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현금배당 공시사건이 주가수익률에 미치는 비대칭적 영향에 관한 연구 : 행태재무적 관점에서
조정호(JungHo Jo),정찬식(ChanShik Jung) 한국산업경영학회 2016 經營硏究 Vol.31 No.2
본 연구는 현금배당의 증가 / 유지, 그리고 현금배당의 감소라는 경제적 사건을, 행태재무의 한 개념인 손실회피(loss aversion)라는 관점에서 실증적으로 분석한다. 이러한 손실회피 현상 하에서 는, 투자자가 배당의 증가 / 유지 공시 때 보다는 배당의 감소 공시 때 더 민감하게 반응하는 것이 가능하다. 이를 고려한 본 연구의 실증결과는 다음과 같다. 첫째, 배당 증가율(변화율)은 배당공시 관련 누적초과수익률과 유의한 양의 관계가 있었다. 둘째, 직전 사업연도와 비교하여 주당 배당액이 1원 감소할 때 누적초과수익률의 하락폭은, 주당 배당액 이 1원 증가할 때 누적초과수익률의 상승폭보다 10배 이상 컸다. 이러한 발견은 앞서 언급한 손실 회피 가설이 성립함을 의미한다. 즉, 1995년부터 2013년까지 KOSPI 시장에 상장된 주식에 투자한 투자자는 배당공시와 관련하여 배당 증가 / 유지라는 긍정적인 뉴스보다는 배당감소라는 부정적인 뉴스에 더욱 민감하게 반응한다는 것을 알 수 있다. 이러한 사실은 기업 배당정책에 임하는 경영진에게 정책적 시사점을 제공하며, 배당공시의 비대칭적 반응을 연구한 선행연구가 존재하지 않았다는 점에서 학문적 시사점을 제공한다 할 수 있다. This study analyzes the stock market performance of firms, which announce the increase, the decrease, or the maintenance of dividends, in view of the loss aversion. The loss aversion is one of concepts in the behavioral finance literature. If the loss aversion is true, investors of a stock market will react more sensitively to the decrease of dividends than to the increase/maintenance of dividends. We find that, at first, the cumulative abnormal returns tend to increase with the increasing/ maintaining dividend announcement. We also find that, adversely, the cumulative abnormal returns tend to decrease with the decreasing dividend announcement. These results are based on the symmetric response of investors. However, more importantly, we find that the asymmetric response of investors tend to exist in the Korean stock market. In detail, we find that the absolute value of the dropped cumulative abnormal returns of firms, which announce the increasing/maintaining dividends, are much greater than the absolute value of the arisen cumulative abnormal returns of firms which announce the decreasing dividends, as the dividend per share changes in comparison to the previous fiscal year. These results support the loss-aversion hypothesis. These findings suggest that the managers of firms should carefully consider the negative effect of the decreasing dividend announcement. Moreover, this study has a contribution in that there has been little literature which consider the asymmetric effect of dividend announcement.
Research on Fatigue Strength of Aluminum Arc Weldment for Automotive Industry Part 3. T-joint
Jungho Cho,Hansol Kim,Seungcheol Shin,Hojin Yoo,Gunho Lee,Jongho Jeon,Minsoo Kim,Youngrae Jo 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Portion of aluminum in car body increases because of mass reduction request due to global environmental problems. However, there is a picky prerequisite in using aluminum to car body because it has low arc weldability caused by low viscosity and surface tension. In these days, this welding problem seems almost solved thanks to the advances in welding machines and related techniques. Another important obstacle in using aluminum is that there are rare aluminum weldment fatigue assessment reports. The number of related literature that can be found in internet is just below 10. Moreover, most of them are not considering various weldment shape itself. This research is about fatigue strength assessment of aluminum arc T-joint fillet welding. This is the last report of a series of aluminum arc welding fatigue assessment. The previous ones are for butt joint and lap joint fillet weld. Target material is 6061-T6 aluminum sheets which are widely used in automotive industry for body structure. Thickness of the sheets is 4mm and the weldments are made with T-joint fillet arc welding. Focused factors in the weldments are penetration depth, gap between the sheets and toe angle. Fatigue strengh of the weldment is assessed with these various weld shape factors. Fatigue experiments are conducted with 5 tons fatigue test machine. SR(stress ratio) value was 0.1 and the vibration frequency was 20Hz. The maximum number of repeated loading cycle was 500,000. Various levels of tensile load applied to the specimens. Totally 5 specimens are experimented for one condition and their average fatigue strength is computed then depicted as S-N curve. The ideal condition for higher fatigue strength is larger toe angle with full penetration. The results also shows same trend, but the effect of toe angle is not stronger than gap and penetration depth. It means that control of gap and penetration depth is more important than controlling toe angle in fatigue strength perspective. One peculiar phenomenon observed through the assessment is the effect of the pores inside the weld. Generally it is known that the pores lower the tensile strength, however it is observed that the pores almost did not affect on the fatigue strength. Several cases even showed higher fatigue strengh for higher porosity. It seems that the pores play a role of crack stop hole in general fatigue crack problem.
Ryu, Jungho,Kim, Soonhyun,Kim, Hyung Il,Jo, Eun-Hee,Kim, Young Kwang,Kim, Minsun,Jang, Hee Dong Elsevier 2015 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.262 No.-
<P><B>Abstract</B></P> <P>Spherical TiO<SUB>2</SUB> agglomerates incorporated with reduced-graphene oxide (rGO) sheets were fabricated using aerosol assisted self-assembly. Compared to that of conventional graphene–TiO<SUB>2</SUB> composites, the new hybrid geometry of the self-assembled agglomeration of TiO<SUB>2</SUB> and rGO enabled a porous structure, a more efficient charge separation through interconnected TiO<SUB>2</SUB> nanoparticles and rGO, and improved the contact between TiO<SUB>2</SUB> and rGO to maximize the role of rGO as an electron reservoir. The as-prepared rGO–TiO<SUB>2</SUB> composites were characterized with a diverse range of analytical techniques, and their photocatalytic activity was tested in terms of H<SUB>2</SUB> production and gaseous CH<SUB>3</SUB>CHO degradation. The incorporation of the rGO sheets into the TiO<SUB>2</SUB> agglomerates promoted the photocatalytic H<SUB>2</SUB> production and CH<SUB>3</SUB>CHO oxidation; our results showed that the performance of our systems is directly proportional to the content of rGO (when added up to 10wt%). This finding confirmed that rGO, acting as an electron collector and mediator, can facilitate charge-pair separation; only a small light-shielding effect by rGO was observed. Furthermore, open-circuit potential decay measurements revealed that the presence of rGO in the agglomerated TiO<SUB>2</SUB> can significantly suppress charge recombination; this further confirmed the role of rGO as an effective electron conduit. The new geometry of the rGO–TiO<SUB>2</SUB> composite proposed in this work shows several advantages compared to various types of graphene–TiO<SUB>2</SUB> composites previously reported, such as the stronger electronic coupling between rGO sheets and TiO<SUB>2</SUB>, minimized light-shielding effect by rGO (even when a relatively large amount of rGO is used), and facile scale-up for mass production. Therefore, our rGO–TiO<SUB>2</SUB> composite can be considered as a promising hybrid photocatalyst for solar energy conversion.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed new hybrid geometry of TiO<SUB>2</SUB> and reduced-graphene oxides. </LI> <LI> The new geometry of the rGO–TiO<SUB>2</SUB> was prepared by the self-assembled agglomeration. </LI> <LI> The rGO–TiO<SUB>2</SUB> composite exhibited the enhanced photocatalytic activity. </LI> <LI> The new geometry would be responsible for minimized light-shielding effect of rGO. </LI> <LI> The rGO–TiO<SUB>2</SUB> composite can be considered as a promising hybrid photocatalyst. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
알루미늄 맞대기 아크 용접부 형상이 피로강도에 미치는 영향
조정호(Jungho Cho),백성진(Sungjin Baek),신승철(Seungchul Shin),이건호(Gunho Lee),강문구(Mun-Gu Kang),조영래(Young-Rae Jo) 대한용접·접합학회 2021 대한용접·접합학회지 Vol.39 No.1
The use of aluminum in auto odies is increasing due to the requirement of mass reduction for gas mileage enhancement. However, few open studies have been conducted on the fatigue strength of arc welded aluminum butt joints. In this study, the fatigue strength of arc welded butt joints of aluminum sheets was investigated. The material was 6061-T6 with a thickness of 4 mm. Welding specimens were prepared to determine the effects of the top bead toe angle, penetration depth, top surface misalignment, and alternative double-butt joint formation. Results showed that the top surface misalignment and partial penetration were more critical than the top bead toe angle on fatigue strength. Partial and full penetration revealed the lowest and highest fatigue strength, respectively. Because of the low viscosity and surface tension, achieving full penetration in butt joint aluminum arc welding without a backing component while also controlling penetration depth are impossible. An alternative solution to this problem is to apply a double-butt joint design, with experimental results showing for the first time the validity of this solution in terms of fatigue strength.
Cha, Jungho,Hwang, Jung-Min,Jo, Hang Joon,Seo, Sang Won,Na, Duk L.,Lee, Jong-Min Hindawi Publishing Corporation 2015 BioMed research international Vol.2015 No.-
<P>Resting-state functional magnetic resonance imaging (RS FMRI) has been widely used to analyze functional alterations in amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) patients. Although many clinical studies of aMCI and AD patients using RS FMRI have been undertaken, conducting a meta-analysis has not been easy because of seed selection bias by the investigators. The purpose of our study was to investigate the functional differences in aMCI and AD patients compared with healthy subjects in a meta-analysis. Thus, a multimethod approach using regional homogeneity, amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), and global brain connectivity was used to investigate differences between three groups based on previously published data. According to the choice of RS FMRI approach used, the patterns of functional alteration were slightly different. Nevertheless, patients with aMCI and AD displayed consistently decreased functional characteristics with all approaches. All approaches showed that the functional characteristics in the left parahippocampal gyrus were decreased in AD patients compared with healthy subjects. Although some regions were slightly different according to the different RS FMRI approaches, patients with aMCI and AD showed a consistent pattern of decreased functional characteristics with all approaches.</P>
Cell-free 다중안테나 다운링크 네트워크에서 딥러닝기반 송신전력 할당 기술 성능분석 연구
명정호(JungHo Myung),김근영(Keunyoung Kim),고영조(Young-Jo Ko) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.11
본 논문에서는 총 송신전력이 제한된 Cell-free 다중안테나 다운링크 네트워크에서 AP 별 효율적 전력제어 기법을 수행하기 위한 딥러닝기반 전력할당 기법을 제안하였고, 그에 따른 성능 분석을 수행하였다. 제안된 기법은 각 AP 에서 SLNR 을 이용한 예측 전송용량을 기반으로 딥러닝 학습을 통해 각 AP 별 송신전력을 결정하는 것을 특징으로 한다. 딥러닝 신경망 학습을 위해 지도학습을 사용하였으며, 학습에 사용한 데이터는 사전에 완전 탐색(full-search)을 기반으로 얻은 AP 송신전력 데이터 값을 사용하였다. 제안된 기법은 네트워크가 가용할 수 있는 총 송신전력량이 작거나 동일한 주파수에서 지원하는 사용자 수가 적을 경우, 기존 기술 대비 전송용량 이득값이 크게 나타나는 것을 확인할 수 있다.