H<SUB>∞</SUB> Control Based on LPV for Load Torque Compensation of PMSM

Hoonyoung Lee,Youngwoo Lee,Donghoon Shin,Chung Choo Chung 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper proposes H∞ control based on linear parameter varying(LPV) systems for load torque compensation of the permanent magnet synchronous motors(PMSMs). The proposed method consists of torque modulation, commutation scheme and LPV H∞ controller. The dynamics of PMSMs was represented as the LPV systems depend on varying parameters. By the LPV modeling, we designed H∞ controller. Stability is proven by Lyapunov theorem. Finally, simulations are performed to show that the proposed method has a good performance of load torque compensation.

Slowdown of spring green-up advancements in boreal forests

Park, Hoonyoung,Jeong, Su-Jong,Ho, Chang-Hoi,Park, Chang-Eui,Kim, Jinwon Elsevier 2018 Remote sensing of environment Vol.217 No.-

<P><B>Abstract</B></P> <P>There is a consensus that the spring phenology of deciduous forests is advancing in response to global warming. Since the late 1990s, however, this tendency of spring phenology advancement has been weakened in over 60% of boreal forests, particularly in Siberia (−0.58 day yr<SUP>−1</SUP> for 1982–1997 vs. −0.17 day yr<SUP>−1</SUP> for 1982–2013) and northwestern North America (NWNA; −0.42 day yr<SUP>−1</SUP> for 1982–1997 vs. 0.07 day yr<SUP>−1</SUP> for 1982–2013). This study investigated the major factor in the weakening trends in the advancement of the start of the growing season (SOS) based on the satellite-observed normalized difference vegetation index (NDVI) in two regions by quantifying the effects of four climatic fields—winter duration (WD; the number of freezing days), pre-season temperature (PT; accumulated temperature from late winter to early spring), green-up temperature (GT; accumulated temperature around the green-up date), and pre-season precipitation (PR; accumulated precipitation before the green-up date)—on changes in the spring green-up trend. The GT explained the majority of the slowdown in the SOS trends in recent decades. In Siberia, the GT increases contributed to the advancement of the SOS during the 1980s and 1990s; however, the GT increase reduced to less than half of these periods resulting in a slowdown of the SOS advancing trend since the early 2000s. In NWNA, GT increases and WD shortening drove the SOS advancement until the late 1990s; however, both effects have been diminished to near zero to result in no further SOS advancements. This study demonstrates that the recent slowdown of the SOS advancing trends over Siberia and NWNA was largely attributed to the weakening of the warming trends, rather than the sensitivity changes of spring phenology to climate variables. This study suggests that the natural climate variability strongly affects the decadal variations in the boreal forest spring phenology.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Satellite data reveals a shift in large-scale spring phenology trends. </LI> <LI> The advancing of spring phenology weakened in boreal forests after the late 1990s. </LI> <LI> We assessed the influence of climate variables on the slowdown of phenology trends. </LI> <LI> This slowdown is attributed to weakened warming rather than changes in sensitivity. </LI> </UL> </P>

Combining Judgments for Better Decisions : A Study for Investigating Effective Combining Schemes

Lee, HoonYoung 한국경영과학회 1996 韓國經營科學會誌 Vol.21 No.3

Facing decision-making tasks, managers frequently make judgments. However, since managers are human beings, the efficiency of their judgments is limited. Two major sources of inefficiency in their judgments have been recognized: one is systematic deviations from normatively preferred decisions, so called bias or incorrect intuition, and the other is inconsistency in their judgments, i.e. erratic decision making variance. Rather than bias, variance is really expensive or damaging. Thus, if the inconsistency in managers judgments is removed, performance could be by far improved by virtue of the reduced random variance. One of the approaches to improve managerial judgment is to simply bring managers together by effectively moderating the random variance due to inconsistency. Focusing on combining judgments, this paper addresses many relevant issues such as why combining and how to combine judgments, and suggests methods and models to effectively aggregate subjective judgments. We conduct an experiment to validate the effectiveness of combining judgments over individual judgments. Various combining schemes are also evaluated in terms of their predictive accuracy. Among them, mean bias based weighting scheme turns out the best. However, when available information is not enough to estimate the expertise of judges, simple and robust equal weighting might be more efficient and productive. This urges an imperative future research on the issue of 'how many and which ones to combine from a large set of experts.'

A Case-Based Forecasting System

Lee, HoonYoung 한국경영과학회 1993 한국경영과학회 학술대회논문집 Vol.- No.2

Many business forecasting problems are characterized by infrequent occurrences, a large number of variables, presence of error, and great complexity. Because no forecasting models and tools are effective in handling these problems, managers often use the outcomes of past analogous cases to predict the outcome of the current one. They (1) observe significant attributes in describing a case, (2) identify the past cases similar in these attributes to the current case, and (3) predict the outcome of the current case based on those of the analogous cases identified through some mental simulation and adjustment. This process of forecasting can be termed forecasting-by-analogy. In spite of fairly frequent use of this forecasting process in practice, however, it has not been recognized as a primary forecasting tool, nor applied on a regular basis. In this paper, by automatizing this process using computer models, we develop a case-based forecasting system (CBFS), which identifies relevant cases and applies their outcomes to generate a forecast. We demonstrate the effectiveness of the CBFS in terms of its accuracy in predicting the outcome of the current problem based on the similar cases identified. We compare the forecasting accuracy of the CBFS with that of regression models developed by stepwise procedure under varied simulated problem conditions. The CBFS outperforms regression models in most comparisons. The CBFS could be used as an effective forecasting tool.

발사환경을 고려한 경사거울 장치 설계 및 구조해석을 통한 구조안정성 고찰

김훈영(Hoonyoung Kim),고대호(Daeho Go) 항공우주시스템공학회 2018 항공우주시스템공학회 학술대회 발표집 Vol.2018 No.11

정부출연연구기관의 기관평가에서 목표 모호성의 영향에 관한 연구

구훈영(Hoonyoung Koo) 한국산업경영시스템학회 2020 한국산업경영시스템학회지 Vol.43 No.4

In order to analyze the organizational performance of government-funded research institutes, four independent variables (organization size, organization age, evaluation system, organization location) and goal ambiguity were empirically analyzed. Although there are existing studies on institutional evaluation, which is the organizational performance of government-funded research institutes, there are differences in research in that it is an empirical analysis analyzed from the perspective of goal ambiguity and that the evaluation system, which is the specificity of institutional evaluation, is included in the analysis. As a result of the analysis, organizational location was the only independent variable that had a direct significant effect on organizational performance, and goal ambiguity showed a significant mediating effect for all independent variables. This indicates that goal ambiguity plays an important role in the organizational performance of government-funded research institutes, and to reduce this, increase the size of the organization, pay attention to establishment of the organization for organizational age, and that it is desirable to have an independent research group in the government department for the organization location. In addition, it was supported that the improvement effect of the evaluation system is proceeding in a desirable direction in terms of goal ambiguity.

RFID 도입을 위한 경제성 분석 방안에 관한 연구

구훈영(Hoonyoung Koo) 한국전자거래학회 2010 한국전자거래학회지 Vol.15 No.1

RFID 확산이 어려운 이유 중 하나는 구체적 경제성 분석 방법의 부재라 할 수 있다. 기존문헌 분석과 파급 효과가 큰 택배산업 사례를 통해 RFID 도입에 따른 비용/혜택 분석을 포함한 경제성 분석 방법을 제시하였다. RFID 적용 효과의 기대 수준을 낙관적, 보수적, 비관적으로 정의하여 분석하고, 태그 단가 등에 따른 민감도 분석을 통해 RFID 비용과 RFID 기술 기대 수준에 따른 불확실성을 반영하였다. 본 연구의 결과는 RFID 도입을 위한 의사결정에 기여할 수 있을 것으로 예상된다. The absence of a concrete method for economic analysis is one of the main reasons that the RFID is not so widespread. Through literature survey and a case study of a courier service company we propose a novel method of economic justification including cost and benefit analysis. In order to reflect the uncertainties caused by the RFID technology itself and the estimated investment cost, we propose optimistic, conservative and pessimistic estimations of benefits and a sensitivity analysis of investment costs. This paper may contribute the systematic evaluation of cost and benefit of RFID adoption.

국내 태양광 산업의 중장기 전망에 관한 연구

구훈영(Hoonyoung Koo),민대기(Daiki Min) 한국산업경영학회 2014 경영연구 Vol.29 No.2

최근 우리나라 정부에서는 RPS 제도의 시행과 함께 다양한 지원 정책을 통하여 신재생 에너지의 확산과 보급을 위한 노력을 기울이고 있으며, 태양광 발전은 여러 신재생 에너지 원 중에서도 핵심 기술로 고려되고 있다. 본 논문은 태양광 발전의 확산과 보급 수준을 평가하고 향후 바람직한 발전 방향성을 탐색하는 것을 목적으로 한다. 이를 위하여 우리나라 태양광 산업의 현황, 미래전망 그리고 바람직한 발전 방향에 관하여 46명의 전문가를 대상으로 3차에 걸친 델파이 조사를 수행하였다. 태양광 발전의 보급 수준을 전망함에 있어 전망치의 타당성 확보를 목적으로 델파이조사를 통한 전문가 패널의 정성적 전망과 함께 과거 보급 실적을 기반으로 확산모형을 이용한 정량적 예측을 수행하였다. 과거 실적을 이용한 전망은 전문가 의견 도는 정부 계획에 비하여 낮은 수준을 보이고 있는데, 델파이 조사 결과를 수요, 공급, 기술, 정책의 네 측면에서 심층 분석하여 태양광 산업의 활성화를 위한 주요 이슈와 전제 조건 등을 정리하였다. 마지막으로 전문가 전망에 비하여 미흡한 태양광 발전의 확산ㆍ보급을 활성화하기 위한 정부와 산업계의 정책적 시사점을 제시하였다. The Korean government recently established a Renewable Portfolio Standard (RPS) policy with aims to promote renewable energy technologies (RETs). The purpose of this paper is to evaluate the projections of solar photovoltaic generations, which is the major RET in Korea, and to provide suggestions for promoting solar energy in Korea. We conducted a three-round Delphi survey with a panel of 46 experts. Furthermore, a diffusion model is employed with aims to validate the projections of the installed capacity of solar power. The diffusion model based on the past data reveals that it is hard to assure the success of the initial RPS (i.e., government plan) if we expand the solar photovoltaic generation at the same rate as the past few years. Finally, this study did an in-depth analysis of the Delphi survey and suggested some implications on the direction of the Korean government and industry.

제조업종 연구개발투자의 혁신 및 기업성과에서 공동연구개발과 무형자산의 역할

구훈영(Hoonyoung Koo) 한국산업경영시스템학회 2020 한국산업경영시스템학회지 Vol.43 No.1

The effects of R&D investment on innovation such as patents and intangible assets, and the effect on the corporate performance such as revenue and profit growth, were analyzed using path analysis. In particular, this study compared and analyzed the performances of non-cooperative R&D and cooperative R&D. The results of this study are summarized as follows. First, R&D investment has a significant impact on innovation performance. This supports the existing research results. Second, patents have a significant impact on intangible asset growth. Third, in the case of corporate groups carrying out cooperative R&D, intangible asset growth forms a significant causal relationship with revenue growth. Fourth, in case of cooperative R&D, intangible asset growth has a significant mediating effect between patent and revenue growth. Like the existing research, the results of this research support the innovation performance of R&D investment. It also supports the existing argument that the results of cooperative R&D are more favorable to increase corporate value. However, unlike the existing research, we found a path leading to increased revenue through patents and intangible assets, and confirmed that such a path is likely to be achieved through cooperative R & D rather than internal R&D.

비교대안의 속성수준 분포가 대안평가에 미치는 영향 - 지식수준과 평가방법에 따른 속성분포 정보의 활용 -

이훈영 ( Hoonyoung Lee ),서상윤 ( Sangyun Seo ) 경남대학교 산업경영연구소 2015 지역산업연구 Vol.38 No.3

본 연구에서는 주변대안의 속성수준 분포 맥락이 속성에 대한 평가에 영향을 미칠 수 있음을 범위-빈도이론과 적응수준이론에 기반하여 설명하고자 하였다. 그리고 소비자들이 대안을 평가할 때 제품지식과 평가방법에 따라 활용하는 준거정보에 차이가 있는지도 살펴보고자 하였다. 연구결과 응답자들은 대안을 평가할 때 주변맥락에 상당히 영향을 받음을 보였고, 이는 기존 연구결과와 맥락을 같이한다. 응답자는 대안 평가시 외적 준거(범위와 순위) 정보 뿐 만 아니라 내적준거(분포의 평균)정보를 활용하여 평가하지만 그 설명력에 있어서는 범위와 빈도 준거점 정보를 이용한 소비자 대안평가의 예측력이 평균 정보를 이용한 예측력 보다 더 높았다. 그리고 제품지식 정도에 따라 제품지식이 낮은 소비자들은 분포 범위가 대안평가에 주로 영향을 주었으며, 제품지식이 높은 소비자들은 제품지식이 낮은 소비자들과 비교하여 분포 패턴은 유사하나 전반적인 평가값이 낮게 나타난 것으로 보아 범위와 순위 등 외적준거 뿐 만 아니라 평균값과 같은 내적준거가 대안평가에 영향을 주었을 것으로 보인다. 그리고 대안 평가방식에 따른 준거점 정보의 활용정도는 대안들을 동시에 비교 평가하는 경우 대안을 개별적으로 평가하는 경우 보다 속성의 분포범위가 대안평가에 보다 영향을 미치는 것으로 나타났다. This research intended to investigate how the distribution of contextual stimuli affects the subjective judgment based on the range-frequency theory, and adaptation level theory. In addition, we study that the reference information differs from product knowledge, and evaluation mode. The results suggest several implications that the consumer's judgment to alternatives is likely to depend on the stimuli context, and to stand on the line of previous research findings. The consumer utilized both the external and internal information, but the external information, such as distribution range and ranks, explained the consumer's subjective judgment better than internal information did. In addition, the respondent who has the less product knowledge depended on the information of distribution range, but the more the respondent has product knowledge utilized the more external and internal information of distribution. Also, the utilized information of contextual distribution differs from evaluation mode(simultaneous evaluation, separate evaluation).