• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.4
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• pp.333-342
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• 2009

Three-level Diode Clamped Multilevel Inverter, generally known as Neutral-Point-Clamped (NPC) Inverter, has an inherent problem causing Neutral Point (NP) potential variation. Until now, in many literatures NP potential problem has been investigated and lots of solutions have also been proposed. However, under fault and fault tolerant control, distinctive feature for NP potential variation problem was rarely published from the standpoint of reliability. In this paper, NP potential is analytically investigated both normal and faulty conditions under carrier based PWM. Subsequently, relation between fault detection time and size of capacitor is analyzed. This information is explored by simulation and experiment results, which contribute to enhance the reliability of inverter system.

• Journal of Power Electronics
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• v.18 no.3
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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.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.96-101
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• 2008

The magnesium oxide (MgO) protective layer plays an important role in plasma display panels (PDPs). Our previous work demonstrated that the properties of MgO thin film could be improved, which were deposited by Ion-Beam-Assisted Deposition (IBAD). However arc discharge always occurs during the IBAD process. To avoid this problem, Oxygen-Neutral-Beam-Assisted Deposition (NBAD) is used to deposit MgO thin films in this paper. The energy of the oxygen neutral beam was used as the parameter to control the deposition. The experimental results showed that the oxygen neutral beam energy was effective in determining in structural and discharge characteristics. The lowest firing inception voltage, the highest brightness and the highest luminous efficiency were obtained when the MgO thin film was deposited with an oxygen neutral beam energy of 300eV. The surface morphology of MgO thin film was also analyzed using AFM (Atomic Force Microscopy) and SEM (Scanning Electron Microscopy).

• Korea-Australia Rheology Journal
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• v.19 no.2
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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.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.17-24
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• 1989

Effects of cooking and drying methods on the lipids content and neutral lipid component of shrimp, Metapenaeus joyneri, were investigated. Total lipid content of the fresh shrimp was 6.0%(dry basis), which was not changed significantly depending on the cooking and drying methods. Lipid of the fresh shrimp was composed of 36.8% of neutral lipids, 21.5% of glycolipids, and 41.7% of phospholipids. Freeze dried shrimp was substantially higher in neutral lipid contents but lower in glycolipid and phospholipid contents than hot air dried one. Main components of the neutral lipids were triglycerides, free sterols, free fatty acids and esterified sterols. Freeze dried shrimp contained higher triglycerides contents than hot air dried shrimp, whereas free fatty acids content in hot air dried shrimp was greater than that of freeze dried one due to the decomposition of triglycerides to free fatty acids during hot air drying. Major fatty acid composition of the total lipid were palmitoleic acid, eicosapentaenoic acid and docosahexaenoic acid, and that of neutral lipid were palmitic acid, palmitic acid, oleic acid, eicosapentaenoic acid and docosahexaenoic acid in fresh shrimp.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.2
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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.

• The Research Journal of the Costume Culture
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• v.18 no.5
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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.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.207-211
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• 1996

This study was carried out to determine the lipid content and neutral lipid compositions of Japonica and indica rice bran oils. The average content ratio of neutral lipids, g]ycolipids and phospholipids were 89.5 : 4.0 : 6.5 in japonica rice bran oil and 93.7 : 2.6 : 3.7 in Indica rice bran oils, respectively. It was seen that the neutral lipid content was significantly higher in JAponica rice bran oil, while the contents of glycolopods and phospholipids were significantly higher in japonica rice bran oils. The neutral lipids consisted of esterified sterol, triglyceride, free fatty acid, free sterol, diglyceride and monoglyceride. Triglyceride was the highest (48.7-49.7%) among the neutral lipids. Major fatty acids of rice bran oils were oleic (39.65-43.68f)), linoleic (32.62-39.42%) and palmitic acid (16.54-18.83%). The linoleic acid content was higher in Japonica rice bran oils than in indica rice bran oils.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.1
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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.

• Korean Journal of Food Science and Technology
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• v.13 no.1
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• pp.30-36
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• 1981

Neutral lipids of the total lipid extracted from 4 representative varieties of barley grown in Korea and their corresponding malt were studied. Total lipids of barley and malt were solvent extracted with chloroform:methanol:water (1.0 : 1.0 : 0.9, v/v), The total lipids were fractionated into neutral and polar lipids by silicic acid column chromatography, and neutral lipids fraction was separated by thin layer chromatography and quantitated by TLC scanner. The fatty acid compositions was determined by gas liquid chromatography. The average content of total lipid in the 4 barleys and their malts were 3.3 and 2.9%, and average of neutral lipids content in the barley and malt lipids were 73.8 and 68.5%, respectively. Among the neutral lipids, triglycerides and free fatty acids were the major components, and triglycerides content decreased and free fatty acids content increased during malting. Sterol esters, free sterols, 1,3-and 1,2-diglycerides were the minor components of the neutral lipids, and contents of those components showed increasing tendency during malting. The major fatty acid composition of the total lipids were linoleic, palmitic and oleic acids, and in general, the malts had lower amounts of unsautrated fatty acids and high amounts of saturated fatty acids. Fatty acid composition of neutral lipids was of almost the same pattern as that of the total lipids.