Progress in the development of heating systems towards long pulse operation for KSTAR

Kwak, J.G.,Bae, Y.D.,Chang, D.H.,Chang, D.S.,Hong, B.G.,Hwang, C.K.,In, S.R.,Jeong, S.H.,Jin, J.T.,Jung, K.S.,Kim, B.R.,Kim, J.,Kim, S.K.,Kim, T.S.,Lee, D.W.,Lee, K.W.,Oh, B.H.,Seo, C.S.,Seo, M.S.,Yoo International Atomic Energy Agency 2007 Nuclear fusion Vol.47 No.5

<P>Construction of the Korea superconducting tokamak advanced research (KSTAR) tokamak is in its final phase. For the long-pulse KSTAR discharges, the ion cyclotron range of frequencies (ICRF) and neutral beam injection (NBI) heating systems are expected to play important roles through a selective heating of ions and electrons, control of the plasma pressure and current profiles, a core fuelling and beam diagnostics for the KSTAR. In addition, the ICRF system is expected to be used for possible discharge cleaning and assisting in the tokamak startup. In this paper, the recent progress in the development of the ICRF and the NBI heating systems is described. The four-strap ICRF antenna has been successfully tested for a voltage up to 41 kV for a pulse length of 300 s (to 46 kV for 20 s) in a test chamber. A prototype KSTAR NBI system has been developed. At present, the system has successfully produced a 1 MW beam power for 200 s and a 3.5 MW output beam power for 4 s.</P>

Production of (S)-3-hydroxybutyrate by metabolically engineered Saccharomyces cerevisiae

Yun, E.J.,Kwak, S.,Kim, S.R.,Park, Y.C.,Jin, Y.S.,Kim, K.H. Elsevier Science Publishers 2015 Journal of biotechnology Vol.209 No.-

(S)-3-Hydroxybutyrate (S-3HB) can be used as a precursor for the synthesis of biodegradable polymers such as polyhydroxyalkanoate and stereo-specific fine chemicals such as antibiotics, pheromones, and drugs. For the production of S-3HB in yeast, the biosynthetic pathway of S-3HB from acetyl-CoA, consisting of the three enzymes, acetyl-CoA C-acetyltransferase (ACCT), acetoacetyl-CoA reductase (ACR), and 3-hydroxybutyryl-CoA thioesterase (HBT), was introduced into Saccharomyces cerevisiae. An engineered yeast strain overexpressing ERG10, hbd, and tesB genes not only exhibited enzyme activities of AACT, ACR, and HBT, but also produced S-3HB from ethanol. In order to increase the titer of S-3HB, a fed-batch fermentation based on pulse feeding of ethanol as a carbon source was performed, and a final S-3HB titer of 12.0g/L was achieved. This is the first report on the production of 3HB by engineered yeast, utilizing ethanol as the carbon source, suggesting that the industrially preferred S. cerevisiae can be a promising host for producing S-3HB.

Key Features in the Operation of KSTAR

Jong-Gu Kwak,Oh, Y. K.,Kim, K. P.,Kim, S. W.,Hong, S. H.,Chu, Y.,Lee, H. J.,Kim, Y. O.,Kim, J.,Park, S. L.,Hahn, S. H.,Park, M. K.,Kim, H. K.,Bak, J. G.,Bae, Y. S.,Ko, W. H.,Lee, S. G.,Lee, J. H.,Jung IEEE 2012 IEEE transactions on plasma science Vol.40 No.3

<P>The Korea Superconducting Tokamak Advanced Research (KSTAR) device is aimed at advanced tokamak (AT) research. Three years have passed since it achieved its first plasma in 2008. Because it is a superconducting machine and is working toward AT research, it has unique features in terms of the machine engineering and operation. The toroidal field (TF) magnet coils are made of Nb<SUB>3</SUB>Sn, which provide high TFs up to 3.5 T, and have been fully tested. The poloidal field (PF) magnet coils, consisting of both Nb<SUB>3</SUB>Sn and NbTi, which have a maximum current of 25 kA in their design, were tested up to 15 kA. A thermal hydraulic analysis is being conducted for PF magnet coil operation. All plasma-facing components (PFCs) are equipped with water cooled graphite tiles and have the capability of being baked up to 350°C. A startup scenario, which considered both the effect of the ferromagnetic material in the cable in conduit conductor jacket of the magnet coils as well as a nonferromagnetic up-down asymmetry in the cryostat structure, was developed and demonstrated its effectiveness by the last two year's reliable operations. Passive stabilizers and in-vessel control coils (IVCCs) are key components to realize AT operation in KSTAR. The segmented IVCC coils were connected to form circular coils for internal vertical control in 2010, and diverted plasmas with high elongation (κ~1.8, δ>;0.6) were achieved. A neutral beam injection (NBI) system was developed aiming at 2 MW, 300 s per ion source which meets the long-pulse requirement of KSTAR. An NBI ion source with a power of 1.7 MW at 100 kV has been commissioned for 10 s. Finally, ELMy H-modes were successfully produced with 1.3-MW NBI power at a plasma current of 0.6 MA in the 2010 campaign. The first H-mode discharge (#4200) in KSTAR was achieved one year earlier than officially planned and was done at B<SUB>T</SUB> = 2 T with I<SUB>p</SUB> = 0.6 MA in a well-balanced double null configuration after boronization on the PFC. Successful operations in the early days of KSTAR including H-mode experiments revealed the capability of advanced and steady-state operation which is essential for the international thermonuclear experimental reactor (ITER) and future fusion reactors.</P>

Overview of KSTAR research progress and future plans toward ITER and K-DEMO

Park, H.K.,Choi, M.J.,Hong, S.H.,In, Y.,Jeon, Y.M.,Ko, J.S.,Ko, W.H.,Kwak, J.G.,Kwon, J.M.,Lee, J.,Lee, J.H.,Lee, W.,Nam, Y.B.,Oh, Y.K.,Park, B.H.,Park, J.K.,Park, Y.S.,Wang, S.J.,Yoo, M.,Yoon, S.W.,B IOP 2019 Nuclear fusion Vol.59 No.11

<P>A decade-long operation of the Korean Superconducting Tokamak Advanced Research (KSTAR) has contributed significantly to the operation of superconducting tokamak devices and the advancement of tokamak physics which will be beneficial for the ITER and K-DEMO programs. Even with limited heating capability, various conventional as well as new operating regimes have been explored and have achieved improved performance. As examples, a long pulse high-confinement mode operation with and without an edge-localized mode (ELM) crash was well over 70 and 30 s, respectively. The unique capabilities of KSTAR allowed it to improve the capability of controlling harmful instabilities, and they have been instrumental in uncovering much new physics. The highlights are that the L/H transition threshold power is sensitive to the resonant magnetic perturbation (RMP) and insensitive to non-resonant magnetic perturbation. Co-<I>I</I> <SUB>p</SUB> offset rotation dominated by an electron channel predicted by general neoclassical toroidal viscosity theory was confirmed. Improved heat dispersal in a divertor system using three rows of rotating RMP was demonstrated and predictive control of the ELM-crash with <I>a priori</I> modeling was successfully tested. In magnetohydrodynamic physics, validation of the full reconnection model (i.e. <I>q</I> <SUB>0</SUB>  >  1 right after the sawtooth crash) and self-consistent validation of the anisotropic distribution of turbulence amplitude and flow in the presence of the 2/1 island with theoretical models were achieved. The turbulence amplitude induced by RMP was linearly increased with the slow RMP coil current ramp-up time (i.e. the magnetic diffusion time scale). The <I>D</I> <SUB> <I>α</I> </SUB> spikes (i.e. ELM-crash amplitude) was linearly decreased with the turbulence amplitude and not correlated with the perpendicular electron flow. In the turbulence area, a non-diffusive ‘avalanche’ transport event and the role of a quiescent coherent mode in confinement were studied. To accommodate the anticipation of a higher performance of the KSTAR plasmas with the increased heating powers, a new divertor/internal interface with a full active cooling system will be implemented after a full test of the new heating (neutral beam injection II and electron cyclotron heating) and current drive (CD) (Helicon and lower hybrid CD) systems. An upgrade plan for the internal hardware, heating systems and efficient CD system may allow for a long pulse operation of higher performance plasmas at <I>β</I> <SUB>N</SUB>  >  3.0 with <I>f</I> <SUB>bs</SUB> ~ 0.5 and <I>T</I> <SUB>i</SUB>  >  10 keV.</P>

Monthly measured primary and new productivities in the Ulleung Basin as a biological "hot spot" in the East/Japan Sea

Kwak, J. H.,Lee, S. H.,Park, H. J.,Choy, E. J.,Jeong, H. D.,Kim, K. R.,Kang, C. K. Copernicus GmbH 2013 Biogeosciences Vol.10 No.7

<P><p><strong>Abstract.</strong> The Ulleung Basin (UB), located in the southwestern part of the East/Japan Sea (EJS), is considered having an unusually high productivity for a deep basin. Recently changes have been reported in physical, chemical, and biological properties. Here we measured the primary and new productivities in the UB using a ¹³C-¹⁵N dual isotope tracer technique. Measurements took place every month for the first time throughout a year for a better estimate of the annual primary production in the EJS. Temporal variations of temperature, salinity, and density (&amp;sigma;_<i>t</i>) in the study area were highly seasonal as expected for an ocean in the temperate zone. Nutrient distributions reflected these seasonal fluctuations in the vertical structure of the water column. Diatoms were in general the most dominant phytoplankton ranging from 15.5 to 82.2% with an average of 42.0% (S.D. = ±9.9%). Based on those average daily productivities from our monthly measurements, the annual primary, new, and regenerated production in the UB were 273.0 g C m⁻² yr⁻¹, 62.6 g N m⁻² yr⁻¹, and 48.7 g N m⁻² yr⁻¹, respectively. Our estimated high <i>f</i> ratio (0.59) in the UB, indicated that the predominant nitrogen source for primary production was nitrate. This is comparable with the nitrogen source in a productive coastal-upwelling region. New carbon production by phytoplankton is estimated as 145.6 g C m⁻² yr⁻¹ (S.D. = ±40.8 g C m⁻² yr^&amp;minus;1) which indicates that a large portion (53.9%) of the total annual primary production might potentially be exported from the diatom-dominated euphotic zone to a deeper zone in the UB. Further intense integrated field observations will be necessary to improve our understanding of the current marine ecosystem in the UB as an important biological production area in the EJS.</p> </P>

거주지역에 따른 유아의 기호도 조사

곽동경,이혜상,박신정,최은희,홍완수,장미라 대한영양사협회 1998 대한영양사협회 학술지 Vol.4 No.1

The purpose of this study was to evaluate the preference trend of children in the child-care centers in relation to certain environmental factors such as size of the residing town. This evaluation was conducted using questionnaire survey where the mother of each child was required to complete a preference questionnaire including 83 food items. Statistical data analysis was completed using SAS package program. The results of this survey showed the followings : 1. Generally, the preference level of the children living in large cities were higher than those of medium cities except in case of vegetables, while the preference level of the children living in large cities were higher than those of rural area except in case of hard-boiling(jorim) and vegetables. The subjects showed high preferences to bulgogi(4.53), pork-cutlet(4.52), fried chicken(4.51), jajangmyone(4.45), kimgui(4.43), roasted fish(4.31), kim-bab(4.17), roasted ham(4.13). 2. There was a tendency that a la carte, bread and noodles received higher preference scores. Items of Korean style soup attained higher preference scores than stew(ggigae). The preference scores of fried, broiled or pan-fried items(jun) were higher than those of other items such as seasoned vegetables(namool). 3. The preference scores of children (routinely or occasionally) skipping breakfast or supper were generally low. There was no significant difference according to the existence of mother's job except in case of steamed or pan-fried items, provided that the preference scores of the children whose mother had a job were slightly higher in general. Further, there was no significant difference according to the size of the monthly income of the household except stew, provided that the preference scores of the children whose household had lower income were slightly higher in general.

EFFECT OF RECOMBINANT BOVINE SOMATOTROPIN ON GROWTH PERFORMANCE AND CARCASS CHARACTERISTICS OF FINISHING KOREAN NATIVE BULLS

Kwak, B.O.,Ha, J.K.,Chang, B.S. Asian Australasian Association of Animal Productio 1996 Animal Bioscience Vol.9 No.1

This experiment was conducted to investigate the effect of bST administration on growth performance and carcass characteristics of finishing Korean native bulls. Fifty four Korean native bulls of about 14 months of age weighting an average 420 kg were assigned to receive no injection of bST, 250 mg of bST s.c. injection every week, or 500 mg bST s.c. injection every 2 weeks (Control, 250ST, 500ST) in a $3{\times}3$ randomized block design for a period of 20 weeks Animals administered with bST responded with decreased feed DMI by 8%(p < 0.01), increased ADG by 12%(p < 0.05), and increased gain/feed ratio by 20%(p < 0.01). But there was no significant difference in the growth performance between 250ST and 500ST. Administration of bST increased dressing percentage by 1.8%(p < 0.05), and tended to increase longissimus muscle area and decrease backfat thickness and marbling score.

W(110) 표면에 CO와 O_2의 공동흡착

이경희,한현석,윤효근,부진효,이순보,곽현태 성균관대학교 기초과학연구소 1998 論文集 Vol.49 No.-

The coadsorption of CO and O₂ on W(110) surface was studied by LEED, TDS, and photoelectron spectroscopy. In the TDS for the coadsorption of CO at RT on O₂ precovered W(110) surface, two CO desorption states were observed at about 400 and 1150 K, called α and β , respectively. The β-CO spectra with second order desorption kinetics were shifted to lower desorption temperature as increasing the amount of preadsorbed atomic oxygen on the W(110). Moreover, the β-CO spectra were gradually increased with increasing the amount of preadsorbed oxygen to 0.5 ML. Even though a (2 x 1) LEED pattern appeared during oxygen adsorption at RT and 1-3 L oxygen exposures, we didn't observe any new pattern induced by CO in this study. Only the structure of c(11 x 5) was obtained at temperature in the range of 800-1100 K. These results indicated that there were interaction between CO and O and thereby the β-CO might riot be dissociated even at the higher temperature than 800 K. By using the XPS and UPS, it was also confirmed that the coadsorbed β-CO at 900 K doesn't dissociate as the experimental results of the adsorption of pure CO on W(110) surface at the same temperature. According to the valence band spectra, two CO peaks at near -10.7 eV (4σ) and -7.0 eV (5σ+1π) were observed, indicating molecular CO adsorption on the oxygen preadsorbed surface at RT. Even heating the coadsorbed surface to 900 K, we could also detect the CO 4σ peak which can be an important factor for identifying a contribution of the CO 4σ molecular orbital to the CO-metal bond. To our best knowledge, this is the first report and quite contradictory result to that reported previously.

왜 韓國人에는 冠狀動脈硬化性心臟病이 적은가?

李圭澤,權五鉉,金庚植,南相哲,金東洛,金相煜,郭然植,金聖倍,韓龍燮,金源准 慶北大學校 1960 論文集 Vol.4 No.-

A relationship between the amount of dietary fat, the concentration of serum lipids and the development of coronary heart disease has been one of the most important medical problems in the recent years. Accumulated data indicate that striking differences exist among different populations in the incidence and severity of coronary heart disease and these differences tend to correlate with dietary factors rather than with racial or other factors. Extensive studies on healthy peoples in various parts of the world lead to the conclusion that the incidence of coronary heart disease is directly to related the average level of serum cholesterol and this cholesterol level is directly related to the percentage of calories provided by fats in the diet, particularly common saturated fats of meats and dairy products. Such a study has never been carried out in Korea and studies in other countries of the Far· East have indicated that their diets are extremely low in the fat content and their serum cholesterol and frequency of the coronary heart disease are also remarkably low. In an attempt to correlate the dietary fat intake, blood lipid level and the Incidence of coronary heart disease in Korean people, the following population groups are selected. 319 farmers, 100 Taegu City people, 50 upper class people, 129 Buddhist Monks, and 90 Korean soldiers attached to the United States Army who have been fed American diet for from 1 to 18 months and 60 American soldiers and officers. On all of those people an analysis of dietary constituents, complete blood lipid analysis including total and free cholesterol, cholesterol ester, total esterified fatty acid . lipid phosphorus, neutral fat. C/P ratio and cholesterol ester/total cholesterol ratio and 12 leads electrocardiogram for evidences of the coronary heart disease were performed and the data thus obtained were analyzed and correlated. The most striking difference in diets of various groups is the fat content. The fat intake of Buddhist Monks and farmers is significantly lower than any other groups and their serum lipid level and the incidence of abnormal electrocardiogram are also lowest in the whole groups. Among Koreans upper class people of Taegu city have the highest fat intake and also the highest serum lipid level and the incidence of abnormal electrocardiogram. The dietary fat intake of Korean is significantly lower than that of American and the serum lipid level and the incidence of coronary heart disease are also significantly lower than American. The results of current study indicate that there is direct correlation between the dietary fat intake, the serum lipid level and the incidence of coronary heart disease and it seems to be reasonable to conclude that among many factors which may affect the remarkably low incidence of the coronary heart disease in Koreans the low dietary fat intake is the most important factor.

플라스틱 기판에SiO₂ Capping layer와 엑시머 레이저 결정화로 제작된 극저운다결정실리콘 박막트랜지스터의 결정립 성장연구

정현석,최광남,곽서관,김동식,정관수 경희대학교 레이저공학연구소 2005 레이저공학 Vol.16 No.-