Microstructure and Mechanical Properties of AC7A Al Alloy Propeller Fabricated by Electromagnetic Stirring Treatment

Kim, Daehwan,Kim, Seoyeong,Beak, Ahruem,Kim, Sewon,Lim, Sugun American Scientific Publishers 2018 Science Of Advanced Materials Vol.10 No.10

Structural Relationship between Brand Personality of Winter Olympics and Host Nation, Image Fit, and Loyalty

( Daehwan Kim ),( Hany Kim ),( Yihan Huang ),( Jin Jae Kim ) 한국체육학회 2020 International journal of human movement science Vol.14 No.2

The current study assumes that positive brand personality of host nations would be transferred to the brand personality of mega sport events, and thereby affecting consumer behaviors. Additionally, such transferred effects would be amplified depending on the perceived image fit between host nations and mega sport events based on the principle of cognitive congruence effects. Therefore, the purpose of the current study was to examine the effect of the brand personality of host nations on consumer loyalty through the brand personality of mega sport events depending on the perceived image fit between host nations and mega sport events. The results showed that brand personality of host nation did not only positively influenced brand personality of mega sport event, but it also indirectly affected consumer loyalty. Additionally, the image fit between host nations and mega sport events was found to moderate the effect of brand personality of host nations on brand personality of mega sport events. Accordingly, we suggest that practitioners should develop positive brand personality of host nations and mega sport events while considering their image fit.

Symbiotic Relationship Between Sport Media Consumption and Spectatorship: The Role of Flow Experience and Hedonic Need Fulfillment

Daehwan Kim,Amy Kim,Jeeyoon Kim,Yong Jae Ko 글로벌지식마케팅경영학회 2022 Journal of Global Sport Management Vol.7 No.1

When it comes to the relationship between sport media con- sumption (SMC) and sporting event attendance, two contradicting notions have been dominant: symbiosis vs. competition. With a focus on consumers’ hedonic need fulfillment and the psycho- logical concept of flow experience, the current study examined whether SMC stimulates spectatorship (symbiotic relationship). Specifically, we aimed to examine the impact of a personal factor (team identification) and a situational factor (perceived team per- formance) on flow experience and how the flow experience drives attendance intention through hedonic need fulfillment. Data on 386 sport media consumers who watched a 2014 World Cup match on television were collected and analyzed for the study. The results of structural equation modeling (SEM) analysis revealed that both team identification and perceived team per- formance positively influenced flow experience, which in turn sig- nificantly influenced future spectatorship intention through hedonic need fulfillment. Theoretical and managerial implications of the findings are discussed.

Nickel dust-induced occupational contact dermatitis by welding and grinding work in shipyard workers: a report of nine cases

Daehwan Kim,A Ram Kim,Hanjun Kim,Sunghee Lee,Byeonghak Seo,Ho Seok Suh,Chang Sun Sim,Heun Lee,Cheolin Yoo 대한직업환경의학회 2022 대한직업환경의학회지 Vol.34 No.-

Background: Occupational skin diseases are skin conditions that occur or worsen in relation to work and known to be the second most common type of occupational disease affecting individuals in the United States. In Korea, epidemiological reports related to occupational skin diseases are rare. But, no cases of occupational contact dermatitis caused by welding and grinding work have been reported previously. Case presentation: Nine male workers working in the production department for liquefied natural gas (LNG) ships in Ulsan complained of erythematous papules/patches and itching in various areas of the body after welding and grinding work. The work environment monitoring report revealed that the amount of nickel dust exceeded the time weighted average (TWA) and poor local ventilation status. Based on the symptoms and the overall results of surveys, several tests, and work environment monitoring report, the 2 workers who had positive patch-test reactions to nickel were diagnosed with nickel dust-induced allergic contact dermatitis. The other 7 workers were diagnosed that there was a high probability that they had nickel dust-induced irritant contact dermatitis. The 2 workers who had nickel dust-induced allergic contact dermatitis were recommended to switch their jobs. Conclusions: Nickel is one of the most common cause of allergic contact dermatitis. In this case, the dust was assumed to be created by welding work with a high nickel content new welding rod and subsequent grinding work, and the concentration of this dust exceeded the time weighted average. Thus, it is thought that the nickel dust may have caused contact dermatitis through continuous contact with the workers" exposed skin in a poorly ventilated space. Currently, several domestic shipbuilding companies are manufacturing LNG tankers using a new construction method. Consequently, it is highly likely that similar cases will occur in the future, which makes this case report meaningful.

The Protective Effect of Indole-3-Acetic Acid (IAA) on H ₂ O ₂ -Damaged Human Dental Pulp Stem Cells Is Mediated by the AKT Pathway and Involves Increased Expression of the Transcription Factor Nuclear Factor-Erythroid 2-Related Fac

Kim, Daehwan,Kim, Hyewon,Kim, Kichul,Roh, Sangho Hindawi 2017 Oxidative medicine and cellular longevity Vol.2017 No.-

<P>Indole-3-acetic acid (IAA) is the most common plant hormone of the auxin class and is known to have many effects including cell proliferation enhancement and antioxidant property. However, no study has revealed its defensive effects against oxidative toxicity in human dental pulp stem cells (hDPSCs). In this study, we investigated the effects of IAA on hydrogen peroxide- (H<SUB>2</SUB>O<SUB>2</SUB>-) induced oxidative toxicity in hDPSCs. H<SUB>2</SUB>O<SUB>2</SUB>-induced cytotoxicity was attenuated after IAA treatment. Cell cycle analysis using FACS showed that the damaged cell cycle and increased number of apoptotic cells by H<SUB>2</SUB>O<SUB>2</SUB> treatment were recovered after the treatment of IAA. The H<SUB>2</SUB>O<SUB>2</SUB>-mediated increased expression of the proapoptotic genes, <I>BAX</I> and <I>p53</I>, was attenuated by IAA treatment, while IAA treatment increased antiapoptotic genes, <I>BCL-2</I> and <I>ATF5</I> expression. The increases of cleaved caspase-3 and ROS by H<SUB>2</SUB>O<SUB>2</SUB> were also decreased after treatment of IAA. To further investigate the mechanism of IAA, Nrf2-related antioxidant pathway was examined and the results showed that the level of Nrf2 and HO-1 expressions, stimulated by H<SUB>2</SUB>O<SUB>2,</SUB> decreased after treatment of IAA. Moreover, IAA treatment protected hDPSCs against H<SUB>2</SUB>O<SUB>2</SUB>-induced oxidative stress via increased expression of Nrf2 and HO-1, mediated by the AKT pathway.</P>

Analysis of the Recent Research Trends in Image-based 3D Human Shape Estimation

Daehwan Kim,Yongwan Kim,Jinsung Choi,Ki-Hong Kim 한국정보통신학회 2022 2016 INTERNATIONAL CONFERENCE Vol.13 No.1

Epidermal growth factor improves the migration and contractility of aged fibroblasts cultured on 3D collagen matrices

KIM, DAEHWAN,KIM, SO YOUNG,MUN, SEOG KYUN,RHEE, SANGMYUNG,KIM, BEOM JOON UNKNOWN 2015 INTERNATIONAL JOURNAL OF MOLECULAR MEDICINE Vol.35 No.4

<P>Epidermal growth factor (EGF) plays a critical role in fibroblasts by stimulating the production of collagen and supports cell renewal through the interaction between keratinocytes and fibroblasts. It is well known that the contractile activity of fibroblasts is required for the remodeling of the extracellular matrix (ECM), which contributes to skin elasticity. However, the role of EGF in the contraction of aged fibroblasts under 3-dimensional (3D) culture conditions is not yet fully understood. In the present study, we demonstrated that young fibroblasts spread and proliferated more rapidly than aged fibroblasts under 2-dimensional (2D) culture conditions. Cell migration assay using a nested collagen matrix revealed that the migration of young fibroblasts was also greater than that of aged fibroblasts under 3D culture conditions. However, the addition of recombinant human EGF (rhEGF) resulted in the enhanced migration of aged fibroblasts; the migration rate was similar to that of the young fibroblasts. The aged fibroblasts showed decreased cluster formation compared with the young fibroblasts on the collagen matrix, which was improved by the addition of rhEGF. Furthermore, cell contraction assay revealed that the basal contractility of the aged fibroblasts was lower than that of the young fibroblasts; however, following treatment with rhEGF, the contractility was restored to levels similar or even higher to those of the young fibroblasts. Taken together, our results suggest that rhEGF is a potential renewal agent that acts to improve the migration and contraction of aged fibroblasts more efficiently than young fibroblasts under 3D culture conditions; thus, EGF may have valuable regenerative effects on aged skin.</P>

Effects of a supportive workplace environment on the success rate for smoking cessation camp

Kim Woojin,Kim A Ram,Ock Minsu,Jeon Young-Jee,Lee Heun,Kim Daehwan,Kim Minjun,Yoo Cheolin 대한직업환경의학회 2023 대한직업환경의학회지 Vol.35 No.1

Background: This study was conducted to identify the success rate for smoking cessation over time after participation in a therapeutic smoking cessation camp, and to identify how participant characteristics, including a supportive workplace environment for smoking cessation (SWESC), affect the success rate for smoking cessation. Methods: In all, 296 participants at smoking cessation camps in Ulsan between 2015 and 2020 were investigated. The success rates of smoking cessation after weeks 4, 6, 12, and 24 at camp were investigated. The participants were grouped as workers with an SWESC, and workers without an SWESC, and variables (age, education, household income, marital status, drinking, exercise, body mass index, morbidity, job, number of counseling sessions, cigarettes smoked per day and smoking initiation age) were investigated. Multiple logistic regression analysis was conducted at each time point. In addition, Cox regression analysis was performed to evaluate the variables affecting the success rate for smoking cessation over time. Results: The smoking cessation success rate of workers with an SWESC at week 24 (90.7%) was higher than that for workers without an SWESC (60.5%). Multiple logistic regression was performed to determine the relationship between each variable and the success rates for smoking cessation at week 6, 12, and 24. SWESC was confirmed as significant (p < 0.05) variables for increased success rate for smoking cessation at all 3 time points. After adjusting for all variables, the Cox proportional hazards survival analysis showed a hazard ratio of 6.17 for SWESC (p < 0.001,; 95% confidence interval: 3.08–12.38). Conclusions: At a professional treatment smoking cessation camp, participants with an SWESC showed a significantly higher success rate for smoking cessation. Supportive workplace environment for workers’ health is expected to be an important factor for smoking cessation projects as well as other health promotion projects at workplace.

TiO<SUB>x</SUB> ReRAM의 특성 분석 및 DC 컴팩트 모델 개발

김대환(Daehwan Kim),최준혁(Junhyeok Choi),김성준(Sungjun Kim),김형진(Hyungjin Kim),조성재(Seongjae Cho) 대한전자공학회 2020 대한전자공학회 학술대회 Vol.2020 No.8

반복 최근접점와 파티클 필터를 이용한 인간 신체 움직임 추적

김대환(Daehwan Kim),김효정(Hyojung Kim),김대진(Daijin Kim) 한국정보과학회 2009 정보과학회논문지 : 소프트웨어 및 응용 Vol.36 No.12

본 논문은 빠르게 움직이는 인간 신체를 추적할 수 있는 실시간 인간 신체 움직임 추적 알고리듬을 제안한다. 반복 최근접점(Iterative closest point) 알고리듬은 효율적이고 계산량이 적어 실시간 인간 신체 움직임 추적에 적합하지만 잘못된 최근접점(Closest point) 선택으로 인해 국부적 최소점(Local minimum)에 쉽게 빠지게 되어 종종 추적에 실패하게 된다. 이를 극복하기 위해, 반복 최근접점 알고리듬에 움직임 이력(Motion history) 정보를 기반으로 한 파티클 필터 (Particle filter)를 결합한다. 제안하는 인간 신체 움직임 추적은 계층적 트리 구조를 사용함으로써 신체 추적 공간 크기를 줄여주며, 움직임 이력 정보를 이용한 움직임 예측 모델을 사용함으로써 빠른 인간 신체 움직임 추적을 가능하게 한다. 실험결과는 제안하는 인간 신체 움직임 추적이 정확한 추적 성능과 빠른 수렴 속도를 가진다는 것을 보여 준다. This paper proposes a real-time algorithm for tracking the fast moving human body. Although Iterative closest point (ICP) algorithm is suitable for real-time tracking due to its efficiency and low computational complexity, ICP often fails to converge when the human body moves fast because the closest point may be mistakenly selected and trapped in a local minimum. To overcome such limitation, we combine a particle filter based on a motion history information with the ICP. The proposed human body motion tracking algorithm reduces the search space for each limb by employing a hierarchical tree structure, and enables tracking of the fast moving human bodies by using the motion prediction based on the motion history. Experimental results show that the proposed human body motion tracking provides accurate tracking performance and fast convergence rate.