복합하중조건에서 AHSS 점용접부의 준정적 파단특성 연구

하지웅(Jiwoong Ha),허훈(Hoon Huh),이홍우(Hongwoo Lee),김교성(Kyo-seong Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

This paper is concerned with the failure characteristic and the failure load of spot welds of AHSS under combined axial and shear loading conditions. The testing fixture and the specimen are newly designed to impose the pure-shear load on a spot weld. The testing fixture and the specimen proposed Song and Huh1 are used to impose the combined axial and shear load from 0° to 75° on spot welds. Using those testing fixture and specimens, failure tests of the spot weld of 590TRIP 1.2t, 780DP 1.0t, and 980DP 1.2t are conducted with seven different combined loading conditions. Based on the experimental results, failure loads and failure behaviors of the spot weld are investigated with respect to different loading angles. Failure loads of the spot weld obtained from failure tests are interpolated to construct Song and Huh’s failure model1, which facilitates the failure description of spot welds in the macroscopic finite element analysis of auto-body structure.

전단 인장 시험을 이용한 점용접부 파단모델 구성

하지웅(Jiwoong Ha),김유종(Yujong Kim),허훈(Hoon Huh),임지호(Jiho Lim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

This paper propose an alternative methodology to construct the dynamic failure model of a spot weld under combined loading conditions for auto-body crash analyses using cross-tension and lap-shear tests. In order to construct the failure model proposed by Song and Huh, failure tests of spot welds should be carried out at intervals of 15˚ from 0˚ to 90˚ or cross-tension and pure-shear tests. But this methodology is not practical because of too difficult and a large number of experiments. In order to substitute lap-shear tests for pure-shear tests, correlation equation between failure loads of pure-shear and lap-shear tests is derived from stress distribution that was assumed around a nugget at failure of a spot weld. Using failure loads of lap-shear and cross-tension tests and β-norm 1.45, Song and Huh’s dynamic failure model of a spot weld is constructed simply. With the failure model which is constructed by the alternative methodology, FE analyses in which are failure loads and failure behaviors of the spot weld are investigated carried out.

Accuracy Analysis of Anisotropic Yield Functions based on the Root-Mean Square Error

Hoon Huh,Yanshan Lou,Gihyun Bae,Changsoo Lee 한국소성가공학회 2010 기타자료 Vol.2010 No.6

This paper evaluates the accuracy of popular anisotropic yield functions based on the root-mean square error (RMSE) of the yield stresses and the R-values. The yield functions include Hill48, Yld89, Yld91, Yld96, Yld2000-2d, BBC2000 and Yld2000-18p yield criteria. Two kind steels and five kind aluminum alloys are selected for the accuracy evaluation. The anisotropic coefficients in yield functions are computed from the experimental data. The downhill simplex method is utilized for the parameter evaluation for the yield function except Hill48 and Yld89 yield functions after the error functions are constructed. The yield stresses and the R-values at every 15°from the rolling direction (RD) and the yield stress and R-value at equibiaxial tension conditions are predicted from each yield function. The predicted yield stresses and R-values are then compared with the experimental data. The root-mean square errors (RMSE) are computed to quantitatively evaluate the yield function. The RMSEs are calculated for the yield stresses and the R-values separately because the yield stress difference is much smaller that the difference in the R-values. The RMSEs of different yield functions are compared for each material. The Hill48 and Yld89 yield functions are the worst choices for the anisotropic description of the yield stress anisotropy while Yld91 yield function is the last choice for the modeling of the R-value directionality. Yld2000-2d and BBC2000 yield function have the same accuracy on the modeling of both the yield stress anisotropy and the R-value anisotropy. The best choice is Yld2000-18 yield function to accurately describe the yield tress and R-value directionalities of sheet metals.

Developing Athletes' Self-Management Model

Huh, Jung-Hoon,Choi, Jae-Won 한국스포츠심리학회 2003 한국스포츠심리학회지 Vol.14 No.3

본 연구는 선행연구를 바탕으로 가설화된 운동선수 자기관리 이론적 모형을 검증하는데 그 목적이 있다. 구체적으로 운동선수 자기관리 4개 하위요인 중 몸관리, 정신관리, 훈련관리는 자신감에, 대인관리는 팀단합에 긍정적 영향을 미치고, 자신감과 팀단합은 중재변인으로서 운동수행에 영향을 미칠 것이다 라는 가설을 수립하고 이를 검증하였다. 수립된 모델 검증을 위해 329명의 전국체전 참가선수들을 조사하였다. 육상, 수영, 양궁, 배드민턴, 복싱, 레슬링, 태권도, 농구, 배구 등 총 20개 종목에 참여한 선수들은 남녀 각각 171명과 158명이었다. AMOS를 사용한 구조방정식 모형 검증결과 가설화된 모형은 양호한 적합도 지수를 나타냈다: GFI=.96, CFI=.95, RMR=.035. 이러한 적합도 지수는 성, 종목, 수준별로 검증한 결과에서도 승인되었다. 구체적으로 살펴보면 몸관리와 정신관리는 자신감에, 자신감은 운동수행에 긍정적인 영향을 미쳤다. 또 대인관리는 팀단합에 긍정적인 영향을 미쳤지만 팀단합은 수행에 유의한 영향을 미치지 못하였다. 또한 훈련관리는 자신감에 부정적인 영향을 미쳤다. 이는 연구자가 설정한 가설을 전체적으로 지지하였으나 일면 상이한 결과를 나타내고 있다. The purpose of this study is to prove the theoretical models on the self-management of athletes by applying a covariance structure analysis. The first hypothesis to verify in this study is whether physical, mental, and training management significantly influence confidence. The second hypothesis is to examine whether interpersonal management has a direct influence on the team's unity. The third hypothesis is to verify that confidence has significant effects on performance level, whereas team unity does not. The fourth hypothesis states that the theoretical model on the self-management of athletes will show an appropriate level of reliability. Finally, the last hypothesis states that the established model will show the appropriateness of the verification dassified by event and level. The 329 participants who participated in the 81st National Athletic Meet held in Pusan, October, 2000 were selected from high schools, colleges, and professional teams based in Seoul, Incheon, and Kyeonggi for this research. The average age was 20.36 years (SD=3.99). The instrument of measurement in this research was ASMQ(Athletics'Self-Management Questionnaire), Self-Confidence and Team unity. The 4.01 WINDOWS version of the AMOS (Analysis of Moment Structure) was used for these serial procedures. The hypothesized cause and effect model for 329 athletes revealed a good fit index and was approved in the test of the model by groups (GFI=96, CFI=95, RMR=.035). In the specific hypothesized path, physical management and mental management had a positive effect on self-confidence which, in turn, affected performance. And interpersonal management affected team integrity positively, which did not significantly affect performance. However, training management had a negative influence on self-confidence. These results generally supported the hypotheses but there were some differences

PAF Antagonistic Activity of 2-hydroxy-3-methoxybenzoic Acid Glucose Ester from Gentiana scabra

Huh, Hoon,Kim, Hye-Kyong,Lee, Hern-Ku The Pharmaceutical Society of Korea 1998 Archives of Pharmacal Research Vol.21 No.4

In order to find out anti-platelet activating factor (PAF) from natural resources, Korean medicinal plants used for the treatments of peripheral circulation disorders were tested for their possible protective effects on PAF-induced anaphylactic shock. From the above screening, the methanol extract of Gentiana scabra showed a potent antagonistic activity against PAF. Water suspension of the extract was partitioned with $CH_2$$CI_2$ and EtOAc, successively. The EtOAc fraction which showed the highest activity was chromatographed on silica gel to yield 6 fractions. From the fraction which showed higher PAF-antagonistic activity than the other fractions, compound 1 was isolated by recrystallization. On the basis of spectral data, compound 1 was identified as 2-hydroxy-3-methoxybenzoic acid glucose ester. The compound prevented the mice from the PAF-induced death at a dose of 300 $\mu\textrm{g}$/mouse.

Control of Algal Blooms in Eutrophic Water Using Porous Dolomite Granules

Huh, Jae-Hoon,Choi, Young-Hoon,Lee, Shin Haeng,Cheong, Sun Hee,Ahn, Ji Whan The Korean Ceramic Society 2017 한국세라믹학회지 Vol.54 No.2

The use of aluminum-based coagulants in water pretreatment is being carefully considered because aluminum exposure is a risk factor for the onset of Alzheimer's disease. Lightly burned-dolomite kiln dust (LB-DKD) was evaluated as an alternative coagulant because it contains high levels of the healthful minerals calcium and magnesium. An organic pore forming agent (OPFA) was incorporated to prepare porous granules after OPFA removal through a thermal decomposition process. A spray drying method was used to produce uniform and reproducible spherical granules with low density, since fine dolomite particles have irregular agglomeration behavior in the hydration reaction. The use of fine dolomite powder and different porosity granules led to a visible color change in raw algae (RA) containing water, from dark green to transparent colorlessness. Also, dolomite powders and granules exhibited a mean removal efficiency of 48.3% in total nitrogen (T-N), a gradual increase in the removal efficiency of total phosphorus (T-P) as granule porosity increased. We demonstrate that porous dolomite granules can improve the settling time and water quality in summer seasons for the emergent treatment of excessive algal blooms in eutrophic water.

The Effects of TWEAK, Fn14, and TGF-$\beta1$ on Degeneration of Human Intervertebral Disc

Huh, Hoon,Lee, Yong-Jik,Kim, Jung-Hee,Kong, Min-Ho,Song, Kwan-Young,Choi, Gun The Korean Neurosurgical Society 2010 Journal of Korean neurosurgical society Vol.47 No.1

Objective: The purpose of this study is to explain the effect and reciprocal action among tumor necrosis factor (TNF) like weak inducer of apoptosis (TWEAK), fibroblast growth factor-inducible 14 (Fn14), and transforming growth factor-$\beta1$ (TGF-$\beta1$) on degeneration of human intervertebral disc (IVD). Methods: Human intervertebral disc tissues and cells were cultured with Dulbecco's Modified Eagle's Medium/Nutrient F-12 Ham (DMEM/F-12) media in $37^{\circ}C$, 5% $CO_2$ incubator. When IVD tissues were cultured with TWEAK, Fn14 that is an antagonistic receptor for TWEAK and TGF-$\beta1$, the level of sulfated glycosaminoglycan (sGAG) was estimated by dimethyl methyleneblue (DMMB) assay and sex determining region Y (SRY)-box 9 (Sox9) and versican messenger ribonucleic acid (mRNA) levels were estimated by reverse transcriptase polymerase chain reaction (RT-PCR). Results: When human IVD tissue was cultured for nine days, the sGAG content was elevated in proportion to culture duration. The sGAG was decreased significantly by TWEAK 100 ng/mL, however, Fn14 500 ng/mL did not change the sGAG production of IVD tissue. The Fn14 increased versican and Sox9 mRNA levels decreased with TWEAK in IVD tissue TGF-$\beta1$ 20 ng/mL elevated the sGAG concentration 40% more than control. The sGAG amount decreased with TWEAK was increased with Fn14 or TGF-$\beta1$ but the result was insignificant statistically. TGF-$\beta1$ increased the Sox9 mRNA expression to 180% compared to control group in IVD tissue. Sox9 and versican mRNA levels decreased by TWEAK were increased with TGF-$\beta1$ in primary cultured IVD cells, however, Fn14 did not show increasing effect on Sox9 and versican. Conclusion: This study suggests that TWEAK would act a role in intervertebral disc degeneration through decreasing sGAG and the mRNA level of versican and Sox9.

Testing an Empirical Model for the Value Network of the Mobile Communication Industry in Korea

Hoon Huh,Dohan Song,Sung Hwee Lee 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.2

The mobile communication industry evolves into a mobile communication industry ecosystem led by new keystone players (i.e., Apple and Google) and reflects the expansion of overall industrial competitiveness in size through conversion with other businesses. In this study, the modeling was done in a systematic method to derive the answers to the questions such as, which functions in the value chains of mobile communication industry contribute most to profit creation, what is the key resource, and what the new business model is. This study attempts to objectively identify derivation of factors and correlations between the configuration factors for competitiveness expansion for each industry. Specifically, we developed a dynamic model to predict the overall industry movement by theoretically establishing the modelling concept about value networking of the mobile communication industry ecosystem. Using the system dynamics methodology, coupled with professional interviews, this paper empirically tests the value network model that reflects open mobile communication ecosystem. The results show that the ecosystem of the mobile communication industry is evolving into an open form with the surfacing of portals and terminal production companies, suggesting the collapse of the traditional structure (Walled Garden).

Influence of Uncertainty in Moving Follower Force on Heteroparametric Instability of a Non-Autonomous System

Hoon Huh,Tai Young Ahn 대한기계학회 1987 Asia-Pacific Vibration Conference Vol.1 No.1

Higher 5-hydroxymethylcytosine identifies immortal DNA strand chromosomes in asymmetrically self-renewing distributed stem cells

Huh, Yang Hoon,Cohen, Justin,Sherley, James L. National Academy of Sciences 2013 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.110 No.42

<P>Immortal strands are the targeted chromosomal DNA strands of nonrandom sister chromatid segregation, a mitotic chromosome segregation pattern unique to asymmetrically self-renewing distributed stem cells (DSCs). By nonrandom segregation, immortal DNA strands become the oldest DNA strands in asymmetrically self-renewing DSCs. Nonrandom segregation of immortal DNA strands may limit DSC mutagenesis, preserve DSC fate, and contribute to DSC aging. The mechanisms responsible for specification and maintenance of immortal DNA strands are unknown. To discover clues to these mechanisms, we investigated the 5-methylcytosine and 5-hydroxymethylcytosine (5hmC) content on chromosomes in mouse hair follicle DSCs during nonrandom segregation. Although 5-methylcytosine content did not differ significantly, the relative content of 5hmC was significantly higher in chromosomes containing immortal DNA strands than in opposed mitotic chromosomes containing younger mortal DNA strands. The difference in relative 5hmC content was caused by the loss of 5hmC from mortal chromosomes. These findings implicate higher 5hmC as a specific molecular determinant of immortal DNA strand chromosomes. Because 5hmC is an intermediate during DNA demethylation, we propose a ten-eleven translocase enzyme mechanism for both the specification and maintenance of nonrandomly segregated immortal DNA strands. The proposed mechanism reveals a means by which DSCs “know” the generational age of immortal DNA strands. The mechanism is supported by molecular expression data and accounts for the selection of newly replicated DNA strands when nonrandom segregation is initiated. These mechanistic insights also provide a possible basis for another characteristic property of immortal DNA strands, their guanine ribonucleotide dependency.</P>