• 한국세라믹학회지
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• 제34권10호
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• pp.1053-1059
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• 1997

The dynamic fatigue behavior of alumina ceramics was observed at room temperature using four point bending system. The dynamic fatigue fracture strength and the dynamic fatigue lifetime were observed as a function of crosshead speed and the notch length. The notched specimen showed the smaller deviation in dynamic fatigue fracture strength than the unnotched specimen. The crack growth exponent n and the material constant A of the notched specimen could be represented as functions of the notch length. Fracture strength of the specimen calculated from the notch length, when the notch length was regarded as the crack size, was in good agreement with the measured 4 point bending strength. Fracture surface of the specimen showed the different fracture modes according to the crosshead speed. The four point flexural strength, fracture toughness, Young's modulus and Weibull modulus of the alumina were measured as 360 MPa, 3.91 MPa.m1/2, 159GPa, 17.64, respectively.

• Mycobiology
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• 제49권3호
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• pp.280-284
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• 2021

Mushroom strains of Polyporales from the genera Coriolus, Trametes, Pycnoporus, Ganoderma, and Formitella were explored in terms of mycelial growth characteristics for the application of mushroom mycelia as alternative sources of materials replacing fossil fuel-based materials. Among the 64 strains of Polyporales, G. lucidum LBS5496GL was selected as the best candidate because it showed fast mycelial growth with high mycelial strength in both the sawdust-based solid medium and the potato dextrose liquid plate medium. Some of the Polyporales in this study have shown good mycelial growth, however, they mostly formed mycelial mat of weak physical strength. The higher physical strength of mycelial mat by G. lucidum LBS5496GL was attributed to its thick hyphae with the diameter of 13 mm as revealed by scanning electron microscopic analysis whereas the hyphae of others exhibited less than 2 mm. Glycerol and skim milk supported the best mycelial growth of LBS5496GL as a carbon and a nitrogen source, respectively.

• Journal of Plant Biotechnology
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• 제34권3호
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• pp.263-269
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• 2007

식물 세포나 조직의 배양에서 배지의 salt strength, sucrose 농도, 질소 함량과 질소원의 종류 및 그 비율 등이 세포 또는 조직의 생장에 영향을 미친다. 본 연구에서는 Agar를 함유한 MS 기본배지와 BA 1 mg/L를 첨가한 MS 기본 액체배지에서 계대배양을 통하여 생산한 다신초를 액아와 본엽이 $2{\sim}3$매 되도록 분할한 신초를 이용하여 MS 액체배지의 salt strength와 sucrose 농도 및 $NH_4/NO_3$ 비율이 고추냉이 신초의 생육에 미치는 영향을 조사하여 고추냉이 유묘의 생산에 필요한 최적 배지조건을 구명하였다. 고추냉이 신초의 증식에는 MS 액체배지의 salt strength는 기본조성이 가장 적합한 것으로 나타났으며, $1/4{\sim}1/2x$ 또는 2x MS 배지에서는 고추냉이 유묘의 생장이 크게 억제 되었다. 기본조성의 MS 액체배지에 sucrose 3%를 첨가하였을 때 고추냉이 신초의 생장이 가장 우수한 것으로 나타났으나 sucrose 농도 $1{\sim}6%$ 범위에서 신초의 수와 길이는 유의성 있는 차이를 보이지 않았다. 기본조성의 MS 액체배지에서 질소원으로 ${NH_4}^+$과 ${NO_3}^-$의 비율을 10:50으로 조절하였을 때 고추냉이 신초의 생장이 가장 우수한 것으로 나타났으며, ${NH_4}^+$의 비율이 증가할수록 생장은 억제되었다.

• Annals of Rehabilitation Medicine
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• 제42권6호
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• pp.822-832
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• 2018

Objective To determine the socio-demographic, psychologic, hematologic, or other relevant factors associated with hand grip strength in Korean farmers. Methods A total of 528 healthy Korean farmers were enrolled. Hand grip strength was measured in both hands using a hydraulic dynamometer. Socio-demographic characteristics were assessed and anthropometric measurements were obtained. Psycho-cognitive measurements such as sleep quality (Pittsburgh Sleep Quality Index) and Go/No-Go test response time were conducted. In addition to physical measurements, serologic parameters including insulin-like growth factor 1 were measured. The factors associated with hand grip strength were analyzed using multiple linear regression analysis after adjusting for age, height, and weight. Results The mean hand grip strength was associated with the Pittsburgh Sleep Quality Index total score (${\beta}=-0.12$, p=0.01), the Go/No-Go test response time (${\beta}=-0.18$, p=0.001), vitamin D (${\beta}=0.12$, p=0.02), and insulin-like growth factor 1 levels (${\beta}=0.1$, p=0.045). In female farmers, hand grip strength was only associated with the Pittsburgh Sleep Quality Index total score (${\beta}=-0.32$, p<0.001). Conclusion The results of this study demonstrate that hand grip strength was associated with sleep quality and attention in Korean farmers.

• 생물환경조절학회지
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• 제19권4호
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• pp.210-216
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• 2010

양액농도에 따른 여러 관엽식물의 생육반응을 구명하여 양분관리의 기준을 설정하고 초기 생육을 촉진시키고자 본 실험을 수행하였다. 실험재료로 벤자민고무나무, 관음죽, 필로덴드론, 스파티필럼, 아이비 등 많이 이용되고 있는 관엽식물들을 속별로 선택하였다. 화분에 식재한 관엽식물에 0, 1/4, 1/2, 1배액의 Sonneveld 분화전용양액을 저변관수하였으며, 28주 후 식물의 초장, 폭, 엽수, 엽면적, 생체중 및 건물중 등을 측정하였다. 그 결과, 관엽식물은 종류에 따라 영양요구도가 다름을 알 수 있었다. 벤자민고무나무와 필로덴드론은 양액농도가 높아질수록 식물의 생육이 증진되었으나, 아이비와 스파티필럼은 1/4과 1/2배액에서 생육이 가장 좋았다. 관음죽의 경우 l배액에서만 생육이 약간 증진되었고 1/4과 1/2배액에서는 무처리구와 거의 차이가 없었다. 관엽식물의 엽내 무기이온을 정량한 결과 중 N, P, K 등이 생육에 가장 크게 영향을 준 것으로 판단되었다. 관엽식물에 대한 관수와 시비의 기준들이 명확히 제시되지 않고 있고, 재배시 초기생육이 느리다는 단점이 있어 이 기간을 단축시킬 필요성이 있다. 본 실험에서는 이런 점들을 보완하려고 하였고, 양액에 의해 식물의 생육도 증진됨을 알 수가 있었다. 적합한 양액농도로 관리해주면 생육이 빨라지고 품질도 우수해졌다.

• 산업기술연구
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• 제21권A호
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• pp.329-336
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• 2001

In this study, a series of fatigue tests are carried out in order to estimate quantitatively the characteristics of fatigue crack growth rate for high strength steels of SM570, POSTEN60, and POSTEN80 steel, that is, the influence on fatigue crack growth rate according to the welding line, the characteristics of fatigue crack growth according to the welding method and the kinds of steel, and the characteristics of fatigue crack growth for base metal, heat affected zone and weld metal. From the test results, in case that the notch if parallel to welding line, it knows that the retardations of fatigue crack growth rate in crack tip at early stage increase remarkably than in case that the notch is perpendicular to welding line due to compressive residual stress. And the characteristics of fatigue crack growth rate according to welding method are that the dispersion of fatigue crack growth rate in case of FCAW method is smaller than that of SAW method. Also, it knows that the fatigue crack growth rate converges in high stress intensity factor range.

• 한국자원식물학회지
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• 제16권3호
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• pp.223-229
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• 2003

본 연구는 양액재배 오이의 생장과 수량에 나쁜 영향을 주지 않는 적정 양액 농도를 구명하기 위해서 양액의 이온 농도를 달리하였다. Yamazaki의 오이 처방을 기본으로 하여 1/4, 1/2, 3/4, 1, 3/2, 2 배농도를 상이하게 처리하여 생장 특성, 수량 및 질소 함량을 비교하고자 수행하였고 그 결과를 요약하면 다음과 같다. 1. 생육 시기별 초장과 엽수의 증가속도는 저 농도 구인 1/2배 농도에서 가장 빠른 증가속도를 보였다. 2. 양액의 이온농도 차이에 따른 오이의 생육 형질은 유의적인 생장의 차이가 인정되지 않았으며, 생육 시기별 초장, 경장과 엽면적은 1/2배 농도구에서 수치상으로 가장 높은 값을 보였다. 3. 양액의 이온농도 차이에 따른 오이의 과실수량은 유의적인 차이가 인정되지 않았으며 주수에서는 고농도구인 2배 농도가 86.00, 86.75로 가장 높은 값을 보였고, 과실수는 1/4배 농도와 표준 농도에서 가장 낮은 74.25, 85.25를 보였으나 수량에서는 저 농도인 1/2배 농도와 3/4배 농도가 가장 높은 22.60, 22.07kg을 보였다. 4. 질소함량은 유의적인 차이가 인정되지 않았으며, l/2배 농도에서 대체적으로 높은 함량을 보였다. 5. 양액의 이온농도 차이에 따라 정식후 36일 조사 시기의 모든 생육형질과 수량 특성에서 수치상으로 높은 값을 보인 1/2배 농도에서의 상관관계는 초장과 경장은 고도로 유의한 정의 상관관계를, 초장과 엽면적에서는 유의한 정의 상관관계를 나타냈고, 주수와 과실수는 고도로 유의한 정의 상관관계를, 과실수와 수량은 유의한 정 의 상관을 나타냈다.

• 한국학교보건학회지
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• 제5권1호
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• pp.111-119
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• 1992

The study examined the difference of the physique, the physical strength, and the physical constitution between meal and non-meal service schools at the countryside, and concluded as follows: 1) The effects on the physical development Meal service school student's height was 0.41~2.38cm taller, weight 0.21~1.58kg heavier, and the chests 0.15~2.55cm bigger than the non-meal service school students. Therefore, the effects of the school meal service on the student's physique development proved positive. 2) The effects on the physical strength Today, the student's physical growth is reinforced by consuming high calorie food, while their physical exercise is decreased. As a result, obesity becomes another problem. In this respect, physical strength is a significant factor in judging the physical condition of the students. This study compared the meal service schools with the non-meal service schools by suing six items of the physical strength test those schools. In comparison, the meal service school students were better than the others in most items except in the eleven year old girl's 100 meter running and the ball throwing, and the ten year old boy's 600meter running. It means that school meal service affects the physical growth in a positive manner. 3) The effects on the physical constitution The students in their growing period should have their meals not only balanced, but regularly since this helps to maintain their health. Insufficient nutrition may disturb the balanced physical growth of cause a weak or powerless physical constitution. As shown at the table 6, meal service school students who had a balanced meal have 0.01% lower incidence of disease. and 3.11~7.32% less myophia than the other. The average 0.39 to 0.63 cavity of the meal service school students also show that their constitutions are better than the non-meal service ones. In conclusion, the school meal service program gives every student a regular nutritious meal which results in a balanced physical growth. Erentually, the healthier students could be the healthier social menbers which promise a brighter society in the future.

• Archives of Plastic Surgery
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• 제32권4호
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• pp.516-520
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• 2005

Multilayered cartilage graft has been clinically used at tip plasty, total ear reconstruction, and cleft lip nasal deformities. Perichondrial flap or a free perichondrium has been also commonly used for induction of neocartilage. However, the influence of perichondrium on multilayered cartilage graft to strength and growth rate is still unknown. The purpose of this study was to compare the strength and growth rate of different multilayered cartilage graft and to present the most ideal model of multilayered cartilage graft. Twenty New-zealand white rabbit were used. Triple layers of cartilage grafts with various perichondrium were inserted into six separate pockets in paravertebral region of rabbits. The grafts were grossly and microscopically observed on 8 and 16 weeks after grafting. On gross observation, the grafts showed marked enlargement of three layers of cartilage grafts with perichondrium compare with three layers of cartilage grafts without perichondrium In histologic examination, the number of PCNA-labelled cells were significantly high on three layers of cartilage grafts with perichondrium. In conclusion, this study suggested that triple-layer graft of cartilage grafts with perichondrium on the outside of triple-layer graft has strength and an effect on chondrogenetic induction by the perichondrium.

• 한국의류학회지
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• 제2권2호
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• pp.237-243
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• 1978

Dermatophytes such as Trichophyton mentagrophytes, Trichophyton rubrum and Epidermophyton floccosum are used in this study to confirm (a) The Dermatophytes could utilize the wool, cotton and nylon fiber as a nutrient source. (b) The degree of damage of fibers by the Dermatophytes growth. The results of the experiment are summarized as follows; 1. Dermatophytes could not utilize the wool, cotton and nylon fiber directly as a nutrient source without the exogenously applied nutrients. 2. It was presumed that Dermatophytes could utilize the knitted wool fabric as their nutrient source when nutrient was exogenously applied. since the knitted wool fabric was greatly damaged by T. mentagrophytes and T. rubrum growth. 3. The tensile strength of knitted wool fabric was significantly decreased by T. mentagrophytes and T. rubrum, but not by E. floccosum. However, the tensile strength of knitted nylon fabric was not particularly affected by the Dermatophytes. 4. The burst strength of knitted wool fabric was decreased by T. mentagrophytes ($77\%$). T. rubrum ($53\%$). and E. floccosum ($15\%$). Though the burst strength of knitted cotton fabric was decreased by Dermatophytes about $20\%$, that of knitted nylon fabric was not affected. 5. Observing the damaged wool fiber by scanning microscope, the inner part of wool fiber was permeated by T. mentagrophytes and T. rubrum.