Optimal Stator Design of Interior Permanent Magnet Motor to Reduce Torque Ripple Using the Level Set Method

Kwack, Jeonghu,Min, Seungjae,Hong, Jung-Pyo IEEE 2010 IEEE transactions on magnetics Vol.46 No.6

<P> Interior permanent magnet (IPM) motor is widely used for many industrial applications and has relatively high torque ripple generated by reluctance torque which results in noise and vibration. Since the configuration of the stator has great influence on reluctance torque, design optimization is necessary to improve the torque performance of IPM motor. In this paper, structural optimization based on the level set method is formulated to reduce torque ripples by minimizing the difference between torque values at defined rotor positions and the constant target average torque value under the constrained material usage. The nonlinear ferromagnetic material boundary of the stator is implicitly represented through an embedded level set function and the movement of the material boundary is driven by the normal velocity derived from optimality and convergence conditions of the level set equation. The proposed method is applied to design the optimal stator configurations of a traction motor of hybrid electric vehicle and presents the improved torque characteristics of IPM motor. </P>

Application of DNDC Model to Estimate $N_2O$ Emissions from Green Tea Fields in Japan

Kwack, Yurina,Kobayashi, Kazuhiko 한국작물학회 2011 Journal of crop science and biotechnology Vol.14 No.2

Heavy doses of N fertilizers are commonly applied to green tea fields in Japan, and cause large amount of nitrate leaching in ground water and emission of ammonia and nitrous oxide ($N_2O$) to the atmosphere. The Denitrification and Decomposition (DNDC) model was tested against experimental data on $N_2O$ emissions from the tea field in Nishio, Aichi, Japan. There were reasonable agreements between the simulated and measured values of $N_2O$ emissions for this site. The model was then applied for estimating the environmental impacts as affected by farm management practices, climate change, and soil properties. The model results were assessed with respect to major indicators of agro-ecosystems including crop yield, soil organic carbon sequestration, nitrate leaching loss, and $N_2O$ emission. The results indicated that use of compost significantly reduced nitrate leaching and $N_2O$ emissions in comparison with N fertilizer. When soil pH and texture shifted to non-acidic and coarser soil, $N_2O$ emission increased; and a change in temperature and precipitation affected $N_2O$ emission, nitrate leaching, and SOC sequestration. This study thus revealed the biogeochemistry model as a powerful tool in addressing the complex efficacy of the alternative farm management practices in tea fields across various climate and soil conditions.

Screen-printed Source and Drain Electrodes for Inkjet-processed Zinc-tin-oxide Thin-film Transistor

Kwack, Young-Jin,Choi, Woon-Seop The Korean Institute of Electrical and Electronic 2011 Transactions on Electrical and Electronic Material Vol.12 No.6

Screen-printed source and drain electrodes were used for a spin-coated and inkjet-processed zinc-tin oxide (ZTO) TFTs for the first time. Source and drain were silver nanoparticles. Channel length was patterned using screen printing technology. Different silver nanoinks and process parameters were tested to find optimal source and drain contacts Relatively good electrical properties of a screen-printed inkjet-processed oxide TFT were obtained as follows; a mobility of 1.20 $cm^2$/Vs, an on-off current ratio of $10^6$, a Vth of 5.4 V and a subthreshold swing of 1.5 V/dec.

'Redvita': A Yellow-fleshed Kiwifruit with Red Color Around the Core

Kwack, Yong-Bum,Kim, Hong-Lim,Lee, Jae-Han,Chung, Kyeong-Ho,Chae, Won Byoung Korean Society of Horticultural Science 2017 원예과학기술지 Vol.35 No.3

Kiwifruits introduced to Korea typically have green fruit flesh, yellow flesh, or yellow flesh with red coloration around the core. Here, we describe a new cultivar called 'Redvita', the first kiwifruit cultivar of Korea with yellow flesh and red coloration around the core. A conventional field cross was conducted in 2003, and permission for the final release of 'Redvita' was obtained in 2012. 'Redvita' originates from 'Red Princess', a maternal vine known for the red coloration in its flesh. The pollinizer is 'NHK0013' (IT233175), which blooms in early May. A principal feature of 'Redvita' is its high vitamin C content, which at an average of 140 mg per 100 g of fresh weight is 2 - 4 times higher than other commercial cultivars. The average fruit weight is 97 g; bigger than that of the control cultivar 'Hongyang'. 'Redvita' blooms in mid-May and is usually harvested in early to mid-October, approximately 150 - 160 days after anthesis. 'Redvita' produces 3 or 4 flowers per fruiting shoot, with no small lateral flowers, therefore does not need to be thinned before blooming for commercial production. The cultivar is acidulous because of a high titratable acidity content (about 1.5%), which is higher than other cultivars (less than 1.0%). 'Redvita' was registered with the Korean Seed and Variety Service in 2015 for plant variety protection rights (no. 5604).

Verifications of Resistance to Phytophthora spp. in 2-year-old Citrus junos Cultivars and Related Specie

Kwack, Yong-Bum,Kim, Hong Lim,Kwak, Youn-Sig,Lee, Yong Bok Korean Society of Soil Science and Fertilizer 2018 한국토양비료학회지 Vol.51 No.1

Yuzu (Citrus junos) gummosis disease, caused by Phytophthora nicotianae, was first reported in 1997. As known in citrus, Phytophthora is the most fastidious soil-borne pathogen to control. In order to minimize its damage to Citrus spp., integrated pest management (IPM) approach, including fungicide chemicals and resistant cultivars, is necessary. Therefore, in this study we tried to evaluate tolerance of yuzu cultivars and its related species against yuzu Phytophthora. Trifoliate orange was evaluated as a susceptible host to yuzu Phytophthora by both mycelial growth onto extract media and immature fruit inoculation. However, in zoospores spray-inoculation on 2-year-old cuttings tree, trifoliate orange appeared to have a resistant property as showing less than 6% diseased leaf rate. Among yuzu cultivars only 'Namhae No. 1' appeared resistant property against both P. nicotianae and P. citrophthora. The 'Namhae No. 1' showed 5.7% and 10.6% diseased leaf ratio by P. nicotianae and P. citrophthora, respectively. Clearly, in order to reduce damages caused by two yuzu Phytophthora, we suggest that growers may utilize a trifoliate orange as a rootstock and 'Namhae No. 1' as a scion for fruit production.

The Unique, Minimum Variance, Linear, Unbiased Stepwise Estimator

Kwack,Sung-Yeung 서울大學校 商科大學 韓國經濟硏究所 1966 經濟論集 Vol.5 No.2

Arthur Goldberger and others have discussed the degree of the bias of the stepwise estimators of the parameters in a multiple linear regression model Y=X_1β_1+X_2β_2+ε. The present paper attempts to develop a stepwise method for estimating the parameters, by which the unique, minimum variance, linear, unbiased estimators can be obtained, even if the orthogonality of X_1 to X_2 is not assumed.

Comparison of the Short Term Toxicity of Phthalate Diesters and Monoesters in Sprague-Dawley Male Rats

Kwack, Seung-Jun,Han, Eun-Young,Park, Jae-Seok,Bae, Jung-Yun,Ahn, Il-Young,Lim, Seong-Kwang,Kim, Dong-Hyun,Jang, Dong-Eun,Choi, Lan,Lim, Hyun-Jung,Kim, Tae-Hyung,Patra, Nabanita,Park, Kui-Lea,Kim, Hyu Korean Society of ToxicologyKorea Environmental Mu 2010 Toxicological Research Vol.27 No.1

This study was carried out to investigate the short term toxicity of nine phthalate diesters including di-2(ethylhexyl) phthalate (DEHP), di(n-butyl) phthalate (DBP), di-n-octyl phthalate (DnOP), diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dimethyl phthalate (DMP), di-isodecyl phthalate (DIDP), diundecyl phthalate (DUP), and di-isononyl phthalate (DINP) and five phthalate monoesters including mono- (2-ethylhexyl) phthalate (MEHP), monobutyl phthalate (MBuP), monobenzyl phthalate (MBeP), monoethyl phthalate (MEP), monomethyl phthalate (MMP) and phthalic acid (PA) in Sprague-Dawley male rats. Animals were administered 250 mg/kg/day (monoesters and PA) or 500 mg/kg/day (diesters) of phthalate for two weeks. All animals were examined for body and organ weights, blood hematology, serum biochemistry, and urine analysis. The body weight gain was significantly lower in rats treated with BBP, DBP, DINP, MEHP, MBuP, and PA than that of control. Liver weights were significantly increased in the DEHP, DBP, DnOP, DIDP, and MEHP groups as compared to the control group. Testes weights were significantly decreased only in the DEHP-, DnOP-, and DIDP-treated groups as compared to the control. Significant differences in hematological changes were not observed in any treatment groups. Significant increases in blood glucose levels were observed in the DEHP, MEHP, and MBeP groups. Aspartate aminotransferase (AST) levels were significantly increased in the DBP, DUP, DINP, MBuP, and MBeP groups, whereas alanine aminotransferase (ALT) levels were significantly increased only in the DEHP and MEHP groups. Serum ALP levels were significantly higher in phthalate diester (500 mg/kg/day)-treated rats as compared to control. However, the total cholesterol level was significantly reduced in the DEHP- and DIDP-treated groups, whereas serum triglyceride (TG) levels were higher in the DINP-, MEHP-, and MBuP-treated groups. These results suggest that short term toxicity of phthalate monoesters produces adverse effects as similar to phthalate diesters in Sprague-Dawley rats.

Syllable Structure and Cyclic Domain

Kwack,Dong-gee 新羅大學校 1985 論文集 Vol.19 No.-

음절의 구조가 음절경계와 분절음으로 이루어진 선형적인 구성이기 보다는 내적구조를 가진 위계적인 구성이라고 가정할 때 그 음절구조는 음운현상에 관한 보다 많은 규칙성을 제시해준다. 이와 같은 음절의 위계적 구조에 관해서는 여러가지 견해가 있다. 그러나 본 논문에서는 대표적인 두가지만 논한다. 이 중 첫 번째 견해는 음절구조가 통사론의 귀절구성과 같은 직접 성분구조를 갖는다는 것이다. 이 성분들은 頭音(onst), 核音(nucleus), 脚音(coda)으로 구성되어 있고 다시 核音과脚音은 합하여 韻母(rhyme)를 형성한다. 頭音성분에 관해서는 여러 언어에 보편적으로 존재하는 頭音규약(onset principle)이 있으나 脚音성분에 대해서는 이런 규약 같은 것이 없기 때문에 음절의 성분요소로써 이 脚音을 설정할 필요가 없는 것 같다. 따라서 脚音성분의 당위성이 없다면 核音성분의 당위성도 문제시된다. 그러므로 韻母성분을 核音성분과 脚音성분으로 나눌 이유가 없기 때문에 본 논문에서는 음절의 구성성분으로 頭音성분과 韻母성분만 인정하여 음운현상을 설명하는 데 사용한다. 또한 여기서 문제되는 것은 각 성분밑에 분절음들이 二元分枝에 따라 배치되는 것이냐는 것인데 본 논문에서는 多元分枝도 가능하다는 사실을 제시한다. 다음 두 번째 견해로는 상위음절층위와 분절음층위 사이에 중간 층위 즉 CV층위를 인정하여야 한다는 것인데 이것은 Clements and Keyser가 주장하는 바다. 그러나 Yip는 CV층위 대신에 X층위를 설정하여야 한다고 또한 주장한다. Harris가 기술한 스페인語의 음운현상이나 한국어 음운현상에 있어서는 이런 층위를 설정할 필요가 없다는 증거가 있기에 본 논문에서는 첫 번째의 견해인 성분구조방식을 따른다. 분절음들이 성분구조에 따라 음절화를 이루면 여기 음절정보를 필요로 하는 음운규칙이 적용된다. 이 음운규칙과 음절화는 규칙상호간에 급여관계와 출혈관계를 맺는다. 이들은 또한 어휘규칙과 未어휘규칙으로 나누어지고 어휘규칙들은 순환영역에 있어서 적용의 제한을 받는다. 순환영역에는 명사, 동사, 형용사와 같은 어휘범주가 들어간다. Harris는 굴절어미를 어휘범주와 다른 순환영역에 두었기 때문에 규칙상호간의 순서가 엄밀하게 필요했지만 본 논문에서는 스페인語와 한국어의 분석을 통해 이런 굴절어미를 어간에 귀속시켜 동일한 순환영역속에서 처리함으로써 Harris가 규정했던 여러 규칙상호간의 문제점을 없앴다. 즉 굴절어미가 동일순환영역속에 있다고 가정할 때 음절구조 할당규칙, 음절구조 재할당규칙, 어휘규칙, 그리고 재음절화규칙 상호간에는 자연적으로 적용순서가 주어져 올바른 도출형이 유도될 수 있는 것이다.

The No-Observed-Adverse-Effect Level (NOAEL) of Baby Aloe Powder (BAP) for Nutraceutical Application Based Upon Toxicological Evaluation

Kwack, Seung Jun,Do, Seon-Gil,Kim, Young Woo,Kim, Yeon-Joo,Gwak, Hyo-Min,Park, Hyun Jong,Roh, Taehyun,Shin, Min Kyung,Lim, Seong Kwang,Kim, Hyung Sik,Lee, Byung-μ Taylor Francis 2014 Journal of toxicology and environmental health. Pa Vol.77 No.22

Carbohydrate reserves of non-fruiting young kiwifruit vines as affected by early artificial defoliation

Kwack, Y. B.,Kim, H. L.,Chae, W. B.,Kim, S. H.,Lee, Y. B.,Kim, J. G. Springer Science + Business Media 2014 Horticulture, Environment, and Biotechnology Vol.55 No.6