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.

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.

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.

The Use of Oyster Shell Powders for Water Quality Improvement of Lakes by Algal Blooms Removal

Huh, Jae-Hoon,Choi, Young-Hoon,Lee, Hyun-Jae,Choi, Woo Jeong,Ramakrishna, Chilakala,Lee, Hyoung-Woo,Lee, Shin-Haeng,Ahn, Ji-Whan The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.1

In this year, Koreans have a shortage in agricultural and drinking water due to severe algal blooms generated in major lakes. Waste oyster shells were obtained from temporary storage near the workplace at which oysters were separated from their shells. Heating ($1000^{\circ}C$ for 1 h in air) was employed to convert raw oyster shell powders into calcium oxide powders that reacted efficiently with phosphorus and nitrogen to remove algal blooms from eutrophicated wastewater. As the dispersed amount of heated oyster shell powders was increased, water clarity and visual light penetration were improved. Coagulation, precipitation and carbonation process of the heated oyster shell powders in a water purifier facilitated removal of eutrophication nutrient such as phosphorus and nitrogen, which is both beneficial and economically viable. $CO_2$ implantation by carbonation treatment not only produced thermodynamically stable CaO in oyster shells to derive precipitated calcium carbonate (PCC) but also accelerated algal removal by activation of coagulation and precipitation process. The use of oyster shell powders led to a mean reduction of 97% in total phosphate (T-P), a mean reduction of 91% in total nitrogen (T-N) and a maximum reduction of 51% in chemical oxygen demand (COD), compared with the total pollutant load of raw algal solution. Remarkable water quality improvement of algal removal by heated oyster shell powders and PCC carbonation treatment will allow utilization as water resources to agricultural or industrial use.

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

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.

Subcellular distribution of chromogranins A and B in bovine adrenal chromaffin cells

Huh, Yang Hoon,Bahk, Sook Jin,Ghee, Jung Yeon,Yoo, Seung Hyun Elsevier 2005 FEBS letters Vol.579 No.23

<P><B>Abstract</B></P><P>The major secretory granule proteins chromogranins A (CGA) and B (CGB) have recently been shown to play critical roles in inositol 1,4,5-trisphosphate-dependent intracellular Ca<SUP>2+</SUP> mobilizations. We determined here the subcellular distribution of CGA and CGB based on 3D-images of chromaffin cells, and found that ∼95% of cellular CGA was present in secretory granules while ∼5% was in the endoplasmic reticulum (ER), whereas ∼57% of cellular CGB was in secretory granules while ∼24% and ∼19% were in the ER and nucleus, respectively. These results suggest that chromogranins are at the center of intracellular Ca<SUP>2+</SUP> homeostasis in secretory cells.</P>

Testicular Development and Sperm Migration in the Oriental Tobacco Budworm, Helicoverpa assulta (Lepidoptera, Noctuidae)

Huh, Yang Hoon,Lim, Do-Sun,Chung, Kyung Hwun,Kwon, Sun Bang,Jeong, Moon Jin,Jeong, Seong Eun,Yoo, Chong Myong 한국곤충학회 2001 Entomological Research Vol.31 No.2

담배나방의 정소와 상부수정관의 발생 및 정소에서의 정자 이동 양상을 구조 분석을 통해 연구하였다. 각 콩 모양의 유충 정소는 interfollicular septa에 의해 구획되는 4개의 소엽으로 이루어져 있으며, 두 개의 유충 정소는 전용기에 총 8개의 소엽으로 이루어지는 단일 정소로 융합된다. 정소의 융합 직후 비틀림 작용이 일어나 구형의 용-성충기 정소가 형성된다. 정소의 발생동안 정소 내 각 소엽들은 정문으로 집중되는 수정세관들을 통해 상부수정관과 연결된다. 성충기 정소의 상부수정관 벽은 잘 발달된 상피세포들과 이를 감싸는 얇은 단일 근육층으로 이루어져있다. 용 기간 동안 나비목 곤충에서 전형적으로 나타나는 eupyrene정자와 apyrene 정자들이 각 포낭 내에서 분화된다. 사정이 개시됨에 따라 apyrene 포낭들이 eupyrene 포낭들 보다 먼저 정소의 기저막을 통과하며, 이때 apyrene정자들은 포낭으로부터 분리된다. 방출된 eupyrene 정자들은 두꺼운 신월형 외막을 새로이 획득하고, reticular appendage를 계속 지니나 lacinate appendage들은 모두 소실된다. 이상의 형태학적 결과들로 미루어, apyrene정자들이 eupyrene 정자가 정소로부터 수정관으로 이동하는 것을 촉진하는 것으로 판단된다. Developmental profiles of testis and upper vas deferens and aspects of sperm migration from testis in the oriental tobacco budworm, Helicoverpa assulta were investigated through fine structural analysis. The larval testes are bean-shaped, and each one consists of four follicles comparted by interfollicular septa. The two larval testes are fused into a single one consisting of eight follicles at prepupal stage. A torsion force generates in the fused testis immediately lifter the fusion, resulting in a spherical pupal-adult testis. During the testicular development, each intratesticular follicle is connected with upper vas deferens via vas efferens converged at the hilum. In adult, the membranes of upper vas deferens consist of well developed epithelial cells and a thin outer muscle layer. Typical lepidopteran eupyrene and apyrene sperms are differentiated in each of their cysts during pupal development. At ejaculation stage, the apyrene cysts penetrate the basement membrane earlier than eupyrene cysts, and the apyrene sperms are free of their cysts in vas deferens during the penetration. The released eupyrene sperms acquire a new thick coat in crescent shape, and still retain the proper reticular appendages, but lose all the lacinate appendages in vas deferens. From our morphological results, it is considered that the apyrene sperm may facilitate the migration of the eupyrene sperm from the testis to the vas deferens.

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>