• 대한방사선방어학회:학술대회논문집
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• 대한방사선방어학회 2011년도 추계 학술발표회 및 심포지엄
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• pp.102-103
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• 2011

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.538-541
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• 2005

Most realistic control systems contain nonlinearities of some form. One nonlinearity commonly found in control systems is a saturating element. If integral control is applied to such a system to eliminate steady state error, an undesired side effect known as integrator windup may occur when lage setpoint changes are made. This effect leads to a characteristic step response with a large overshoot and a very high settling time. To avoid this situation, many different anti-windup strategies have been suggested. But existing strategies remain over shoot and high settling time. This paper proposes a new anti-windup strategy for PI speed controllers. When the speed control system is changed P controller to PI controller. Integrator has an appropriate initial value. This value results over shoot and high settling time. The SIMULINK/MATLAB-based comparative simulation results and experiment results of speed controller have shown its superior control performance to that of a proposed anti-windup speed controller.

• Plant Biotechnology Reports
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• 제5권2호
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• pp.187-195
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• 2011

The gesneriaceous perennial plant Titanotrichum oldhamii has beautiful foliage and attractive bright yellow flowers. However, breeding of T. oldhamii by conventional sexual hybridization may be difficult because sexual reproduction of this species is very rare. In the present study, plant regeneration systems via both direct and indirect formation of adventitious shoots from leaf explants were established as the first step toward breeding T. oldhamii by using biotechnological techniques. Adventitious shoots were formed efficiently on medium containing $0.1mg\;l^{-1}$ benzyladenine. Histological observation showed that shoot formation on this medium occurred directly from leaf epidermal cells without callus formation. On the other hand, leaf explants formed calluses on medium containing $0.1mg\;l^{-1}$ 2,4-dichlorophenoxyacetic acid. The calluses could be maintained by monthly subculturing to fresh medium of the same composition. When the calluses were transferred to plant growth regulator-free medium, they formed adventitious shoots. Directly and indirectly formed shoots rooted well on medium containing $0.1mg\;l^{-1}$ indole-3-butyric acid. Plantlets thus obtained were successfully acclimatized and grew vigorously in the greenhouse. Flow cytometry analysis indicated that no variation in the ploidy level was observed in plants regenerated via direct shoot formation, whereas chromosome doubling occurred in several plants regenerated via indirect shoot formation. Regenerated plants with the same ploidy level as the mother plants showed almost the same phenotype as the mother plants, whereas chromosome-doubled plants showed apparent morphological alterations: they had small and crispate flowers, and round and deep green leaves.

• 한국산림과학회지
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• 제86권4호
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• pp.430-434
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• 1997

희귀 수종인 산개나리(3년생)의 산초지 액아를 배양하여 식물체를 유도하였다. 효과적인 증식법 구명을 위해 MS 배지에서 세 가지 싸이토키닌(BAP, kinetin, zeatin)의 농도별 효과를 조사하였다. 증식은 식물 생장조절 물질이나 농도별 효과가 뚜렷하지 않았으나 zeatin 처리시 줄기 및 잎의 발달에 효과가 있었다. kinetin 처리는 줄기 생장과 더불어 모두 발근되는 특징을 보였고, BAP와 zeatin은 발근은 가능하나 고농도로 갈수록 발근율이 감소하였다. 황화처리는 줄기의 생장을 촉진하였다. 줄기는 3년 이상의 계대배양 후에도 정상적인 증식이 가능했다. 발근된 식물체는 인공 배양토에서 100% 활착되었으며 산지에 이식하여 정상 생장하였다. 이상의 결과는 희귀 수종인 산개나리의 기내 번식으로 자생지의 복원이 가능함을 시사한다.

• 한국연초학회지
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• 제15권2호
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• pp.130-136
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• 1993

Protoplasts of palisade cells were aseptically isolated from leaves of Nicotiono apicona Merxm. by the one step enzymatic method. Efficiency of colony formation were depended on cell density and light condition during incubation, but an intensity of 47 ft-c during a period of 2 weeks after isolation of the protoplasts in the Nagata and Takebe's medium promoted the planting efficiency. Protoplast - derived calli of N. africana can be differentiated into shoot when cultured on Murashige and skoog's medium containing IAA(0.Smg/$\ell$) and zeatin(5.0mg/$\ell$).

• Journal of Radiation Protection and Research
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• 제46권2호
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• pp.48-57
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• 2021

Background: In this study, the complexities of step-and-shoot intensity-modulated radiation therapy (IMRT) plans in magnetic resonance-guided radiation therapy systems were evaluated. Materials and Methods: Overall, 194 verification plans from the abdomen, prostate, and breast sites were collected using a ⁶⁰Co-based ViewRay radiotherapy system (ViewRay Inc., Cleveland, OH, USA). Various plan complexity metrics (PCMs) were calculated for each verification plan, including the modulation complexity score (MCS), plan-averaged beam area (PA), plan-averaged beam irregularity, plan-averaged edge (PE), plan-averaged beam modulation, number of segments, average area among all segments (AA/Seg), and total beam-on time (TBT). The plan deliverability was quantified in terms of gamma passing rates (GPRs) with a 1 mm/2% criterion, and the Pearson correlation coefficients between GPRs and various PCMs were analyzed. Results and Discussion: For the abdomen, prostate, and breast groups, the average GPRs with the 1 mm/2% criterion were 77.8 ± 6.0%, 79.8 ± 4.9%, and 84.7 ± 7.3%; PCMs were 0.263, 0.271, and 0.386; PAs were 15.001, 18.779, and 35.683; PEs were 1.575, 1.444, and 1.028; AA/Segs were 15.37, 19.89, and 36.64; and TBTs were 18.86, 19.33, and 5.91 minutes, respectively. The various PCMs, i.e., MCS, PA, PE, AA/Seg, and TBT, showed statistically significant Pearson correlation coefficients of 0.416, 0.627, -0.541, 0.635, and -0.397, respectively, with GPRs. Conclusion: The area-related metrics exhibited strong correlations with GPRs. Moreover, the AA/Seg metric can be used to estimate the IMRT plan accuracy without beam delivery in the ⁶⁰Co-based ViewRay radiotherapy system.

• 한국약용작물학회지
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• 제12권5호
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• pp.428-435
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• 2004

Alkaloid producing species of plants have long been a major component of the medicinal social and magico-religious aspects of human culture. A diverse array of biological activities has been attributed to different alkaloids including numerous members of benzylisoquinoline family of alkaloids. For biotechnological approaches of alkaloid biosynthesis in poppy family, plant regeneration protocol through somatic embryogenesis or shoot organogenesis is a first step. This paper describes the methods and applications of plant regeneration of poppy family.

• Plant Biotechnology Reports
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• 제2권2호
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• pp.123-131
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• 2008

Vitrification methods are convenient for cryopreserving plant specimens, as the specimens are plunged directly into liquid nitrogen (LN) from ambient temperatures. However, tissues and species with poor survival are still not uncommon. The development of vitrification solutions with high survival that cover a range of materials is important. We attempted to develop new vitrification solutions using bromegrass cells and found that VSL, comprising 20% (w/v) glycerol, 30% (w/v) ethylene glycol, 5% (w/v) sucrose, 10% (w/v) DMSO and 10 mM $CaCl_2$, gave the highest survival following cryopreservation, as determined by fluorescein diacetate staining. However, the cryopreserved cells showed little regrowth, for unknown reasons. To check its applicability, VSL was used to cryopreserve gentian axillary buds and the performance was compared with those of conventional vitrification solutions. Excised gentian stem segments with axillary buds (shoot apices) were two-step precultured with sucrose to induce osmotic tolerance prior to cryopreservation. Gentian axillary buds cryopreserved using VSL following the appropriate preculturing approach exhibited 78% survival (determined by the regrowth capacity), which was comparable to PVS2 and PVS1 and far better than PVS3. VSL had a wider optimal incubation time (20-45 min) than PVS2 and was more suitable for cryopreserving gentian buds. The optimal duration of the first step of the preculture was 7-11 days, and preculturing with sucrose and glucose gave a much higher survival than fructose and maltose. VSL was able to vitrify during cooling to LN temperatures, as glass transition and devitrification points were detected in the warming profiles from differential scanning calorimetry. VSL and its derivative, VSL+, seem to have the potential to be good alternatives to PVS2 for the cryopreservation of some materials, as exemplified by gentian buds.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2023년도 임시총회 및 춘계학술대회
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• pp.33-33
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• 2023

Potatoes are the world's 4th major food crop after maize, rice, and wheat and also are a staple food for 1.3 billion people. Due to their wide adaptability to various environmental conditions, their yeild capacity, and high commercial value, potatoes have contributed to global food security. Many potato germplasms are commonly preserved as whole plants in fields or in storage to maintain their particular genetic combinations. However, field maintenance is expensive and has the risk of potential losses from diseases, pests, plant ageing and climate change. Over the past four decades, meaningful efforts have been made toward the safe long-term conservation of potatoes through cryopreservation methods such as droplet-vitrification. In this study, we tested 4 Korean potato varieties('Golden Egg', 'Golden Ball', 'Ja-Young' and 'Ha-Ryeong') with the modified potato droplet -vitrification protocol. Potato shoot tips are precultured in a sucrose-enriched medium(0.3 and 0.7M for 7 and 17hrs, respectively) and submitted to a loading step with C4 solution for osmoprotection. The treated explants were dehydrated with Plant Vitrification Solution(PVS)2 which is 80% A3 solution in ice for 30 minutes. Thawing and unloading steps were performed with 0.8M sucrose solution for 30 sec(40℃) followed by 30min(25℃, room temperature). In a potato post-culture medium(MS+0.1 mg·L^-1 GA₃+0.1 mg·L^-1 kinetin), we obtained a survival rates of post-thawed explants ranging 16.1-82.2%. The results suggest that modified and optimized protocols are required dependinig on every cultivar, genetic and ecological types. To achieve higher survival and regeneration rates, each step within the cryoprocedure must be carefully optimized.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.838-848
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• 2018

This paper proposes a single-phase buck-boost AC-AC converter. It consists of three legs with six switching units (each unit is composed of an active switch and a diode) and its input and output ports share a common ground. It can provide buck-boost voltage operation and immune from shoot-through problem. Since only two switching units are involved in the current paths, the conduction losses are low, which improves the system efficiency. The operation principle of the proposed circuit is firstly presented, and then, various operation conditions are introduced to achieve different output voltages with step-changed frequencies. Additionally, the parameters design and comparative analysis of the power losses are also given. Finally, experimental results verify the correctness of the proposed converter.