Expectational Stability in Multivariate Models

Seonghoon Cho,Antonio Moreno 한국계량경제학회 2008 한국계량경제학회 학술대회 논문집 Vol.2009 No.-

This paper shows that the concept of Expectational stability (E-stability) in a multivariate framework is inherently model-dependent. Whereas a Rational Expectations equilibrium (REE) is subject to model-specific parameter restrictions from the economic model at hand, a perceived law of motion (PLM) is postulated without such restrictions because economic agents are not likely to know the restrictions a priori. Therefore, an unrestricted PLM is in general overparameterized relative to an REE of interest in multivariate models even when the functional form is the same as the REE. Since E-stability necessarily reflects model-specific extents of overparameterization, it is model-dependent as well. Consequently, E-stability is not directly comparable across multivariate models or different representations of a given model. This implies that one may draw different conclusions on E-stability of an REE to one model under alternative representations of the same model and the REE. Our finding is independent of the information structure, the stationarity of solutions or the determinacy of a given model. We provide several economic examples analyzed in the literature. In particular, we show that a fundamental solution to a canonical New-Keynesian model can be E-stable or not depending on representations even in the case of determinacy.

자연이자율, 잠재성장률과 장기 통화정책기조

조성훈(Seonghoon Cho) 한국계량경제학회 2020 JOURNAL OF ECONOMIC THEORY AND ECONOMETRICS Vol.31 No.2

자연이자율은 거시경제가 장기 균형상태에 있을 때 적용되는 실질이자율로서 잠재성장률이 실질 성장률의 추세를 나타내는 것처럼 실질이자율의 장기적 균형을 반영하고, 이론적으로 자연이자율은 잠재성장률과 추세적으로 유사해야 한다. 또한 통화정책당국이 실질이자율에 큰 영향을 미치기 때문에 실질이자율과 자연이자율의 차이는 통화정책당국의 실물부문에 대한 장기적 정책기조를 판단할 수 있는 근거가 될 수 있다. 본 연구는 Holston et al. (2017)의 모형에 근거하여 한국과 미국의 잠재성장률과 자연이자율을 추정한다. 그러나 경제주체가 직면하는 실질이자율은 실질시장이자율로서 전통적인 실질기준금리와 다를 수 있고 또한 인구증가가 있을 때 1인당 총생산이 이론적으로 더 적절한 변수일 수 있다. 본 연구는 이러한 점에 착안하여 위와 같은 대안으로 제시된 변수들과 모형의 조정을 통해 실질기준금리를 이용한 경우와 비교분석한다. 추정결과 실질시장이자율을 사용한 경우가 전통적인 실질기준금리를 사용한 경우보다 자연이자율의 특성을 더 잘 나타낸다는 것을 확인하였다. 또한 2000년대 이후 한국은 실질기준금리가 추정된 자연이자율보다 매우 낮아 통화정책당국의 장기적 기조가 매우 완화적이었을 가능성을 시사한다. The natural rate of interest is the real interest rate that would prevail when the macro economy is in its natural, long-term equilibrium at which the actual GDP growth rate equals its potential rate. The natural rate of interest should therefore comove with the long-term trend of the potential GDP growth. In addition, since monetary policy authority has a significant impact on real interest rates, the difference between real and natural interest rates can be the basis for determining the long-term policy stance for the real sector of the economy. This study estimates potential growth rates and natural interest rates in Korea and the United States based on the Holston et al. (2017) model with important adjustments. We use the real market interest rate faced by economic agents, which may be different from the traditional real rate computed using the policy rate. Also, GDP per capita is considered, which is theoretically more suitable when population growth is taken into account. The estimation results using these new measures and the associated adjustment in the model reveal that the estimated natural rate of interest captures the theoretical characteristics of the natural interest rate better than the estimate using standard real interest rate. In addition, since the 2000s, Korea’s real rate was much lower than the estimated natural interest rate, suggesting that the long-term monetary policy stance in Korea might have been strongly accommodating.

노인의 죽음불안이 자아통합감에 미치는 영향에서 심리적 안녕감의 매개효과

조성훈(Seonghoon Cho) 한국노년학회 2021 한국노년학 Vol.41 No.4

본 연구는 노인의 죽음불안이 자아통합감에 미치는 영향을 알아보고, 죽음불안과 자아통합감의 관계에서 심리적 안녕감의 매개효과를 검증하였다. 이를 위해 서울 및 경기 지역 노인 관련 시설에 거주하는 65세부터 94세까지의 노인 254명을 대상으로 2020년 9월 1일부터 같은 해 11월 30일까지 설문을 시행하였고, 측정도구로는 죽음불안 척도, 심리적 안녕감 척도, 자아통합감 척도를 사용하였고, Baron·Kenny(1986)의 3단계 매개효과 분석 방법을 활용하였다. 연구의 결과는 첫째, 죽음불안이 자아통합감에 미치는 영향력은 통계적으로 유의하였다. 둘째, 적용한 결과, 죽음불안과 자아통합감 간의 관계에서 심리적 안녕감이 완전매개 효과를 갖는 것으로 연구 결과가 나타났다. 이 연구에서는 노인의 자아통합감 문제를 효과적이고 긍정적으로 다루기 위해서는 노인의 죽음불안과 함께 노인의 심리적 안녕감 역시 간과하지 않아야 한다는 것을 밝혔다. This study investigated the effect of death anxiety on the sense of self-integration in the elderly and verified the mediating effect of psychological well-being in the relationship between death anxiety and self-integration. For this study, a questionnaire was conducted from September 1, 2020 to November 30, 2020, targeting 254 elderly people aged 65 to 94 who live in elderly-related facilities in Seoul and Gyeonggi-do. As measurement tools, the death anxiety scale, psychological well-being scale, and self-integration scale were used, and Baron·Kenny (1986) s three-step mediating effect analysis method was used. The results of the study first, The influence of death anxiety on self-integration was statistically significant. Second, the results of using the three-stage mediating effect analysis method proposed by Baron and Kenny (1986), In the relationship between death anxiety and self-integration, psychological well-being was found to have a mediating effect. In conclusion, the results of this study suggest that in order to effectively and positively deal with the elderly s self-integration problem, the elderly s psychological well-being as well as the elderly s death anxiety must not be overlooked.

풍력발전기가 연계된 배전계통에서 사고위치 변화에 따른 사고전류 특성 분석

조성훈(Seonghoon Cho),차한주(Hanju Cha) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.11

최근 신재생에너지 발전 시장은 급격한 성장세를 보이고 있으며, 특히 풍력발전 시장은 2008년 말 이미 120GW 용량의 풍력발전기가 전 세계에 설치되었으며, 이는 2004년말 48GW의 두배 이상에 해당하는 수치이다. 특히, 여러 신재생에너지원 중 풍력발전기는 에너지 변환 효율이 높고, 발전 단가가 싸기 때문에, 앞으로도 다른 신재생에너지원보다 더욱 큰 발전이 기대된다.<SUP>[1]</SUP> 본 논문에서는 PSCAD/EMTDC를 이용하여 2㎿급 이중여자 풍력발전 시스템(DFIG, Doubly-Fed Induction Generator)과 배전계통을 모델링하고 배전계통에서 사고위치 변화에 따른 다양한 고장에 대하여 사례연구를 진행한다.

전국범죄피해조사(Ⅹ) - 범죄피해조사 방법론 연구 -

박성훈(Park, Seonghoon),김민영(Kim, Minyoung),조성현(Cho, Sung-hyun),박희정(Park, Hee-jung),조경호(Cho kyung ho),김영원(Kim, Young-Won),박민규(Park, Mingue),박철현(Cheol-Hyun Park),이명진(Myoung-Jin Lee),임석순(Im, Seok-soon),엄효진( 한국형사법무정책연구원 2020 형사정책연구원 연구총서 Vol.- No.-

Molluscicidal Effect of Eco-Friendly Agricultural Substances for Controlling Golden Apple Snails (Pomacea canaliculata, Lamarck)

( Il Kyu Cho ),( Woo Young Cho ),( In Sun Cho ),( Heon Woong Kim ),( Seonghoon Hyeong ),( Jang Hyun Park ),( Young Sig Kim ),( Kil Yong Kim ),( Gi-woo Hyoung ) 한국환경농학회 2023 한국환경농학회지 Vol.42 No.4

The golden apple snail (Pomacea canaliculata) has been utilized as a natural and eco-friendly control of weeds in rice paddy fields. However, P. canaliculata can damage other crops. In this study, the effectiveness of plant extracts from various natural sources that are reportedly effective against pests in the control of P. canaliculata was investigated. The four plant extracts were effective against P. canaliculata and ranked in descending order as green tea seed (Camellia sinensis) > root of red spider lily (Lycoris radiata) > leaves of tobacco (Nicotiana tabacum) > root of sophora (Sophora flavescens). The mortality rate of P. canaliculata was increased using 200 to 2000 mg/kg of green tea seed powder. However, shrubby sophora root extract did not significantly increase the mortality rate. The LC₅₀ and LC₉₀ of green tea seed, tobacco leaves, shrubby sophora root, and red spider lily root were 900 and 2800 mg/L, 956 and 2320 mg/L, 2162 and 5325 mg/L, and 512 and 1054 mg/kg, respectively. The LC₅₀ and LC₉₀ of ground powder of C. sinensis, N. tabacum, S. flavescens and L. radiata were 248 and 646 mg/L, 403 and 733 mg/L, 409 and 905 mg/L, and 493 and 1141 mg/L, respectively. The findings indicate the remarkable control potency of green tea seeds against the golden apple snail. An organic material incorporating the four plant powders may help control green apple snail in an ecosystem-friendly manner.

Genome Architecture and Transcriptome Analysis of Marine Cyanobacteria Synechocystis sp. PCC 7338

Yujin JEONG,Seong-Joo HONG,Sang-Hyeok CHO,Seonghoon YOON,Hookeun LEE,Hyung-Kyoon CHOI,Dong-Myung KIM,Choul-Gyun LEE,Suhyung CHO,Byung-Kwan CHO 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.4

Cyanobacteria producing various bio-products are considered promising microbial cell factories. The marine cyanobacterium Synechocystis sp. PCC 7338 has the advantage of growing in seawater, rather than requiring arable land or freshwater. However, how this marine cyanobacterium grows under the high salt stress condition remains unknown. Here, we determined the 3.70 Mbp complete genome of Synechocystis sp. PCC 7338. Differential RNA-seq and Term-seq data provided genome-wide information on genetic regulatory elements. Comparison with freshwater Synechocystis sp. strains revealed that Synechocystis sp. PCC 7338 genome encodes additional genes, which facilitate the adaptation to high salt and high osmotic pressure. A cyclic electron transport through photosystem I actively used by Synechocystis sp. PCC 7338 satisfied the demand for ATP under high salt environment. Our comprehensive analyses provide valuable information to discover the various genomic functions and regulations available for engineering Synechocystis sp. PCC 7338.

Soft Contact Transplanted Nanocrystal Quantum Dots for Light-Emitting Diodes: Effect of Surface Energy on Device Performance

Cho, Hyunduck,Kwak, Jeonghun,Lim, Jaehoon,Park, Myeongjin,Lee, Donggu,Bae, Wan Ki,Kim, Youn Sang,Char, Kookheon,Lee, Seonghoon,Lee, Changhee American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.20

<P>To realize the full-color displays using colloidal nanocrystal quantum dot (QD)-based light emitting diodes (QLEDs), the emissive QD layer should be patterned to red (R), green (G), and blue (B) subpixels on a micrometer scale by the solution process. Here, we introduced a soft contact QD-transplanting technique onto the vacuum-deposited small molecules without pressure to pattern the QD layer without any damage to the prior organic layers. We examined the patternability of QDs by studying the surface properties of various organic layers systematically. As a result, we found that the vacuum-deposited 4,4′,4″-tri(<I>N</I>-carbazolyl)triphenylamine (TCTA) layer is suitable for QD-transplanting. A uniform and homogeneous QD patterns down to 2 μm could be formed for all the RGB QDs (CdSe/CdS/ZnS, CdSe@ZnS, and Cd<SUB>1–<I>x</I></SUB>Zn<SUB><I>x</I></SUB>S@ZnS, respectively) with this method. Finally, we demonstrated the R, G, and B QLEDs by transplanting each QD onto the soft TCTA layer, exhibiting higher brightness (2497, 14 102, and 265 cd m<SUP>–2</SUP>, respectively) and efficiency (1.83, 8.07, and 0.19 cd A<SUP>–1</SUP>, respectively) than those of the previous QLEDs fabricated by other patterning methods. Because this pressure-free technique is essential for patterning and stacking the QDs onto the soft organic layer, we believe that both fundamental study and the engineering approach presented here are meaningful for the realization of the colloidal QD-based full-color displays and other optoelectronic devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-20/acsami.5b01738/production/images/medium/am-2015-01738a_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b01738'>ACS Electronic Supporting Info</A></P>

레이저 유도된 스트레쳐블 그래핀-스트레인 센서 기반 웨어러블 스마트 헬스케어 모니터링 시스템

정성훈(Seonghoon Jeong),송혜수(Hyesu Song),최진호(Jinho Choi),이건욱(Geonwook Lee),이안채(Anchae Lee),조용현(Younghyeon Cho),김동균(Dong Kyun Kim),Ashok Chhetry,박재영(Jae Yeong Park) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.7

이요인 일반화부분점수 모형을 위한 공통-문항 기반 다차원 IRT 척도연계 방법

김성훈(Seonghoon Kim),조우정(Woojung Cho) 한국교육평가학회 2020 교육평가연구 Vol.33 No.1

이요인 일반화부분점수(BGPC) 모형은 다차원 문항반응이론(IRT) 모형의 하나로 여러 부분점수로 채점되는 검사 문항의 특성을 일반 요인과 집단-특수 요인으로 분석하고자 할 때 사용할 수 있다. 본 연구의 목적은 BGPC 모형을 위한 공통-문항 기반 척도연계 방법으로 최소제곱(LSQ), 평균-최소제곱(MLS), 문항유목반응함수(IRF) 및 검사반응함수(TRF) 방법 등을 제시하고 모의실험을 통해 이 방법들의 특성과 상대적 기능을 탐구하는 데 있다. 각 척도연계 방법은 공통 문항의 BGPC 모형 모수의 개별 추정(separate calibration)에서 사용된 두 다차원 IRT 능력척도를 연계하기 위해 팽창 계수와 이동 계수를 추정한다. 네 척도연계 방법들의 기능을 평가하기 위해, 선행 연구와 유사하게, 피험자 집단 간 능력의 비동등성 수준, 표본의 크기, 공통 문항의 수 등을 요인으로 포함하는 모의실험을 수행하였다. 주요 결과로, 네 가지 척도연계 방법은 고려된 모의실험 조건 모두에서 팽창 계수를 적절히 추정하였다. 그러나 이동 계수의 추정에 있어서, IRF, LSQ 및 MLS 방법은 적절히 기능한 반면 TRF 방법은 비교적 저조한 수행 결과를 보였다. 척도연계를 통한 능력모수와 문항모수의 복원에 있어서, 전반적으로 IRF 방법이 가장 우수하였고, LSQ 혹은 MLS방법이 그 다음으로 우수하였으며, 일부 조건을 제외하고 TRF 방법이 가장 열등하였다. The bi-factor generalized partial credit (BGPC) model, which is among the polytomous multidimensional item response theory (IRT) models, can be used to analyze the partially scored item response data of bi-factor latent structures. The purpose of this study is to present four scale-linking methods for the BGPC model under the common-item equating/linking design and investigate their characteristics and performances through computer simulations. The four linking methods presented are the least squares (LSQ), mean-least squares (MLS), item-category response function (IRF), and test response function (TRF) methods. The four linking methods estimate the dilation and translation coefficients in linear transformations, with the assumption of independence among all general and group-specific factors. Computer simulations that included three factors of (a) nonequivalence level between two examinee groups, (b) sample size, and (c) number of the common items to be used for linking were conducted to examinee the performances of the four methods. Overall, the four methods properly estimated the dilation coefficients. In estimation of the translation coefficients, however, the IRF, LSQ, and MLS methods functioned properly but the TRF method did not. In the recovery of both ability and item parameters, the IRF method performed best in mose cases, the LSQ or MLS method second best, and the TRF method worst, with few exceptional cases.