• Journal of Power Electronics
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• 제18권3호
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• pp.702-713
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• 2018

Power loss reduction and total harmonic distortion(THD) minimization are two important goals of improving three-level inverters. In this paper, an optimized pulse width modulation (PWM) strategy that can reduce switching losses and balance the neutral point with an optional THD of three-level neutral-point-clamped inverters is proposed. An analysis of the two-level discontinuous PWM (DPWM) strategy indicates that the optimal goal of the proposed PWM strategy is to reduce switching losses to a minimum without increasing the THD compared to that of traditional SVPWMs. Thus, the analysis of the two-level DPWM strategy is introduced. Through the rational allocation of the zero vector, only two-phase switching devices are active in each sector, and their switching losses can be reduced by one-third compared with those of traditional PWM strategies. A detailed analysis of the impact of small vectors, which correspond to different zero vectors, on the neutral-point potential is conducted, and a hysteresis control method is proposed to balance the neutral point. This method is simple, does not judge the direction of midpoint currents, and can adjust the switching times of devices and the fluctuation of the neutral-point potential by changing the hysteresis loop width. Simulation and experimental results prove the effectiveness and feasibility of the proposed strategy.

• 한국진공학회지
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• 제17권2호
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• pp.96-101
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• 2008

MgO는 플라즈마 디스플레이 패널 (Plasma Display Panel, PDP)의 보호막으로 널리 쓰이고 있다. 기존의 산소 이온빔 보조 증착(Ion-Beam-Assisted Deposition, IBAD) 방법을 이용하여 MgO 보호막을 형성시킨 경우 이온빔의 충전에 의해 야기되는 아크(Arc) 문제 등이 있었다. 이 문제점을 해결하기 위하여, 산소 중성빔 보조증착(Neutral-Beam-Assisted Deposition, NBAD) 방법을 이용하여 MgO를 증착하였다. 그리고 산소 중성빔의 에너지를 변화시킴에 따라 MgO 보호막의 특성과 PDP 패널 방전 특성에 미치는 영향을 분석하였다. 이에 따른 실험 결과로부터 산소 중성빔 에너지가 300eV일 때, 최소 방전 개시 전압, 최고 발광 휘도 및 최고 발광 효율을 얻을 수 있었다.

• Korea-Australia Rheology Journal
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• 제19권2호
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• pp.51-59
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• 2007

A polyelectrolyte chain confined in a slit nanochannel exhibits a structural transition from the one in free space. In this paper, the effect of the long-range electrostatic interactions between the xanthan polyelectrolyte and the slit wall on the confined xanthan conformation is investigated via the Brownian dynamics simulation. A neutral and two negatively charged surfaces of polydimethylsiloxane (PDMS) and glass are combined to make four kinds of slit channels with different charge characteristics: i) neutral-neutral, ii) glass-glass, iii) neutral-PDMS and iv) neutral-glass walls. Their walls are characterized by uniform surface charge densities determined from experimental data of zeta potential. Both the nonmonotonic chain size variation and the loss of long-range bond vector correlation, previously observed under confinement in the PDMS-PDMS slit, are also found in the neutral slit, demonstrating the nonelectrostatic origin of such crossover behaviors. As expected, the effect of wall charges is negligible at sufficiently high medium ionic strength of 100mM but it becomes significant in the opposite limit of 0.01mM. In the latter case, the high charge density of glass walls strengthens the effective confinement of a negatively charged polyelectrolyte and produces a xanthan structure comparable to that confined in a much narrower neutral slit. The obtained structural data suggest the possibility of controlling the structure of confined polyelectrolytes by the modification of surface charge characteristics of micro/nanofluidic devices in combination with the adjustment of the medium ionic strength.

• 한국식품과학회지
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• 제21권1호
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• pp.17-24
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• 1989

가열처리 및 건조방법이 새우의 지방질 함량과 중성지방질에 미치는 영향을 밝히고자 하였다. 생새우의 총지방질 함량은 건물기준으로 6.0%였으며, 가열 및 건조방법에 따라 총지방질의 함량은 유의적인 변화가 없었다. 생새우의 중성, 당 및 인지방질의 함량비는 각각 36.8:21.5:41.7% 이었고 동결건조한 것은 열풍건조한 것보다 중성시방질의 함량이 유의적으로 많은 반면에 당 및 인지방질의 함량은 적었다. 중성지방질의 주요성불은 triglyceride, free sterol, free fatty acid 및 esterified sterol이었으며, 동결건조한 것은 열풍건조한 것보다 triglyceride 함량은 유의적으로 많았고 free fatty acid 함량은 적었는데, 이는 열풍건조중 triglyceride가 분해된 것으로 생각되었다. 생새우의 총지방질의 구성 주요지방산은 palmitoleic acid, eicosapentaenoic acid 및 docosahexaenoic acid이었고, 중성지방질의 구성 주요 지방산은 palmitic acid, palmitoleic acid, oleic acid, eicosapentaenoic acid 및 docasahexaenoic acid이었다.

• 구강회복응용과학지
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• 제17권2호
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• pp.107-112
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• 2001

The prosthodontic treatment of severely resorbed edentulous patients has been one of the frustrating areas due to extensive loss of tissues. The integrated neuromuscular balance among tongue, lip, and cheek is compromised. The retention, stability, and support are the three major factors to influence the clinical outcome. Fish described a denture as having three surface, with each surface playing an independent and important role in the over all fit, stability, and comfort of the denture. He recommended that the polished surface should be a series of inclines so that pressure from muscular activity will retain dentures. Within the denture space there is an area that has been termed the neutral zone. The neutral zone is that area in the mouth where, during function, the forces of the tongue pressing outward are neutralized by the forces of the cheeks and lips pressing inward. According to Jacobson and Krol, neuromuscular control interacts to provide retention and the relationship of polished surface of denture base to the surrounding muscular structure of orofacial capsule facilitates the stability and retention. This neutral zone concept has been demonstrated with various modification by a number of authors. The theory used to develop the denture base contours is based on the belief that the muscle should functionally mold not only the border but the entire polished surface. Lott and Walsh reported the clinical success on complete mandibular dentures with application of neutral zone concept. A number of studies demonstrated that denture stability and retention are more dependent on correct position of the teeth and correct contour of external surfaces of the denture in a severely resorbed alveolar ridge. This article presents a prosthodontic approach to treatment of a edentulous patient using neutral zone technique to improve the retention and stability of the prosthesis.

• 복식문화연구
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• 제18권5호
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• pp.789-808
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• 2010

The orientalism in fashion is believed to develop from the eclectic notion of oriental and occidental fashion. By studying on Gabrielle Chanel's clothing that is usually used by neutral colors and on Yohji Yamamoto's clothing that characterizes clothes in neutral colors, the purpose of this study is to seek ways for remaking Korean traditional clothing into a new modern one to gain a world reputation in terms of clothes. Therefore the study is for exploring the characteristics on the factors of fashion design such as color, line and textile materials with works of Gabrielle Chanel, a famous designer in Western world who has made a black color a popular one for people and works of Yohji Yamamoto, an well-known fashion designer of the East using neutral colors. This study analyzed, from the 2004 S/S to the 2006 F/W, the collection of works published in style.com through the works of Gabrielle Chanel, Yohji Yamamoto, and through the analysis of the visual target. A total of 527 images are used in this paper. Elements of fashion design analysis are lines, colors, and materials. The study reached the conclusion as follows after analyzing the characteristics on clothing with neutral colors of Gabrielle Chanel and Yohji Yamamoto. In case of aesthetic characteristics on the design of Gabrielle Channel, it has expression of feminist, sensual, modern and luxury. It is considered that Gabrielle Channel has a luxury image using a neutral color. Also using simple sleeveless in black and tweed structure, the garments have mixed with neutral colors. Fashion design characteristics on the design of Yohji Yamamoto classified into sensual, modern, ascetic expression. Therefore the design has a simple expression of using a black color. Yohji Yamamoto is a designer who pursues unstructured design by using various neutral colors such as black, gray and white based on the oriental sentiment.

• 한국식품과학회지
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• 제28권2호
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• pp.207-211
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• 1996

일반계 및 다수게 미강유의 지방질 함량과 중성 지방질 조성을 분석하고자 하였다. 조지방의 함량은 다수계 미강이 19.5-20,7%로서 일반계 미강보다 약 4-5%높았고, 미강유중의 중성. 당 및 인지방질의 평균 함량비는 일반계 미강유에서는 89.5 : 4.0.6.5%이었고, 다수계 미강유에서는 93.7: 2.6 : 3.7%이었다. 즉, 중성 지방질의 함량은 다수계 미강유가 일반계 미강유보다 유의적으로 많았다. 증성 지방질은 주로 esterified sterol, triglyceride, free fatty acid, free sterol, diglyceride및 monoglyceride로 되어 있었다 중성 지방질중에는 triglyceride가 48.7-49.7%. 가장 함량이 많았고, 다음으로는 free fatty acid가 26.7-27.8%로 많은양이 존재하고 있었다. 일반계 및 다수계 미강유의 주요 구성 지방산은 palmitic acid 등 3가지로 총 지방산의 95% 이상을 차지하고 있으며 그 중에서 oleic acid의 함량이 가장 높고, 그 다음은 linoleic, palmitic acid의 순이었다.

• 대한통합의학회지
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• 제5권1호
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• pp.67-74
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• 2017

Purpose : Forward head posture is typical neck disorders occur in all people. And this attitude causes a shortening and weakening of the muscles in the body. It also causes excessive extension acts as a reward. This attitude has to change if the pain occurs around the neck and shoulders, and are subjected to unusual stress. Patients with chronic neck pain associated with forward head posture was found to be the more severe the fall of the respiratory, forward head posture poor quality of much breath. The purpose of this study was to compare the effect of changes in forward head posture and neutral head posture on respiratory. Method : Forty volunteers were participated in study and divided into two groups [forward head posture group (n=20) and neutral head posture group (n=20)]. We measured cervical alignment with global postural system to find out a forward head posture. Respiratory function was measured with a SPIROVIT SP-1 equipment and we found out a forced vital capacity (FVC), forced expiratory volume at one second (FEV1) and FEV1/FVC. A pared t-test was used to determine a statistical significance for the pulmonary function variation and a independent t-test was used to determine a statistical significance in the two groups. Results : In the experimental group, FVC and FEV1 were significantly higher in the artificial neutral head posture than in the forward head posture. In the control group, FVC and FEV1 were significantly higher in the neutral head posture than in the forward head posture. FVC, FEV1, and FEV1/ FVC were significantly higher in the neutral head posture of control group than the artificial neutral head posture of experimental group and higher in the artificial forward head posture of control group than the forward head posture of experimental group. Conclusion : In conclusion, neutral head posture is considered to be an important factor in correct posture and improvement of lung function and continuous study of posture correction program for posture imbalance will be needed.

• 한국식품과학회지
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• 제13권1호
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• pp.30-36
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• 1981

우리 나라에서 재배된 4가치 품종의 보리와 이들의 맥아를 클로로포름-메탄올-물로 추출한 총지방질중 중성지질의 조성을 관, 얇은막 및 기체-액체 크로마토그래피로 분석한 결과를 요약하면 다음과 같다. 1. 4가지 품종의 보리와 이들 맥아중의 총지방질의 평균함량은 각각 3.3% 및 2.9%였으며, 보리중의 총지방질은 맥아에서 평균 12.2%가 감소되었다. 2. 보리와 맥아중의 총지방질중 중성지질의 평균함량은 각각 73.8% 및 68.5%였으며, 보리중의 중성지질은 맥아에서 평균 7.2%가 감소 되었다. 3. 보리의 중성지질중 트리-글리세리드와 유리지방산의 평균함량은 각각 57.5% 및 15.4%였으나 맥아에서 트리-글리세리드의 양은 감소하였으나, 유리지방산의 양은 증가하였다. 그 외에 sterol ester, free sterol, 1,3 및 1,2-diglyceride가 보리와 맥아의 중성지질중 부성분으로 함유되어 있었으며, 맥아중의 이들 neutral non-triglyceride fraction의 함량은 보리에서 보다 증가하는 경향이었다. 4. 보리와 맥아의 총지방질의 주된 지방산은 리놀레산, 팔미트산및 올레산이었으며, 맥아는 보리보다 포화지방산의 함량은 증가하는데 반하여 불포화 지방산의 함량은 감소하는 경향이 었다.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.738-750
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• 2017

In this paper, carrier-based pulse width modulation (CBPWM), space vector PWM (SVPWM) and reduced switching losses PWM (RSLPWM) for the three-level neutral point clamped (NPC) inverter are introduced. In the case of the neutral point (NP) potential (NPP) offset, an asymmetric disposition PWM (ASPDPWM) strategy is proposed, which can output PWM sequences correctly and suppress the lower order harmonics of the inverter effectively. An NPP balance strategy based on carrier based PWM (CBPWM) is analyzed. A hybrid modulation strategy combining RSLPWM and the NPP balance based on CBPWM is proposed, and hysteresis control is adopted to switch between the two modulation strategies. An experimental prototype of the three-level NPC inverter is built. The effectiveness of the hybrid modulation is verified with a resistance-inductance load and a permanent magnetic synchronous motor (PMSM) load, respectively. The experimental results show that reduced switching losses and an acceptable NPP can be effectively achieved in the hybrid modulation strategy.