• 한국구조물진단유지관리공학회 논문집
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• 제24권6호
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• pp.25-33
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• 2020

취성재료의 변형률 분포와 인장물성과의 상관관계를 분석하기 위해 변형률 분포를 가지도록 탭부분을 변형한 5개 타입-S0, SD1, SD2, SV1, SV2 - 의 탄소섬유보강폴리머(CFRP) 인장시편군을 시험하였다. 변형률 분포가 큰 SD2, SV2 의 극한응력 및 변형률이 SD1, SV1 보다 작게 나타났는데, 이는 비대칭 형상의 SD타입보다 대칭 형상의 SV의 시험결과에서 더 분명하게 나타냈다. 더불어 본 연구에서 사용한 변형률 분포를 가진 대부분의 시편의 극한 응력 및 변형률은 변형률 분포가 없는 대조군과 비교하였을 때 감소하였다. 이러한 결과는 1) 변형률계를 통해 직접 계측한 변형률의 평균값, 2) 전체변형량을 유효길이로 나눠 산정하는 환산변형률, 3) 탄성계수와 극한하중으로부터 유도하는 (극한)유효변형률을 통해 다각적으로 분석되었다. 변형률계에서 계측된 값은 국소구간 응답을 정확히 나타내지만, 전단면의 응답을 표현하는 것은 아니다. 반면, 환산변형률과 유효변형률은 전단면의 평균거동을 나타내므로, 게이지의 단점을 보완할 수 있다. 특히 유효변형률은 극한하중 부근에서 변형률계 측정값이 게이지 손상이나 비정상적 계측값 등의 원인으로 유효하지 않을 때도 실무적으로도 사용할 있는 보수적인 파단변형률을 산정할 수 있다. 이 값은 부분파단이 발생한 경우에도 사용할 수 있으며, 변형률 분포를 가지는 시편에서 합리적으로 유용하다.

• 한국식품영양과학회지
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• 제42권5호
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• pp.663-669
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• 2013

인삼과 마찬가지로 많은 사포닌을 함유하고 있는 인삼꽃의 이용 가치를 증진시키기 위한 연구의 일환으로 Bacillus subtilis(BS), Lactobacillus plantarum(LP), Lactobacillus casei(LC), Candida utilis(CU), Saccharomyces cerevisiae strain CHY1011(Y1), Saccharomyces cerevisiae strain ZP 541(Y2), 혼합발효(M) 등의 여러 유용 미생물을 이용하여 인삼꽃을 발효시킨 후 미생물별 인삼꽃 발효물에 대한 항산화 활성 변화를 탐색하였다. 총 페놀함량 측정 결과 무발효 추출물은 인삼꽃 발효물에 비해 유의적(p<0.05)으로 높은 값을 보였으며, 발효 균주 중에서는 BS로 발효한 발효물이 가장 높은 값을 나타내었다. DPPH radical 소거활성 및 ABTS radical 소거활성 측정 결과 BS 발효물이 유의적으로 가장 높은 활성을 나타내었으나, FRAP value(10 mg/mL)는 무발효 추출물의 활성이 가장 높게 나왔으며 BS 발효물과는 유의차를 보이지 않았다. 환원력 측정 결과, 대체적으로 무발효 추출물에 비해 미생물 발효물에서 높은 활성을 나타내었으며 LC 발효물이 높은 활성을 나타내었다. 따라서 여러 유용미생물을 이용한 인삼꽃 발효의 경우 Bacillus subtilis를 이용하여 발효할 경우 다른 균주들을 이용하는 것보다 항산화 활성 증진에 우수한 효과를 나타낼 것으로 사료되며 다른 생리활성 증진 효과에 대한 연구가 좀 더 진행되어져야 할 것이다.

• 한국산림과학회지
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• 제87권3호
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• pp.429-444
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• 1998

Picea mariana 생장을 억제하는 Kalmia angustifolia에 영향을 주는 외생근균을 조사 선발하였다. 11개 외생근균중에서 19계통을 선발하여 Kalmia 잎침출물이 들어있는 배지에 P. mariana 치묘와 함께 근균을 접종하여 자라는 형태와 생장양상을 조사하였다. Kalmia 잎추출물을 첨가한 액체배지에서는 균사의 건중량을, 한천배지에서는 코로니의 직경을 측정한 결과 분리된 9개 균주에서는 현저하게 억제되었으나 나머지 10개 균주에서는 반대로 증가되거나 Kalmia의 영향이 나타나지 않았다. 배양배지의 pH가 3-4일 때는 생장을 억제 받는 근균도 있었으나 pH와 잎침출물을 조합한 조건하에서는 더욱 강하게 억제되었다. 분리된 13개 계통은 순수배양에서 Kalmia 잎침출물 25%와 함께 배양한 P. mariana에서 외생근균이 형성되었다. Paxillus involutus(NF4), Cenococcum geophilum(GB12), Laccaria laccata(GB23), E-strain(GB45)계통에서는 Kalmia 잎추출물 50%에서 배양한 결과 다른 계통보다 많은 외생근균이 형성이 되었다. 이러한 근균을 미리 접종한 P. mariana를 Kalmia 잎추출물과 같이 배양한 후 온실 안에서 4개월동안 Kalmia와 갈이 재배하였다. P. involutus, L. laccata 와 E-strain 미리 접종한 치묘에서는 많은 근균(흡수근외 77-91%)이 형성되었으나 C. geophilum를 미리 접종한 치묘에서는 근균이 비교적(흡수근의 32%) 적게 형성되었다. 외생균근이 대부분의 치묘에서 생겼음에도 불구하고 근균의 90% 이상이 접종근균에서 생겨났다. 근균의 지속적인 생장은 살아있는 Kalmia 식물개체에 영향을 받지 않았다. P. involutus, L.laccata와 E-strain과 같이 처리한 치묘 근균의 80% 이상과 C. geophilum을 처리한 치묘 근균의 53%가 접종된 균주의 영향을 받았다. 대조구에서는 토착균주에 의해 약 45%의 짧은 뿌리의 외생근균이 형성되었다. L. laccata와 C. geophidum는 Kalmia잎추출물과 같이 배양한 치묘의 근균행성을 촉진하였다. 균주를 접종한 경우 근균형성율은 pH5보다 pH4에서 4-15% 더 낮았으며 L. laccata를 접종한 경우 심하게 억제되었다. P. involtus에 접종한 치묘는 L. laccata를 E-strain를 접종한 치묘보다 줄기와 뿌리생장이 가장 높게 나타났다. P. involtus와 L. laccata를 접종한 치묘는 대조구의 치묘보다는 건중량이 많고 키가 훨씬 컸다. E-strain에 접종한 치묘는 대조구와 비교해서 1차 측근 수가 매우 작았으며 줄기 건중량은 매우 높게 나타났으나 다른 형질, 예를 들면 흡수근, 뿌리 건중량, 수고 등은 대조구와 크게 다르지 않았으나 C. geophilum에 접종한 치묘는 1차 측근수를 제외한 다른 생장 특징에서는 대조구와 크게 다르지 않았다.

• International Journal of Industrial Entomology and Biomaterials
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• 제33권1호
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• pp.15-23
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• 2016

One major constraint in the development and implementation of a successful and cost-effective area-wide integrated pest management (AW-IPM) programme with a SIT component for Bactrocera oleae (Diptera: Tephritidae) is the ability to produce a large number of high quality mass-reared individuals. The aim of this study was to develop a more efficient and practical egg collection system in an attempt to improve the mass-rearing of this species. The following basic parameters were examined: egg production per female, egg hatch, pupal recovery, pupal weight, adult emergence and percentage of fliers. Three different strains (Israel wild-type, France wild-type, and Greece laboratory) were tested and each strain was evaluated for six generations. Female flies of the Israel strain produced significantly more eggs per female than the other two strains, but egg hatch was significantly lower. Egg hatch of the France wild type and the Greece laboratory strain was similar. For all other parameters, there was no significant difference between strains; however, there was a significant generational effect for all parameters observed. As a result of this study, a protocol was developed for the mass-rearing of this species that included the use of large adult holding cages that could house up to 96,000 flies per cage. The newly developed method of egg collection using a flat wax panel as one of the sides of an adult holding cage proved to be cost-effective, efficient, making colony growth easier for industrial mass-rearing.

• Journal of Preventive Medicine and Public Health
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• 제32권4호
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• pp.505-512
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• 1999

Objectives : The purpose of this study was to assess the relationship between job strains and absenteeism from work. Methods : The study design was cross-sectional, and the study subjects consisted of 1,166 workers who were employed in the small-sized industries. A self administered questionnaire was used to measure the general characteristics, job characteristics(job demand, job control), and social support(coworker support, supervisor support) at work. The Job Content Questionnaire(JCQ) was used to assess job demand(2 items) and decision lattitude(10 items). Social support at work (10 items) was measured using JCQ. Sick absence was collected using self-report and were rechecked by the attendance record of their company. Odds ratios and 95% confidence intervals for the association between job strain and sick absence were estimated. The modifying effect of social support was evaluated by stratification. Logistic regression was used to estimate the relationship between job strain and sick absence. Results : In the bivariate analysis, the variables related to sick absence were age, marital status, occupation, job demand. Four distinctly different kinds of level of job strain were generated by the combination of job demand and job control: low strain group, high strain group, active group, and passive group. The crude odds ratio of high job strain was 1.78(95% CI: 1.26-2.53), and those of active group and passive group were 1.33(95% CI: 1.07-1.66) and 1.13 (95% CI: 0.88-1.47), respectively. The odds ratio of high job strain after adjusting for age and occupation were still significant The odds ratio of high job strain in low social support was 5.96(95% CI: 2.45-14.51), but that in high social support was 0.73(95% CI: 0.26-2.01). Conclusions : Job strain was associated with increased risk of absenteeism from work, and social support at work modified the association between job strain and sick absence.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.609-615
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• 2005

The safety and immunogenicity of an attenuated recombinant Salmonella vaccine strain, Salmonella enterica serovar Typhimurium llaB, was assessed. This vaccine strain could survive in low pH condition, and its ability of intracellular survival did not differ from that of S. enterica serovar Typhimurium UK1, which is the wild-type of the vaccine strain. The mortality of the mice orally administered with the vaccine strain was $50\%$ at the dose of $10^7$ CFU. All mice administered with $10^5\;or\;10^3$ CFU of the vaccine strain survived for 3 days postinoculation (pi). However, all mice administered with more than $10^3$ CFU of the vaccine strain died within 3 days pi. To examine the protective effect of the vaccine strain, mice were orally immunized with $10^4\;and\;10^6$ CFU of the bacteria. Control mice were given with 0.5 ml of phosphate buffered saline (PBS). After 8 days, the mice were challenged with $10^9$ CFU of S. enterica serovar Typhimurium UK1, and mortality was examined for 5 days. The survival rates of the mice immunized with $10^4\;and\;10^6$ CFU of the vaccine strain were $60\%\;and\;80\%$, respectively, whereas all control mice died within 2 days after challenging. To investigate the immunogenicity of S. enterica serovar Typhimurium llaB, mice were orally immunized with $10^5\;or\;10^6$ CFU ml of the vaccine strain. Five mice of each group were sacrificed at 5 and 12 days after immunization, and results showed that immunization of the vaccine strain led to increases of IgG1, IgG2, and IgM titers against S. enterica serovar Typhimurium UK1 in mouse sera, cytokine expressions such as IL-2, IL-4, IL-6, and IL-10 in spleen, and the lymphocyte proliferation response to mitogens (concanavalin A or LPS) stimulation.

• Steel and Composite Structures
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• 제18권1호
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• pp.29-50
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• 2015

With a quasi-three point bending apparatus, ratcheting deformation is studied experimentally on a pressurized austenitic stainless steel Z2CND18.12N pipe under bending load and vertical displacement control, respectively. The characteristic of ratcheting behavior of straight pipe under both control methods is achieved and compared. The cyclic bending loading and internal pressure influence ratcheting behavior of pressurized straight pipe significantly under loading control and the ratcheting characteristics are also highly associated with the cyclic displacement and internal pressure under displacement control. They all affect not only the saturation of the ratcheting strain but the ratcheting strain rate. In addition, ratcheting simulation is performed by elastic-plastic finite element analysis with ANSYS in which the bilinear model, Chaboche model, Ohno-Wang model and modified Ohno-Wang model are applied. By comparison with the experimental data, it is found that the CJK model gives reasonable simulation. Ratcheting boundaries under two control modes are almost same.

• 농업과학연구
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• 제44권4호
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• pp.558-565
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• 2017

This study was conducted to determine the effect of inoculation of microorganism isolated from pig feces on nutrient contents of fermented hulless barley. The microbial flora in feces of a total of four crossbred piglets ($Landrace{\times}Yorkshire{\times}Duroc$) was analyzed by 16s rRNA sequencing. The most abundant strain was then selected for fermentation of hulless barley. Lactobacillus plantarum (L. plantarum) was dominant (64.56%) in intestinal microbial flora in the pig feces. The selected candidate strain showed significantly higher survival rate at pH 7 than at pH 2.5 and 3.0 (p < 0.05). Incubated culture containing the candidate strain showed an increased growth rate with lower pH levels after 7.5 h incubation compared to initial incubation period (p < 0.05). When compared with commercial multiple probiotics which were used as control, the selected strain showed faster growth rate at 5 h post-incubation (p < 0.05). During the fermentation period, neither inoculated nor non-inoculated control hulless barley showed any change in pH value. Crude fat, fiber and ash contents were lower (p < 0.05) in hulless barley inoculated by the selected strain compared to control. However, moisture, energy, NDF and ADF were not affected by the inoculation of strain or fermentation period. Lactic acid was increased and acetic acid was decreased in the hulless barley inoculated with the selected strain during the fermentation period (p < 0.05). Taken together, our results suggest that L. plantarum derived from the pigs could be utilized as a new microorganism for manufacturing fermented feed stuffs.

• 한국터널지하공간학회 논문집
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• 제13권6호
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• pp.501-517
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• 2011

일반적으로 터널 시공현장에서는 계측된 천단 및 내공변위와 계측관리기준을 비교하여 터널의 안정성을 판단한다. 현재 계측관리기준은 지반조건, 터널단면의 크기, 시공방법, 지보재량 등을 고려한 경험을 통해 세워지고 있는 실정이다. 따라서 새로운 계측관리기준으로 한계변형률을 이용하는 방법에 대한 연구가 다수 수행되었다. 그러나 대부분의 연구는 일축압축강도실험에서 얻어진 한계변형률을 기준으로 삼고 있어 실제 터널 굴착 시 발생하는 응력의 증가 및 종방향 아칭에 의한 암반 손상을 고려하지 않는 문제점을 가지고 있다. 따라서 본 연구에서는 국내 대표 암종인 화강암과 편마암의 한계변형률 특성을 조사하기 위하여 일축압축강도실험과 응력의 증가 및 종방향 아칭을 고려한 손상제어실험을 수행하였다. 손상제어실험에서 얻어진 한계변형률은 일축압축강도실험에서 얻어진 한계변형률보다 다소 작게 나타났다. 이는 일축압축강도실험에서 얻은 한계변형률은 터널 굴착 시의 응력이력을 고려하여 다소 감소시켜야 한다는 것을 의미한다. 또한 대심도 터널에서 흔히 발생하는 취성파괴를 평가하기 위한 손상한계변형률을 제안하였다.

• The Journal of Advanced Prosthodontics
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• 제8권2호
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• pp.116-124
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• 2016

PURPOSE. The aim of the present study was to evaluate, by means of strain gauge analysis, the effect of different implant angulations on strains around two implants retaining mandibular overdenture with Locator attachments. MATERIALS AND METHODS. Four duplicate mandibular acrylic models were constructed. Two implants were inserted in the canine regions using the following degrees of distal inclinations: group I (control); $0^{\circ}$, group II; $10^{\circ}$, group III; $20^{\circ}$, and group IV; $30^{\circ}$. Locator pink attachments were used to connect the overdenture to the implants and Locator red (designed for severely angled implants) was used for group IV (group $IV_{red}$). For each group, two linear strain gauges were attached at the mesial and distal surfaces of the acrylic resin around each implant. Peri-implant strain was measured on loading and non-loading sides during bilateral and unilateral loading. RESULTS. For all groups, the mesial surfaces of the implants at loading and non-loading sides experienced compressive (negative) strains, while the distal implant surfaces showed tensile (positive) strains. Group IV showed the highest strain, followed by group III, group II. Both group I and group $IV_{red}$ showed the lowest strain. The strain gauges at the mesial surface of the loading side recorded the highest strain, and the distal surface at non-loading side showed the lowest strain. Unilateral loading recorded significantly higher strain than bilateral loading. CONCLUSION. Peri-implant strains around two implants used to retain mandibular overdentures with Locator attachments increase as distal implant inclination increases, except when red nylon inserts were used.