• Smart Structures and Systems
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• 제30권1호
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• pp.63-74
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• 2022

The deformation coordination between a rock/soil mass and an optical sensing cable is an important issue for accurate deformation monitoring. A stress-controlled triaxial apparatus was retrofitted by introducing an optical fiber into the soil specimen. High spatial resolution optical frequency domain reflectometry (OFDR) was used for monitoring the strain distribution along the axial direction of the specimen. The results were compared with those measured by a displacement meter. The strain measured by the optical sensing cable has a good linear relationship with the strain calculated by the displacement meter for different confining pressures, which indicates that distributed optical fiber sensing technology is feasible for soil deformation monitoring. The performance of deformation coordination between the sensing cable and the soil during unloading is higher than that during loading based on the strain transfer coefficients. Three hypothetical strain distributions of the triaxial specimen are proposed, based on which theoretical models of the strain transfer coefficients are established. It appears that the parabolic distribution of specimen strain should be more reasonable by comparison. Nevertheless, the strain transfer coefficients obtained by the theoretical models are higher than the measured coefficients. On this basis, a strain transfer model considering slippage at the interface of the sensing cable and the soil is discussed.

• 대한치과보철학회지
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• 제43권3호
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• pp.322-330
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• 2005

Statement of problem. In distal extension removable partial denture, the preservation of health of abutment teeth is very important, but abutment teeth are subjected to unfavorable stress. Purpose. The purpose of this study was to investigate the biomechanical effects of mandibular removable partial dentures with various prosthetic designs using strain gauge analysis. Material and methods. Artificial teeth of both canines were anchored bilaterally in a mandibular edentulous model made of resin. Bilateral distal extension removable partial dentures with splinted and unsplinted abutments were fabricated. Group 1 : Clasp-retained mandibular removable partial denture with unsplinted abuhnents Group 2 : Clasp-retained mandibular removable partial denture with splinted abutments by 6-unit bridge Group 3 : Bar-retained mandibular removable partial denture Strain gauges were bonded on the labial plate of the mandibular resin model, approximately 2 mm close to the abutments. Two vertical experimental loadings (100N and 200N) were applied subsequently via two miniature load cells that were placed at mandibular first molar regions. Strain measurements were performed and simultaneously monitored from a computer connected to data acquisition system. For within-group evaluations, t-test was used to compare the strain values and for between-group comparisons, a one-way analysis of variance (ANOVA) was used and Duncan test was used as post hoc comparisons. Results. Strain values increased as the applied load increased from 100N to 200N for all groups (p<.05). The strain values of group 1 and 2 were tensile under loadings. In contrast, strain values of group 3 were compressive in nature. Under 100N loading, group 1 showed higher strain values than group 3 in absolute quantity (p<.05). Under 200N loading, group 3 showed higher strain values than group 1 and 2 in absolute quantity (p<.05). Group 1 showed higher strain values than group 2 (p<.05). Conclusion. Splinting of two isolated abutments by bridge reduced the peri-abutment strain in comparison with unsplinted abutments. Strain of bar-retained removable partial denture increased much more as applied load increased, but was compressive in nature.

• 한국균학회지
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• 제12권2호
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• pp.65-73
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• 1984

Fusarium moniforme의 4가지 Strain중 Strain IV가 가장 병원성(病原性)이 강(强)하면서 유묘(幼苗)를 도장시키면서 고사(枯死)시키었다. 이병주(罹病株)는 Strain에 관계없이 밀양 23호와 남풍벼는 mesocotyl를 형성하였으나 삼남벼와 진주벼는 mesocotyl를 형성하지 않았다. Mesocotyl를 형성하는 밀양 23호와 남풍벼는 포장에서 건전화(健全化)되었으나 mesocotyl를 형성하지 않는 삼남벼와 진주벼는 대부분 고사(枯死)하였다. 이병(罹病)된 부위(部位)에서 병원균(病原菌)을 분리(分離)한 결과(結果)가 Strain IV가 가장많이 분리(分離)되었으며 분리부위(分離部位)는 벼전체에서 분리(分離)되었다. 키다리병출현(病出現)은 Strain IV에 이병(罹病)된것이 가장많이 본답(本畓)에서 키다리증상(症狀)을 보였으며 주당(株當)분얼수와 수량도 Strain IV에 이병(罹病)된 것은 상당히 감소 되는 경향이었다.

• 한국해양공학회지
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• 제25권3호
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• pp.73-84
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• 2011

This is the fifth in a series of companion papers dealing with the dynamic hardening properties of various marine structural steels at intermediate strain rates. Five steps of strain rate levels (0.001, 1, 10, 100, 200/s) and three steps of temperature levels (LT ($-40^{\circ}C$), RT, and HT ($200^{\circ}C$)) were taken into account for the dynamic tensile tests of three types of marine structural steels: API 2W50 and Classifications EH36 and DH36. The total number of specimens was 180 pieces. It was seen that the effects of dynamic hardening became clearer at LT than at RT. Dynamic strain aging accompanying serrated flow stress curves was also observed from high temperature tests for all kinds of steels. The dynamic hardening factors (DHFs) at the two temperature levels of LT and RT were derived at the three plastic strain levels of 0.05, 0.10, 0.15 from dynamic tensile tests. Meanwhile, no DHFs were found for the high temperature tests because a slight negative strain rate dependency due to dynamic strain aging had occurred. A new formulation to determine material constant D in a Cowper-Symonds constitutive equation is provided as a function of the plastic strain rate, as well as the plastic strain level. The proposed formula is verified by comparing with test flow stress curves, not only at intermediate strain rate ranges but also at high strain rate ranges.

• Earthquakes and Structures
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• 제10권5호
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• pp.989-1012
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• 2016

The structural dynamic behavior and yield strength considering both ductility and strain rate effects are analyzed in this article. For the single-degree-of-freedom (SDOF) system, the relationship between the relative velocity and the strain rate response is deduced and the strain rate spectrum is presented. The ductility factor can be incorporated into the strain rate spectrum conveniently based on the constant-ductility velocity response spectrum. With the application of strain rate spectrum, it is convenient to consider the ductility and strain rate effects in engineering practice. The modal combination method, i.e., square root of the sum of the squares (SRSS) method, is employed to calculate the maximum strain rate of the elastoplastic multiple-degree-of-freedom (MDOF) system under uniform excitation. Considering the spatially varying ground motions, a new response spectrum method is developed by incorporating the ductility factor and strain rate into the conventional response spectrum method. In order to further analyze the effects of strain rate and ductility on structural dynamic behavior and yield strength, the cantilever beam (one-dimensional) and the triangular element (two-dimensional) are taken as numerical examples to calculate their seismic responses in time domain. Numerical results show that the permanent displacements with and without considering the strain rate effect are significantly different from each other. It is not only necessary in theory but also significant in engineering practice to take the ductility and strain rate effects into consideration.

• Composites Research
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• 제31권6호
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• pp.429-434
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• 2018

본 연구에서는 구조물에 부착된 분포형 광섬유 센서의 변형률을 정밀하게 분석하기 위해 위치에 따른 변형률의 변화를 고려하여 광섬유 센서의 변형률 전달률을 분석하였다. 표면에 부착된 코팅된 광섬유 센서의 모델로부터 해석적으로 광섬유 센서의 변형률 전달률을 유도하였으며, 유도된 변형률 전달률은 유한요소해석을 통해 수치적으로 해석한 결과와 비교 검증하였다. 주 구조물의 변형률이 동일한 파장을 가지며 변하는 경우 센서의 변형률 전달률은 위치에 따라 동일한 값을 보였으며, 따라서 변형률 분포의 형상은 왜곡되지 않는다. 하지만 위치에 따라 변형률 파장이 변하면 변형률의 전달률이 위치에 따라 달라져 변형률 분포의 형상이 왜곡될 수 있음을 확인하였다. 본 연구를 통해 얻어진 파장에 따른 변형률 전달률은 분포형 광섬유 센서로부터 주 구조물의 변형률 분포를 정밀하게 추정하는데 유용하게 사용될 것으로 기대된다.

• 미생물학회지
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• 제20권3호
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• pp.125-133
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• 1982

Mutational experiments were performed to imporve the cellulase productivity of Aspergillus phoenicis KU175, isolated from the southern part of Korea, as a high cellulase producer. By treatment ultra-violet light nad 4-NQO(4-Nitroquinoline-N-Oxide), mutation waas induced, and treatment ultra-violet light and 4-NQO (4-Nitroquinoline-N-Oxide), mutation was induced, and A.phoenicis KU175-115 was finally selected for its highest avicelase production. Avicelase production of the mutant was increased about 2 times compared with those of the wild strain. However, activities of other hydrolytic enzymes, such as amylase, protease and nuclease, of the mutant strain didn't show a marked difference compared with those of the nuclease, of the mutant strain didn't show a marked difference compared with the wild strain, except slight increase in ribonuclease activity and slight decrease in glucoamylase activity. Avicelases from the mutant strain selected were purified from wheat bran culture by successive salting out, followed by dialysis and column chromatography, and their charcteristics were compared with thosw of the wild strain. Avicelase was separated into three peaks in the mutant strain as well as in the case of wild strain. Avicelase II activity of the mutant strain was prominently higher than that of the wild strain, while avicelase I and III activities of those were equivalent. The optimal pH ranges and stability of avicelase II from the mutant strain were pH4-5 and pH3.5-6.0, respectively, as well as in the case of the wild strain. The optimal temperature and thermal stability of avicelase II from the mutant strain were $40{\sim}50^{\circ}C\;and\;20{\sim}55^{\circ}C$, respectively. These results were same as those of the wild strain. By the using of Eadie-Hofastee plot, $K_m\;and\;V_{max}$ of avicelase II from the mutant and the wild strain were calculated to be 2.29mg/ml and $4.84{\mu}g$ reducing sugar as glucose per min equally, from the line fitted to the data by the least square method. Activity of avicelase II from the mutant strain was slightly activated by $Mg^{++}\;but\;inhibited\;by\;Cu^{++}, \;Mn^{++}\;and\;Zn^{++}$, as well as in the case of the wild strain. Therefore, it was concluded that the mutant didn't induce the formation of another avicelase isozyme, or the changes in the properties of avicelase, but induce the changes in the productively of the same avicelase II by the action of regulatory gane.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.435-438
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• 2000

토양으로부터 2종류 그리고 해양으로부터 1종류의 원유 분해 미생물을 분리하였고, 이들을 strain A132, strain F722 그리고 strain OM1으로 각각 명명하였다. 이들 미생물은 Acinetobacter sp., Pseudomonas aeruginosa, Acinetobacter calcoaceticus로 각각 동정되었다. Strain A132. F722의 최적 배양 및 분해온도는 $35^{\circ}C$ 이고, 최적 생장 pH는 각각 8과 9에서 나타났다. 원유를 유일한 탄소원으로 하여 배양을 하였을 때 원유농도 2.0%(w/v)에서 생장이 높았다. 한편, 해양에서 분리된 strain OM1은 pH 7, 원유농도 3.0%(w/v)에서 생장이 높았다. 원유 분해능 조사에서는 Eleuthera (OMAN) 원유를 2.0%(w/v) 기질로 하였을 때, strain A132가 $25^{\circ}C$에서 $5.49g/\;l\;{\cdot}\;day$의 분해능을 나타내었다. 반면, L-Zakum (AFRICA) 원유에서는 strain F722가 $35^{\circ}C$에서 $1.19g/\;l\;{\cdot}\;day$의 분해능을 보였다. 등유$(nC_9-nC_{20})$와 경유$(nC_9-nC_{28})$에 대하여 분해특성을 조사한 결과 strain OM1은 배양 7일 후 95, 75%를 각각 분해하였다. Strain F722는 배양10일 후 80%의 분해율을 나타내었다.

• 한국균학회지
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• 제11권4호
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• pp.169-175
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• 1983

벼키다리병(病)에 이병(罹病)된 벼에서 531균주를 분리(分離)하여 5가지 기준(基準)을 두고 분류(分類)한 결과(結果) Strain I, II, III과 IV로 분류(分類)한 수 있었다. 그중에서 Strain IV가 가장 많이 우리나라 분포(分布)되었으며 병원성도 강(强)한 것으로 나타났다. 5가지기준(基準)은 기주(寄主)의 병징(病徵), 포자형성(胞子形成), 대형분생포자격막수(大型分生胞子隔膜數), 균총의 색깔과 약제(藥劑)의 반응(反應)이었다. Strain I은 병원성(病原性)이 약하게 나타났으며 pionnotes안에 $6{\sim}7$개(個)의 격막(隔膜)을 가진 대형분생포자(大型分生胞子)를 형성(形成)하며 균총의 색깔은 표면(表面)과 이면(裏面)에 전부(全部) reddish purple을 보인다. Strain II는 병원성(病原性)은 약(弱)하나 pionnotes안에 소형분생포자를 형성(形成)하며 균총의 색깔은 표면(表面)과 이면(裏面)에 전부(全部) reddish purple을 보인다. Strain III는 병원성(病原性)이 강(强)하여 심하게 도장(徒長) 시키며 sporodochia안에 4개의 격막(隔膜)을 가진 대형분생포자(大型分生胞子)를 형성(形成)하며 균총의 색깔은 표면(表面)에는 yellowish red 이면(裏面)에는 reddish purple를 보인다. Strain IV은 병원성(病原性)이 강(强)하여 심하게 도장(徒長)시키기도 하고 고사(枯死)시킨다. sporodochia안에 주로 3개(個)의 격막(隔膜)을 가진 대형분생포자(大型分生胞子)를 형성(形成)하며 균총의 색깔은 표면(表面)과 이면(裏面) 전부(全部) yellowish red를 보이는 것이 특징이다.

• 한국세라믹학회지
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• 제46권1호
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• pp.86-93
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• 2009

The crack formation and the resistance of ITO film on PET substrate with a thickness of 20 nm were investigated as a function of strain. The onset strain for the increase of resistance increased with increasing strain rate, suggesting the crack initiation is dependent on the strain rate. Electrical resistance increased at the strain of 1.6% at the strain rates below $10^{-4}/sec$ while it increased at ${\sim}2%$ at the strain rates above $10^{-3}/sec$. The critical strain at which the cracks were formed is close to the proportional limit. Upon loading, the initial cracks perpendicular to the tensile axis were observed and propagated the whole sample width with increasing strain. The spacing between horizontal cracks is thought to be determined by the fracture strength and the interfacial strength between ITO and PET. The crack density increased with increasing strain. However, the effect of the strain rate on the crack density was less pronounced in ITO/PET with 20 nm ITO thickness than ITO/PET with 125 nm ITO thickness, the strength of ITO film is thought to increase as the thickness on ITO film decreases. The absence of cracks on ITO film at a strain as close as 1.5% can be attributed to the compressive residual stress of ITO film which was developed during cooling after the coating process. The higher critical strain for the onset of the resistance increase and the crack initiation of ITO/PET with a thinner ITO film (20 nm) can be linked with the higher strength of the thinner ITO film.