• Environmental and Resource Economics Review
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• v.33 no.1
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• pp.59-86
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• 2024

Recently, research on city gas demand is increasing by reflecting the characteristics of each region. The similarity of the social structure of the adjacent region and the density of the supply infrastructure induce spatial correlation with the clustering that has a microscopic relationship between regions. Accordingly, as a result of analyzing the spatial correlation after dividing the demand for city gas for civilian use into a total of 54 regions based on the jurisdiction of 34 city gas companies, it was confirmed that there was a positive spatial correlation from a global and local perspective. In this study, the demand for city gas for civilian use for 54 regions from January 2014 to December 2022 was composed of panel data, and the spatial panel regression analysis and the general panel regression analysis were compared, and it was found that the spatial error model (SEM) was the most suitable model. This presents policy and practical implications by confirming that the demand for city gas for civilian use in one region has a significant relationship with the adjacent region.

• Journal of Technology Innovation
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• v.17 no.1
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• pp.1-48
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• 2009

Recently we have found some symptoms that R&D fiscal incentives might not work well what it has intended through the analysis of current statistics of firm's R&D data. Firstly, we found that the growth rate of R&D investment in private sector during the recent decade has been slowdown. The average of growth rate (real value) of R&D investment is 7.1% from 1998 to 2005, while it was 13.9% from 1980 to 1997. Secondly, the relative share of R&D investment of SME has been decreased to 21%('05) from 29%('01), even though the tax credit for SME has been more beneficial than large size firm, Thirdly, The R&D expenditure of large size firms (besides 3 leading firms) has not been increased since late of 1990s. We need to find some evidence whether fiscal incentives are effective in increasing firm's R&D investment. To analyse econometric model we use firm level unbalanced panel data for 4 years (from 2002 to 2005) derived from MOST database compiled from the annual survey, "Report on the Survey of Research and Development in Science and Technology". Also we use fixed effect model (Hausman test results accept fixed effect model with 1% of significant level) and estimate the model for all firms, large firms and SME respectively. We have following results from the analysis of econometric model. For large firm: i ) R&D investment responds elastically (1.20) to sales volume. ii) government R&D subsidy induces R&D investment (0.03) not so effectively. iii) Tax price elasticity is almost unity (-0.99). iv) For large firm tax incentive is more effective than R&D subsidy For SME: i ) Sales volume increase R&D investment of SME (0.043) not so effectively. ii ) government R&D subsidy is crowding out R&D investment of SME not seriously (-0.0079) iii) Tax price elasticity is very inelastic (-0.054) To compare with other studies, Koga(2003) has a similar result of tax price elasticity for Japanese firm (-1.0036), Hall((l992) has a unit tax price elasticity, Bloom et al. (2002) has $-0.354{\sim}-0.124$ in the short run. From the results of our analysis we recommend that government R&D subsidy has to focus on such an areas like basic research and public sector (defense, energy, health etc.) not overlapped private R&D sector. For SME government has to focus on establishing R&D infrastructure. To promote tax incentive policy, we need to strengthen the tax incentive scheme for large size firm's R&D investment. We recommend tax credit for large size film be extended to total volume of R&D investment.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.99-104
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• 2013

Replacement of sensor nodes for monitoring a wide range area such as mountains and forests needs a lot of time and cost. Using new and renewable energy around them can maximize the lifetime of wireless sensor networks, in which solar energy is infinite energy source that is available in 365 days. To design these sensor networks, solar energy model is essential and to estimate and analyze the overall photovoltaic energy. Using this, we can figure out important data such as the size and performance of solar panel needed. However, existing researches for solar energy harvesting consider parts of many factors to influence the quantity of solar energy gathered. In this paper, we suggest advanced solar energy harvesting model considering angular loss (solar cell panel), overheat loss (solar cell), rechargeable battery heat and cooling for each monthly properties. From our experimental results according to outdoor temperature, panel angle and the surface temperature of solar panel, we show these impact factors are correctly configured.

• Journal of the Economic Geographical Society of Korea
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• v.15 no.4
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• pp.601-614
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• 2012

This paper is aimed to analyze the determinants and their relative importance that affect regional competitiveness in the era of globalization and climate change. The panel model was set by a balanced panel data for 7 metropolitan areas & 9 provinces and for the period of 2001~2010. Gross regional income per capita is used as the dependent variable and competitiveness-based factors, economic production factors, and climate change adaptation factors are selected as the explanatory variables. In this study, Model 1(typical regional competitiveness model) and Model 2 (added adaptation to climate change adaptation factors) were compared. The important findings can be summarized as follows. The most influential determinants on regional competitiveness are the ratio of knowledge-based industries and human capital and energy inefficiencies decrease the regional competitiveness. Compared to Model 1, Model 2 showed that the effects of the regional openness and the technology innovation capital are relatively more influential in Model 2. The results of this empirical study provide policy implications to strengthen the regional competitiveness in the future of the era of globalization and climate change.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.123-125
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• 2018

태양광발전시스템은 낮은 효율의 PV 패널을 사용하여 최대의 전력을 생산하기 위해 PV 패널의 최대전력점에서 운전하는 MPPT(Maximum Power Point Tracking) 제어가 반드시 필요하다. 기존의 MPPT 알고리즘은 대부분 경사법에 기초하고 있으며 그 중 대표적인 방법이 P&O(Perturb and Observe) 알고리즘이다. P&O 알고리즘의 MPPT 성능을 좌우하는 두 가지 인수는 MPPT 제어주기와 변량전압의 크기이다. MPPT 제어기의 빠른 동특성과 극대화된 효율을 위한 최적의 MPPT 제어주기와 변량전압의 크기를 결정하기 위해서는 실제 날씨 환경에서 다양한 일사량 프로파일 패턴에 대한 MPPT 제어기의 성능분석이 필수적이다. 본 논문에서는 대한민국 중부지역의 전형적인 맑은 날씨와 흐린 날씨에서 실제 일사량을 측정하고, 취득한 일사량데이터를 기초로 저자가 개발한 다이오드 등가모델을 적용하여 시뮬레이션을 수행하였다. 이를 기반으로 MPPT 제어주기의 설정값에 따른 PV 패널의 전력생산량을 예측하여 MPPT 목표 효율을 극대화할 수 있는 최적의 MPPT 제어주기를 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.49-51
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• 2003

가입자망과 메트로 광 가입자망에서 광범위한 적용범위에 대해 광 기술을 선도하는 기존의 WDM은 증가하는 사용자 수를 수용하는 데 어려움을 가지며 WDM은 채널간의 잡음에 의한 제한과 유효 채널의 최대가 WDM 채널에서 광 증폭기 이득의 균일성에 의해 제한받는다. 따라서 사용자 수를 증가시키고 데이터량을 확장시킬 수 있는 CDMA 기술 도입이 하나의 대안으로 요구된다. 본 논문에서는 SMF에서 수십 km 거리를 갖는 가입자망에서 Prime sequence code를 사용한 2.5Gb/s 광 COMA 신호의 색분산 패널티에 대해 연구하였다. 시스템 모델에서, 색분산 패널티, 파형과 디코드된 신호의 아이 다이어그램(eye diagram)이 결과로써 보여지며, prime sequence code 수의 증가에 대해 Chirp 파라미터를 갖는 코드화된 신호의 색분산 패널티를 보인다. 이러한 접근은 pseudo-orthogonality를 가지는 비동기식 광 CDMA의 디자인에 특히 적합할 것이다.

• Journal of Korea Society of Industrial Information Systems
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• v.29 no.2
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• pp.191-204
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• 2024

This study analyzes the effects of manufacturing firms' R&D investment on sales according to global political economic uncertainty. The variables in this research include the firm's R&D investment, sales, which serves as an indicator of the firm's performance, and the Global Economic Policy Uncertainty (GEPU) index, which reflects situations of global political economic uncertainty. Panel data analysis is conducted by using a total of 96 quarters of data spanning 24 years from 2000 to 2023 based on manufacturing firms in the Wharton Research Data Services' Compustat Database. We study the impact of firm's R&D investment on sales by considering the Global Economic Policy Uncertainty index, which was relatively underestimated in previous research, as moderating variable, and present a new direction for research by analyzing the time lag effect. We suggest effective R&D investment strategy for firms.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.238-241
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• 2018

본 연구는 한국복지패널 제11차 데이터를 활용하여 노인의 삶의 만족도와 이전소득(공적이전, 사적이전 소득)의 관계를 규명하고자 시도되었다. 분석결과, 일반가구 노인의 경우 공적이전 소득이 삶의 만족도에 유의미한 정(+)적인 영향을 미치는 반면, 저소득가구 노인의 경우 사적이전 소득이 삶의 만족도에 유의미한 정(+)적인 영향을 미치는 것으로 분석되었다. 이러한 결과는 일반가구 노인의 경우 공적이전 소득이 1,019.2만원(월평균 84.9만원)으로 공적이전 소득이 소득안정화 효과로 나타나 삶의 만족도를 높이는 것으로 예측할 수 있다. 그러나 저소득가구 노인의 경우 일반가구 노인의 공적이전 소득의 절반 수준인 508.5만원(월평균 42.4만원)으로 나타났다. 이는 저소득가구 노인의 경우 비록 "마음이 편하지 않는" 소득원천인 사적이전 소득이 불안정한 소득안정화 부족분을 채워주어 삶의 만족도를 높이는 것으로 추정할 수 있다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.216-218
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• 2019

태양광발전시스템은 최대의 전력을 생산하기 위하여 PV 패널의 운전을 최대전력점에서 동작하게 하는 MPPT(Maximum Power Point Tracking) 제어가 필요하다. 그중 대표적인 방법인 P&O(Perturb and Observe) 알고리즘은 전류와 전압을 측정하여 계산된 전력의 값이 최대가 되는 전압의 운전점을 찾는다. 그러나 센서의 측정오차로 인하여 발전전력의 계산 및 전압의 제어에 불규칙한 오차가 발생하여 정확한 MPP 운전점을 찾지 못하는 문제가 발생한다. 본 논문에서는 전형적인 맑은 날씨와 흐린 날씨에서 취득한 일사량 데이터와 전류 및 전압 센서의 오차를 고려하여 P&O 알고리즘에 의한 전력 생산량을 시뮬레이션 한다. 시뮬레이션 분석을 통해 실제 날씨 및 센서허용오차 조건에서 MPPT 목표 효율을 극대화할 수 있는 최적의 MPPT 제어주기와 변량전압의 크기를 제시한다.

• Journal of the Korean Data and Information Science Society
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• v.26 no.3
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• pp.631-638
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• 2015

In this paper, we configured the panel data of four years using the information of Higher Education In Korea (2010~2013) and studied the influence of tuition and scholarships on the stop-out rate of national university and private university separately through a panel analysis. Three models are implemented considering various variables suck as faculty-student ratios, employment rate, per pupil expenditure, average tuition, and per pupil scholarship. This study showed that the lower net tuition and the higher per pupil off-campus scholarship lowered the stop-out rate at national universities and the lower tuition and the higher per pupil scholarship lowered the stop-out rate at private universities.