국부좌굴이 발생하는 H-형강 휨부재의 강도에 관한 연구

서건호,서상정,권영봉,Seo, Gun-Ho,Seo, Sang-Jung,Kwon, Young-Bong 한국강구조학회 2011 韓國鋼構造學會 論文集 Vol.23 No.6

This paper describes the moment capacity of flexural members with local buckling based on a series of FE and experiment results. Thin-walled flexural members undergo local, lateral-torsional, or interactive buckling according to the section geometries and lateral boundary conditions. Flexural members with large width-to-thickness ratios in the flanges or the web may undergo local buckling before lateral-torsional buckling. Local buckling has a negative effect on the flexural strength based on the lateral-torsional buckling of flexural members. This phenomenon should be considered in the estimation of the flexural strength of thin-walled sections. Flexural members with various width-to-thickness ratios in their flanges and web were analyzed. Initial imperfections in the local buckling mode, and residual stresses, were included in the FE analyses. Simple bending moment formulae for flexural members were proposed based on the FE and test results to account for local and lateral-torsional buckling. The proposed bending moment formulae for the thin-walled flexural members in the Direct Strength Method use the empirical strength formula and the grosssection modulus. The ultimate flexural strengths predicted by the proposed moment formulae were compared with the AISC (2005), Eurocode3 (2003), and Korean Highway Bridge Design Specifications (2010). The comparison showed that the proposed bending moment formulae can reasonably predict the ultimate moment capacity of thin-walled flexural members. 본 논문에는 국부좌굴이 발생하는 휨부재의 유한요소해석 및 실험에 근거한 단면의 휨강도에 대하여 기술하였다. 박판으로 구성된 휨부재는 단면조건 및 횡방향 경계조건에 따라서 국부좌굴, 횡-비틀림좌굴 및 두 좌굴의 혼합좌굴이 발생하게 된다. 플랜지나 복부의 폭-두 께비가 큰 경우 횡-비틀림좌굴 발생 이전에 국부좌굴이 발생하며, 국부좌굴은 휨부재의 횡-비틀림좌굴강도에 영향을 미치게 된다. 이런 현상은 박판 형강의 휨강도 산정 시 고려하여야 한다. 다양한 폭-두께비를 갖는 플랜지와 복부판으로 구성된 휨부재의 해석에 국부좌굴 및 횡좌굴 모드의 초기처짐 및 잔류응력을 포함하였다. 해석결과 및 실험에 근거하여 국부좌굴과 횡-비틀림좌굴을 고려하는 설계강도식을 제안하였다. 제안된 직접강도법은 실험에 근거한 강도식과 유효단면 대신 총단면의 단면계수를 사용한다. 제안된 강도식에 의한 휨강도를 AISC, EC3 및 도로교설계기준과 비교하여 보았다. 제안된 직접강도법은 국부좌굴과 횡-비틀림좌굴의 혼합 유무와 상관없이 휨부재의 휨강도를 적절하게 예측할 수 있는 것으로 판단되었다.

양계장 살모넬라 감염 제어를 위한 친환경 신기술 동향과 응용

서건호 한국가금학회 2008 한국가금학회 심포지움 Vol.- No.-

제형 및 사인형 주름 강판의 초기 불완전 형상을 고려한 전단 좌굴 특성 비교

서건호,손수덕,이승재,Seo, Geonho,Shon, Sudeok,Lee, Seungjae 한국공간구조학회 2021 한국공간구조학회지 Vol.21 No.4

This paper conducted a comparative analysis of the shear buckling characteristics of trapezoidal and sinusoidal corrugated steel plates considering of their initial imperfection. Initial imperfection refers to the state where the shape of the corrugated plate is initially not perfect. As such, an initially imperfect shape was assumed using the eigen buckling mode. To calculate the buckling stress of corrugated steel plates, the linear buckling analysis used a boundary condition which was applied to the plate buckling analysis. For the comparison of trapezoidal and sinusoidal corrugation, the shape parameters were assumed using the case where the length and slope of each corrugation were the same, and the initial imperfection was considered to be from 0.1% to 5% based on the length of the steel plate. Here, for the buckling analysis, ANSYS, a commercial FEA program, was used. From the results of buckling analysis, the effect of overall initial imperfection showed that the larger the initial imperfection, the lower the buckling stress. However, in the very thin model, interaction or local buckling was dominant in the perfect shape, and in this case, the buckling stress did not decrease. Besides, the sinusoidal model showed higher buckling stress than the trapezoidal one, and the two corrugation shapes decreased in a similar way.

2002 년도 제 27 회 보건학종합학술대회 : 미생물 노출모델을 이용한 미생물 성장 예측과 식품 위해도 관리

서건호(Kun Ho Seo) 대한보건협회 2002 대한보건협회 보건종합학술대회 Vol.- No.-

기후변화에 따른 식품매개질환의 영향 예측 및 관리 대책

서건호(Kun-Ho Seo) 대한수의학회 2010 대한수의학회 학술대회발표집 Vol.2010 No.-

식품 위험분석과 미생물 위해평가의 알기쉬운 이해

서건호 ( Kun Ho Seo ) 한국식품위생안전성학회 2009 Safe Food Vol.4 No.4

Gold Nanoparticle and Polymerase Chain Reaction (PCR)-Based Colorimetric Assay for the Identification of Campylobacter spp. in Chicken Carcass

홍승환,서건호,윤성호,김수기,천정환 한국축산식품학회 2023 한국축산식품학회지 Vol.43 No.1

Campylobacteriosis is a common cause of gastrointestinal disease. In this study, we suggest a general strategy of applying gold nanoparticles (AuNPs) in colorimetric biosensors to detect Campylobacter in chicken carcass. Polymerase chain reaction (PCR) was utilized for the amplification of the target genes, and the thiolated PCR products were collected. Following the blending of colloid AuNPs with PCR products, the thiol bound to the surface of AuNPs, forming AuNP-PCR products. The PCR products had a sufficient negative charge, which enabled AuNPs to maintain a dispersed formation under electrostatic repulsion. This platform presented a color change as AuNPs aggregate. It did not need additional time and optimization of pH for PCR amplicons to adhere to the AuNPs. The specificity of AuNPs of modified primer pairs for mapA from Campylobacter jejuni and ceuE from Campylobacter coli was activated perfectly (C. jejuni, p-value: 0.0085; C. coli, p-value: 0.0239) when compared to Salmonella Enteritidis and Escherichia coli as non-Campylobacter species. Likewise, C. jejuni was successfully detected from artificially contaminated chicken carcass samples. According to the sensitivity test, at least 15 ng/μL of Campylobacter PCR products or 1×103 CFU/mL of cells in the broth was needed for the detection using the optical method.

Sensory Qualities of Non-Dairy and Dairy Products Fortified with Aloe Oil: A Preliminary Study

김태진,서건호,천정환,윤혜영,김현진,김영선,김빈,허제강,정동관,송광영 한국낙농식품응용생물학회 2022 Journal of Dairy Science and Biotechnology (JMSB) Vol.40 No.2

Aloe vera has several beneficial health effects as it interacts with probiotics and is also a source of prebiotics, antioxidants, and other bioactive materials. Thus, there has been increasing interest in the development of beverages containing Aloe vera. In this investigation, sensory qualities were estimated by fortifying oil isolated from Aloe vera in non-dairy and dairy products at different concentrations (fortified with 1% increments from 0% to 5%). Because of the strong aroma and strong yellow color of aloe oil, the sensory quality values estimated in this study were generally low. However, the samples fortified with 1% aloe oil exhibited the best sensory quality values compared with the control. Consequently, the results of this study are valuable as preliminary findings to determine the various sensory qualities of kefir fortified with aloe oil. To improve sensory qualities in the future, it is necessary to estimate the optimal lowering of the concentration of fortified aloe oil, and assess whether aloe oil exhibits various biofunctional activities at different concentrations

Isolation and Characterization of Halophilic Kocuria salsicia Strains from Cheese Brine

윤혜영,서건호 한국축산식품학회 2022 한국축산식품학회지 Vol.42 No.2

Kocuria salsicia can survive in extreme environments and cause infections, including catheter-related bacteremia, in humans. Here, we investigated and evaluated the characteristics of nine K. salsicia strains (KS1–KS9) isolated from cheese brine from a farmstead cheese-manufacturing plant in Korea from June to December, 2020. Staphylococcus aureus American Type Culture Collection (ATCC) 29213 was used as a positive control in the growth curve analysis and biofilm-formation assays. All K. salsicia isolates showed growth at 15% salt concentration and temperatures of 15℃, 25℃, 30℃, 37℃, and 42℃. KS6 and KS8 showed growth at 5℃, suggesting that they are potential psychrotrophs. In the biofilm-formation analysis via crystal violet staining, KS6 exhibited the highest biofilm-forming ability at various temperatures and media [phosphate buffered saline, nutrient broth (NB), and NB containing 15% sodium chloride]. At 25℃ and 30℃, KS3, KS6, and KS8 showed higher biofilm-forming ability than S. aureus ATCC 29213. The antimicrobial resistance of the isolates was evaluated using the VITEK® 2 system; most isolates were resistant to marbofloxacin and nitrofurantoin (both 9/9, 100%), followed by enrofloxacin (7/9, 77.8%). Five of the nine isolates (5/9, 55.6%) showed multidrug resistance. Our study reports the abilities of K. salsicia to grow in the presence of high salt concentrations and at relatively low temperatures, along with its multidrug resistance and tendency to form biofilms.

Organoleptic Quality Assessment of Dairy and Nondairy Products Supplemented with Ginger Oil: A Preliminary Study

김태진,서건호,천정환,윤혜영,정동관,송광영 한국낙농식품응용생물학회 2022 Journal of Dairy Science and Biotechnology (JMSB) Vol.40 No.3

The root of ginger (Zingiber officinale) contains gingerol, which is known to be responsible for its pharmacological activity. The essential oil extracted from ginger has been found to have various pharmacological effects. Thus, interest in the development of various beverages using ginger oil has recently increased. Therefore, in this study, the organoleptic quality assessment of cow milk, yogurt, kefir, soy milk, oat milk, and almond milk was conducted by supplementing them with oil extracted from ginger at various concentrations (supple- mented with 0.5% increments from 0% up to 2%). A poor grade was obtained in the organoleptic quality evaluation, owing to the strong odor of ginger oil. However, when compared to that of the control, the samples supplemented with 0.5% ginger oil showed a good grade of organoleptic quality assessment. Therefore, this study is considered valuable as it is the first study to review the organoleptic quality assessment by supplementing milk, yogurt, kefir, soy milk, oat milk, and almond milk with ginger oil. Additionally, in order to improve organoleptic quality assessment, it is critical to estimate how much ginger oil supplementation concentration could be reduced and whether ginger oil exhibits various bio-activities at this concentration.