• 대한기계학회논문집A
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• 제24권7호
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• pp.1847-1853
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• 2000

A computer simulation technique for 2-dimensional laser generated ultrasonic waves was developed for visualization and investigation of ultrasonic propagation in solids. The technique is similar to a finite difference method (FDM) and a mass-particle model method, but uses a new nodal calculation method based on fundamental consideration of an elastic wave equation. By this method, the propagation behavior oflaser generated ultrasonic wave in thermoelastic and ablation mode is visualized and shows good agreement with previous experimental result or the numerical analysis result by Green function.

• Journal of Plant Biotechnology
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• 제6권3호
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• pp.165-169
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• 2004

The fruits of Vitex rotundifolia in Korea, known as 'Man Hyung Ja', occupy an important position as traditional oriental medicine in Asian countries. It is known that propagation of this plant by seed is difficult and time-consuming with little success. Attempts were made to develop a method by using nodal culture techniques. Explants of stem node without leaves cultured on Nitsch medium containing 1 ml/L BA, gave the best shoot induction ratio. Also, BA with IAA or TDZ treatment showed positive effect on shoot induction. Half-strength Nitsch medium was supplemented with 0.5 mg/L NAA produced better success than did the others on root formation. It showed that many of the regenerants grew successfully on growth chamber at $24^{\circ}c$.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.250-261
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• 1995

In this study, a rapid compression and expansion machine(RCEM) equipped with a swirl generator was designed and developed, in order to clarify normal and abnormal combustion(knocking phenomena). This RCEM is intended to simulate combustion process in actual automotive S.I.engines, having a high reproducibility in the compression stroke. Flame propagation and autoignition processes associated with normal and abnormal combustion were captured by the high speed schlieren photography. And swirl intensity. equivalence ratio and ignition position were varied to investigate the effect of turbulence, concentration in the unburnt gas region and flame propagation length. The knock intensity, knock mass fraction and knock mass fraction after autoignition were calculated by use of history of measured cylinder pressure.

• 대한조선학회논문집
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• 제44권5호
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• pp.488-495
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• 2007

In this paper, SBN (Structure-Borne Noise) reduction of resiliently mounted machinery and effect of the foundation impedance on mount performance is studied. SBN reduction through the mount is analyzed by using two theoretical models; mass-spring model and wave model, in which longitudinal wave propagation is included. It is found that floor impedance greatly affects SBN reduction through lower mount, while it is almost negligible to SBN reduction through upper mount. Comparisons between measurement and predictions shows that the mass-spring model is valid only in low frequency range below few hundred Hz, while for high frequency ranges longitudinal wave propagation in the mount must be considered.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2008년도 추계학술발표회
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• pp.70-70
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• 2008

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2001년도 추계정기 학술발표회 초록집
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• pp.111-113
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• 2001

• Earthquakes and Structures
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• 제3권1호
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• pp.17-35
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• 2012

Simplified equations for fundamental period of vibration of skeletal structures provided by most seismic design provisions suffer from the absence of any associated confidence levels and of any reference to their empirical basis. Therefore, such equations may typically give a sector of designers the false impression of yielding a fairly accurate value of the period of vibration. This paper, although not addressing simplified codes equations, introduces a set of mathematical equations utilizing the theory of error propagation and First-Order Second-Moment (FOSM) techniques to determine bounds on the relative error in theoretically calculated fundamental period of vibration of skeletal structures. In a complementary step, and for verification purposes, Monte Carlo simulation technique has been also applied. The latter, despite involving larger computational effort, is expected to provide more precise estimates than FOSM methods. Studies of parametric uncertainties applied to reinforced concrete frame bents - potentially idealized as SDOF systems - are conducted demonstrating the effect of randomness and uncertainty of various relevant properties, shaping both mass and stiffness, on the variance (i.e. relative error) in the estimated period of vibration. Correlation between mass and stiffness parameters - regarded as random variables - is also thoroughly discussed. According to achieved results, a relative error in the period of vibration in the order of 19% for new designs/constructions and of about 25% for existing structures for assessment purposes - and even climbing up to about 36% in some special applications and/or circumstances - is acknowledged when adopting estimates gathered from the literature for relative errors in the relevant random input variables.

• 한국자원식물학회지
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• 제6권2호
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• pp.171-179
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• 1993

This study was conducted to investigate the effect of growth regulators and medium composition on the growth of each stage in apical meristem culture for mass propagation of Zanthoxylum piperitum var. inerme Makino. The source material, shoot tip segments were taken from three-years old graft trees. Apical meristems were cultured in vitro on basal MS, GD, WS, half strength MS(1/2MS) and half strength GD(1/2GD) media supplemented with various concentrations for growth regulators(BA, IBA) and inorganic nutrients. The results summarized are as follows: 1. In culture establishment stage, ratio of culture establishment was 96.7% and the best resuit was obtained using MS medium supplemented with 1.0mg/l BA and 0.2mg/l IBA. 2. In shoot multitication stage, both shoot multiplication and growth were achieved in average 5.6cm. These results were obtained on in MS medium supplemented with 1.0mg/l BA and 0.2mg/l IBA. 3. In roothing stage, phloroglucinol(PG) acted as IBA synergist in root initiation. The most faverable combinations for root development was half-strength MS medium supplemented with 162mg/l PG and 0.2mg/l IBA, and ratio of rooting was 58.0%. 4. In Vitro formed plantlets were transplanted to paper pots in greenhouse with 85% of relative humidity. 96% of survival rate was obtained from artificial soil mix having same volume of sand, vermiculite, peat, and soil.

• 한국산림과학회지
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• 제90권2호
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• pp.184-189
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• 2001

제주 자생 왕벚나무 동아에서 분화된 줄기를 이용하여 대량증식 하고자 기내배양조건을 구명하였다. 다섯 종류의 배지에서 모두 양호한 생장을 하여 차이가 나타나지 않았으나 sucrose가 첨가되지 않은 배지에서는 생장이 매우 저조하였다. BAP와 $GA_3$를 여러 농도로 처리한 결과 BAP 처리구에서 평균 3.5~9.5개의 줄기가 유도되었다. 그러나 BAP의 농도가 높아질수록 줄기의 길이생장은 저조하였다. $GA_3$ 단독 처리구에서는 줄기가 발생하지 않았으나 BAP와 혼용처리 하였을 때 BAP 단독 처리구보다 더 많은 줄기가 발생하였으며, 길이 생장도 양호하였다. 그 중 BAP $0.5mg/{\ell}$와 $GA_3$ $4.0mg/{\ell}$ 조합에서 가장 많은 줄기가 발생하였다. 배양기간이 경과할수록 줄기형성은 많아졌으나 12주간 배양된 줄기는 정단부가 고사하였다. 배양 8주째 양호한 줄기를 다량으로 얻을 수 있었다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2000년도 The 7th International Symposium
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• pp.114-115
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• 2000

Aralia elata is found in mountain areas all over Korean peninsula. Aralia elata is the scientific name for Japanese angelica tree. The tree belongs to the family Araliaceae, commonly known as ginseng family. Bud sprouts from apical shoot tip of the plants are rich in flavor and thus mainly used for both folk medicine and vegetable. The stalks with apical buds are gathered in the early spring and planted in sandy soil or water in the greenhouse. The sprouting buds are then collected and sold as fresh vegetable. Although the plants have been used for food, they have been cultivated in a very small scale. In spring, local farmers just go around mountain areas to search the trees and gather the stalks as much as they get and sell them to the market. No conservation efforts have been made to stop the exploitation or to save the dwindling population. We tried to provide local farmers with the plants that may be used as an alternative to stalks from wild populations. This will bel! p conserve the wild populations. However, it is hard to propagate them either by conventional cuttings or by seed germination in a short period of time. Mass propagation using tissue culture systems have shown a great promise with several woody plants. Recently we developed a mass propagation technique via somatic embryogenesis system using mature and/or juvenile explants for Aralia elata. Several factors affecting somatic embryogenesis system including SE(somatic embryo) induction, embryogenic callus proliferation, SE germination, plant regeneration and transplanting to field frill be presented. And some problems arising for the somatic embryogenesis system will be also discussed.