• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.199-202
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• 2002

In general, the background light produced during the reset period deteriorates the dark room contrast ratio in AC PDP. In this paper, we propose a modified ramp reset pulse that can reduce the background light to imperceptible level. In the new reset waveform, the discharges between the scan and sustain electrodes are minimized by applying a positive bias voltage to the sustain electrode and only the weak discharges between the scan and address electrodes occur during the reset period. We adopted a MgO coated phosphor layer to get the same level of voltage margin in the new reset pulse scheme compared to that of the conventional ramp reset pulse one. As a result, the voltage margin is maintained at the same level and the dark room contrast ratio is improved dramatically.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2014년도 추계 종합학술대회 논문집
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• pp.411-412
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• 2014

The objective of this study was to evaluate relationships between the economic status and the oral health status. Data were obtained from the National Health Insurance Corporation database. The prevalence of dental caries and tooth loss were compared among the ten-percentile according to the level of the monthly income. The prevalence of dental caries and tooth loss were lower in the high level of monthly income than low level of monthly income group. There was a significant relationships between the economic status and the oral health status.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권3호
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• pp.319-329
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• 2016

High-level design aids are mandatory for design of a continuous-time delta-sigma modulator (CTDSM). This paper proposes a top-down methodology design to generate a noise transfer function (NTF) which is compensated for excess loop delay (ELD). This method is applicable to low pass loop-filter topologies. Non-ideal effects including ELD, integrator scaling issue, finite op-amp performance, clock jitter and DAC inaccuracies are explicitly represented in a behavioral simulation of a CTDSM. Mathematical modeling using MATLAB is supplemented with circuit-level simulation using Verilog-A blocks. Behavioral simulation and circuit-level simulation using Verilog-A blocks are used to validate our approach.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1134-1135
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• 2007

In this paper, we proposed the isolated multi-level inverter using 3-phase transformers. It makes possible to use a single DC power source due to employing low frequency transformers. In this inverter, the number of transformer could be reduced comparing with an exiting 3-phase multi-level inverter using single phase transformer. Also, using phase angle control method with switching frequency equal to output fundamental frequency, harmonics component of output voltage and switching losses can be reduced. Finally, we made a prototype inverter to clarify the proposed electric circuit and reasonableness of control signal.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.476-477
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• 2012

단상 풀브릿지 인버터는 직류전원에서 가변 주파수 전압을 발생시키는 전력변환기다. 또한 이를 근본으로 많은 곳의 산업현장에 응용되며 실제 가정생활이나 신재생 에너지의 변환 장치로 많이 사용된다. 또한 많은 MCU의 발달로 인해 PWM변조 방식의 인버터가 개발되는 상황이다. 이러한 경우 기존의 단상 풀 브릿지 인버터의 THD는 3-LEVEL로 THD의 특성 개선의 한계가 있는 것이 현재의 상황이다. 본 논문에서는 단상 풀브릿지의 인버터를 기본으로 개선된 토폴로지를 구현하여 THD의 특성을 한 단계 높인 방법을 제안하고자 한다.

• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.27-32
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• 1997

The geometries and energies of the isomers in alkyne complexes MCl(PH3)2(η2-C2H2), M=Rh and Ir, are theoretically investigated using ab initio methods at the Hartree-Fock and up to MP4 level of theory and relativistic effective core potentials for Rh and Ir metals. The optimized structures of Rh complexes, 1-3 at MP2/ECP1 level are in good agreement with the related experimental data. The binding energies of C2H2 to d8-metal fragments are computed to be ∼55 kcal/mol. The vinylidene complexes for Rh and Ir metals are calculated to be much lower in energy than the alkyne complexes. The alkyne-vinylidene rearrangement is possible to proceed exothermically through the intermediate hydrido-alkynyl complexes, 2 or 9. Detailed comparison is given about the geometries and relative energies on Rh and Ir isomers at the various level ab initio calculations with orbital analysis.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.403-404
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• 2020

본 논문에서는 단일 2-level 3-leg 전압형 인버터를 사용하여 직렬 연결된 3상 및 단상 표면부착형 영구자석 동기전동기(SPMSM)를 가변속 운전하는 기법을 제안한다. 일반적으로 두 영구자석 동기전동기를 독립적으로 가변속 운전하기 위해서는 각각의 인버터가 필요하지만, 본 논문은 옵셋(Offset) 전압을 사용한 전압 펄스 폭 변조(PWM) 방식으로 인버터를 제어하여 단일 인버터를 사용한 3상 및 단상 전동기 동시 운전이 가능하다. 제안된 방식은 전력용 반도체 소자 수를 줄여 전동기 구동시스템의 가격을 절감시킬 수 있으며, PLECS 시뮬레이션을 통하여 제안된 토폴로지의 유효성을 검증하였다.

• Journal of Periodontal and Implant Science
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• 제29권1호
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• pp.41-49
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• 1999

The purpose of this study was to evaluate the relationship between osteoporosis and periodontal condition in postmenopausal women. Twenty-eight patients who have been treated at Chonnam national university hospital with osteoporosis(osteoporotic group, mean $age62.2{\pm}6.6$) and 21 normal postmenopausal women with periodontitis(control group, mean $age60.4{\pm}3.7$) were examined. Bone mineral density(BMD) of lumbar spine(L2-L4) was measured by dual energy X-ray absorptiomemtry(DEXA). Percentage to peaked bone mass in osteoporotic group was 70.9% which had lower BMD than in control group(p<0.05). The number of present teeth were 23.6 in osteoporotic group and 23.1 in control group. Percentage of bleeding on probing was 41% in osteoporotic group and 37% in control group. probing depth and attachment level were shown 3.18 mm, 3.63 mm in osteoporotic group and 2.85mm, 3.11mm in control group, respectively. Probing depth and attachment level were significantly greater in osteoporotic group than in control group(p<0.05). The significant negative correlation was found between BMD level and periodontal attachment level(p<0.001, ${\gamma}=-0.56$). These results suggest that osteoporosis may be associated with periodontal breakdown.

• Journal of Preventive Medicine and Public Health
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• 제31권4호
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• pp.844-856
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• 1998

Globally, cancer research has been considered one of the most important field of biomedical researches. Recently, in Korea, there are increasing concerns about cancer research and the development of national cancer control programme. For the efficient investment in cancer research at the national level, strategic approach is needed based on the nationwide information about current status of research. However even the basic data on cancer research have not been systematically collected, and are not available when necessary. The aim of this study is to assess current status of cancer research. For this purpose, this study applied two round Delphi method in which fifteen experts in cancer research fields participated. They rated each items on the initial list at the first round, and modified their responses at the second round. Panels responded that pathogenesis of cancer, research & development of cancer drug, and oncogene, etc. are the most urgent and important research Holds. They assessed national level of cancer research as being 49.6% of the world highest level. Coefficient of variation tended to be lowered with the iteration. Predictive stability was evaluated to be lower in items of urgency than in items of importance and research level. Although this study shares the same limitations in the selection of the experts with many other Delphi studies, it provides a primary data that would be required to plan the national strategy of the cancer research.

• 원예과학기술지
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• 제35권2호
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• pp.276-286
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• 2017

Licorice, a traditional Korean medicinal plant, is recognized for its main active ingredient, glycyrrhizin. The level of glycyrrhizin in Chinese licorice (Glycyrrhiza uralensis) is lower than the reference level (2.5%) set by the Korean Pharmacopoeia, reducing its value as a medicinal herb. In this study, we aimed to overcome this problem by generating an interspecific licorice hybrid by crossing European licorice (G. glabra) with Chinese licorice, resulting in the production of 32 $F_1$ lines. A comparison of genetic traits revealed variations in glycyrrhizin content among lines, ranging from 1.5 to 5.6%, with a mean value of 3.2%; these values are higher than that of the parental plants. Additionally, 25 lines (78.1%) had a glycyrrhizin content greater than 2.5%, which is higher than the reference level set by the Korean Pharmacopoeia. Four of these lines had glycyrrhizin levels higher than the WHO recommended level of 4.0%. A comparison of phenotypic characteristics showed that the leaves of the hybrids possessed all of the characteristics of European and Chinese licorice; however, the stems of most hybrids had characteristics of European licorice. Finally, we determined the genetic distances of 34 samples of Glycyrrhiza plants (parents, 32 $F_1$ lines) by random amplified polymorphic DNA (RAPD); the $F_1$ lines showed a close genetic distance. We plan to develop to a cultivar using five of these lines (glycyrrhizin content < 4.0%).