다.

• Annual Conference on Human and Language Technology
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• 2021.10a
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• pp.281-286
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• 2021

뉴스 헤드라인에 제3자의 발언을 직접 인용해 전언하는 이른바 '따옴표 저널리즘'이 언론 보도의 객관주의 원칙을 해치는지는 언론학 및 뉴스 구독자에게 중요한 문제이다. 이 연구는 온라인 포털사이트를 통해 실시간 유통되는 한국어 기사의 정확성을 판별하기 위한 기계학습(Machine Learning) 모델을 제안한다. 이 연구에서 제안하는 모델은 Edit Distance와 FastText 기법을 활용해 기사 제목과 본문 내 인용구의 유사성을 측정하고, XGBoost 모델을 활용해 최종 분류한다. 아울러 이 모델을 통해 229만 건의 뉴스 헤드라인에 대해 직접 인용구가 포함된 기사가 취재원의 발언을 주관적인 윤색없이 독자들에게 전하고 있는지를 판별했다. 이뿐만 아니라 딥러닝 기반의 KoELECTRA 모델을 활용해 기사의 제목 내 인용구에 대한 감성 분석을 진행했다. 분석 결과, 윤색이 가미되지 않은 직접 인용형 기사의 비율이 지난 20년 동안 10% 이상 증가했으며, 기사 제목의 인용구에 나타나는 감정은 부정 감성이 긍정 감성의 2.8배 정도로 우세했다. 이러한 시도는 앞으로 계산사회과학 방법론과 빅데이터에 기반한 언론 보도의 평가 및 개선에 도움을 주리라 기대한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.1-7
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• 2011

In this paper, based on an isogeometric approach, we have developed a shape design optimization method for plane elasticity problems subjected to design-dependent loads. The conventional shape optimization using the finite element method has some difficulties in the parameterization of geometry. In an isogeometric analysis, however, the geometric properties are already embedded in the B-spline basis functions and control points so that it has potential capability to overcome the aforementioned difficulties. The solution space for the response analysis can be represented in terms of the same NURBS basis functions to represent the geometry, which yields a precise analysis model that exactly represents the normal and curvature depending on the applied loads. A continuum-based isogeometric adjoint sensitivity is extensively derived for the plane elasticity problems under the design-dependent loads. Through some numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.6
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• pp.145-155
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• 2021

This study aims to examine the results of start-up policies of the previous government (2013-2017) and the current government (2017-2022). We would like to compare the perceptions of founders on the domestic start-up environment in 2016 and 2021. Based on the data (GETR) that surveyed the perception of the startup environment in 2016, a trend survey was conducted to compare the perception of the start-up environment of founders in 2021. As a result of the study, the founder's perception of the domestic start-up environment changed positively overall, but there was no significant change in the perception of 'tax adequacy', 'easy to recover investment', and 'easy to transfer technology'. In addition, the perception of the start-up environment of livelihood founders was negative compared to opportunity-type start-ups. As such, different results were found for each type of start-up. This study analyzed the difference in perception of the past and present start-up environment from the perspective of founders. In particular, I would like to propose a plan to improve the quality of the domestic start-up environment by seeking support measures for livelihood-type start-ups that have collapsed due to COVID-19.

• Korean Journal of Social Welfare Studies
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• v.40 no.2
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• pp.145-182
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• 2009

This study aimed to build up the concept of culture welfare. For this purpose, we analyzed the practitioners' understanding about culture welfare in culture and social welfare by Modified Grounded Theory Approach. The results showed that the practitioners did not understand the concept of culture welfare clearly, and revealed being in confusion. Their understandings about culture welfare were classified into five types, 1) a type denying a terminology, culture welfare itself, 2) a type without awareness about culture welfare, 3) a type regarding culture welfare as sub realm in the special domain of culture and social welfare, 4) a type undividing and integrating culture and social welfare, 5) a type recognizing an independent domain of culture welfare. But despite of large deviation like this, the practitioners were common to give emphasis on giving opportunities to everyone in the enjoyment of culture, for heightening the quality of life. Summing up, culture welfare is defined as 'all direct and indirect effort in culture and arts, in a narrow sense to economical vulnerable class, and in a broad sense to everyone, to raise cultural susceptibility, creative thinking, and potential competence for realization a life worthy of man. The significance of this study is in establishment the definite and practical concept of culture welfare through a deep analysis the practitioners' understanding. This will give the theoretical basis to the study and the development of various programs in culture welfare.

• Journal of Internet Computing and Services
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• v.25 no.4
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• pp.109-119
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• 2024

This study aims to contribute to the initial research on on-device AI in an environment where generative AI-based services on mobile and other on-device platforms are increasing. To derive success strategies for generative AI-based chatbot services in a mobile environment, over 200,000 actual user experience review data collected from the Google Play Store were analyzed using the LDA topic modeling technique. Interpreting the derived topics based on the Information System Success Model (ISSM), the topics such as tutoring, limitation of response, and hallucination and outdated informaiton were linked to information quality; multimodal service, quality of response, and issues of device interoperability were linked to system quality; inter-device compatibility, utility of the service, quality of premium services, and challenges in account were linked to service quality; and finally, creative collaboration was linked to net benefits. Humanization of generative AI emerged as a new experience factor not explained by the existing model. By explaining specific positive and negative experience dimensions from the user's perspective based on theory, this study suggests directions for future related research and provides strategic insights for companies to improve and supplement their services for successful business operations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.9
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• pp.44-50
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• 2002

Recently, a envelope tracking(ET) amplifier that improves efficiency by changing of the bias according to the RF input level is presented to use for a high power amplifier of cellular radio handset using CDMA. The input and the output impedances of the ET amplifier may be varied by changing of the bias of the amplifier, and it makes the amplifier having low gain, low efficiency, and high input and output VSWR. In order to improve the input and the output mismatch of the amplifier, in this paper, two types of ET amplifier are suggested. In case of an ET amplifier using varactor diode, in experimentation, gain is improved about 7dB and the power consumption of the amplifier is better about 60% than that of the conventional amplifier. In case of a base voltage controlled ET amplifier, the gain and power consumption of the amplifier is improved about 9dB and 40% than those of the conventional amplifier, respectively.