Enumerating typical abelian prime-fold coverings of a circulant graph

Feng, R.,Kwak, J.H.,Kwon, Y.S. North-Holland Pub. Co ; Elsevier Science Ltd 2009 Discrete mathematics Vol.309 No.8

Enumerating the isomorphism classes of several types of graph coverings is one of the central research topics in enumerative topological graph theory (see [R. Feng, J.H. Kwak, J. Kim, J. Lee, Isomorphism classes of concrete graph coverings, SIAM J. Discrete Math. 11 (1998) 265-272; R. Feng, J.H. Kwak, Typical circulant double coverings of a circulant graph, Discrete Math. 277 (2004) 73-85; R. Feng, J.H. Kwak, Y.S. Kwon, Enumerating typical circulant covering projections onto a circulant graph, SIAM J. Discrete Math. 19 (2005) 196-207; SIAM J. Discrete Math. 21 (2007) 548-550 (erratum); M. Hofmeister, Graph covering projections arising from finite vector spaces over finite fields, Discrete Math. 143 (1995) 87-97; M. Hofmeister, Enumeration of concrete regular covering projections, SIAM J. Discrete Math. 8 (1995) 51-61; M. Hofmeister, A note on counting connected graph covering projections, SIAM J. Discrete Math. 11 (1998) 286-292; J.H. Kwak, J. Chun, J. Lee, Enumeration of regular graph coverings having finite abelian covering transformation groups, SIAM J. Discrete Math. 11 (1998) 273-285; J.H. Kwak, J. Lee, Isomorphism classes of graph bundles, Canad. J. Math. XLII (1990) 747-761]). A covering is called abelian (or circulant, respectively) if its covering graph is a Cayley graph on an abelian (or a cyclic, respectively) group. A covering p from a Cayley graph Cay(A,X) onto another Cay (Q,Y) is called typical if the map p:A->Q on the vertex sets is a group epimorphism. Recently, the isomorphism classes of connected typical circulant r-fold coverings of a circulant graph are enumerated in [R. Feng, J.H. Kwak, Typical circulant double coverings of a circulant graph, Discrete Math. 277 (2004) 73-85] for r=2 and in [R. Feng, J.H. Kwak, Y.S. Kwon, Enumerating typical circulant covering projections onto a circulant graph, SIAM J. Discrete Math. 19 (2005) 196-207; SIAM J. Discrete Math. 21 (2007) 548-550 (erratum)] for any r. As a continuation of these works, we enumerate in this paper the isomorphism classes of typical abelian prime-fold coverings of a circulant graph.

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>

노인의 성생활 만족도와 우울 간의 관계 연구

곽지은,김슬기,김지혜,이소현,이수진,이혜지,한솔 이화여자대학교 간호과학대학 2012 이화간호학회지 Vol.- No.46

Purpose: The purpose of this study was to know relationship between Sex Life Satisfaction and Depression of the Elderly, provide fundamental information of a sex related nursing intervention health promotion program in order to decrease depression and improve the quality of life for the elderly. Method: The subjects were collected by convenient sampling comprised of 113 elderly. The instruments used for this study were the Hwang’s sex life satisfaction measuring instrument to evaluate sex life satisfaction, the K-GDS(Korean Form of Geriatric Depression Scale) to evaluate depression. Result: The general factors effecting the sex life satisfaction of the elderly were as follows: Religion, Subjective financial condition. The general factors effecting depression were as follows: Personal relationship. Among the characteristics of the sexually active subjects’ sex lives, ‘How often do you enjoy your sexual life’ affected depression. As a result of analyzing Pearson’s product moment correlation coefficient in order to figure out the elderly’s perception of the relationship between the level of depression and sex life satisfaction, it showed that there was a statistically significant inverse relationship(p-value of 0.01). Conclusion: This study revealed that the relationship between Sex Life Satisfaction and Depression of Elderly were inversely related with statistical significance. Especially, the all-round quality of life that the elderly subjectively feel was an important factor affecting their sex life satisfaction and depression. Therefore, there should be an institutional improvement for advancement of the level of economic status and health, and a development or practice of program for personal relationships.

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.

대학생의 암 예방 수칙에 대한 인식 및 실천행태 연구

곽지연,김서연,김자영,이혜연,정문정,진수현,천선우,하소현,한희진,양숙자,김지연 이화여자대학교 간호과학대학 2016 이화간호학회지 Vol.- No.50

Purpose: The purpose of this study was to identify college student's perception and practice of 'National Cancer Prevention Actions' and the factors that influence the perception and practice. Method: The participants were 310 undergraduates selected by convenience sampling at colleges in Seoul. Instrument was 2014 Survey of Perception and Practice of National Cancer Prevention Actions by National Cancer Center(2014), and has been modified for the purpose of the study. The data were analyzed by t-test, ANOVA and Scheffe test with SPSS 23.0 Windows software. Results: The most recognized action for cancer prevention in college students was "Do not smoke, also avoid smoking smoke"(96.8%) while the most unrecognized was "Get a type B hepatitis vaccination"(58.7%). The most practiced action for cancer prevention in college students was "Sexually as to safe sex"(94.8%) while the most unpracticed was "Exercise five times a week or more, for at least 30 minutes a day"(33.9%). Among general characteristics, participants' age (t=-2.015, p<.05), major (F=3.109, p<.001), and residential type (F=4.959, p<.01) were statistically significant in the recognition of Cancer Prevention Actions and major(F=3.341 p<.05) and residential type(F=3.827, p<.05) were also significant in the practice of Cancer Prevention Actions. Among health characteristics, health concern(F=3.154, p<.05) and education in cancer(t=-3.112, p<.01) showed statistically significant differences in the recognition of Cancer Prevention Actions while health concern(F=7.896 p<.001) and subjective health status(F=9.913, p<.001) showed differences in the practice of Cancer Prevention Actions. Conclusion: These findings showed the gap between the perception and practice of cancer prevention actions. Considering the importance of individual characteristics, it is essential to develop a differentiated cancer prevention education program for college students. Also, nursing intervention program should be developed to raise the alertness of cancer in order to enhance cancer preventive practice.

Electric Probe Measurements at Edge Region During H‐Mode Discharges in KSTAR

Bak, J.G.,Oh, Y.S.,Kim, H.S.,Hahn, S.H.,Yoon, S.W.,Jeon, Y.M.,Xiao, W.W.,Ko, W.H.,Kim, W.C.,Kwak, J.G.,Woo, H.J.,Chung, K.S.,the KSTAR project team, WILEY‐VCH Verlag 2013 Contributions to plasma physics Vol.53 No.1

<P><B>Abstract</B></P><P>Electrical probe measurements are carried out at the scrape‐off‐layer (SOL) and divertor regions in order to investigate the characteristics of edge plasmas during H‐mode discharges in the Korea Superconducting Tokamak Advanced Research (KSTAR) device. Radial profiles of plasma parameters such as electron temperature T<SUB><I>e</I></SUB>, plasma density n<SUB><I>e</I></SUB>, and parallel flow velocity v<I><SUB>‖</SUB></I> are measured by using a fast reciprocating Langmuir probe assembly (FRLPA) at the SOL region. From the FRLPA measurements, it is found that the decay length of temperature λ<I><SUB>Te</SUB></I> and that of density λ<I><SUB>ne</SUB></I> are 2 <I>∼</I> 4 cm and 1 <I>∼</I> 3 cm, respectively. The magnitude of v<I><SUB>‖</SUB></I> near the last closed flux surface (LCFS) is 4 <I>∼</I> 15 km/s. The radial flux due to edge turbulence at the SOL region is investigated by using spectra analysis on electrostatic fluctuation levels such as ion saturation current Ĩ<I><SUB>is</SUB></I> and floating potential <TEX>$ \tilde{\rm V}_f$</TEX> obtained from the FRLPA measurement. The value of the flux is estimated as <I>∼</I> 10<SUP>20</SUP> particle m<SUP>−2</SUP> s <SUP>−1</SUP> near the LCFS. The poloidal distribution of the ion saturation current density j<I><SUB>is</SUB></I> is measured by fixed edge Langmuir probe array (ELPA) at the divertor region, and it is found that the positions of strike points from the ELPA measurement agree well with those reconstructed from the EFIT result using magnetic diagnostic data. From the spectrum analysis on the ELPA measurements at the divertor region during edge localized modes (ELMs) control in the H‐mode discharges, it is observed that the magnitude of <TEX>$ \tilde{\rm j}_{is}$</TEX>(<I>ω</I>) near strike point decreases when the ELMs are suppressed or mitigated (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)</P>

The degree complexity of smooth surfaces of codimension 2

Ahn, J.,Kwak, S.,Song, Y. Academic Press 2012 Journal of symbolic computation Vol.47 No.5

For a given term order, the degree complexity of a projective scheme is defined by the maximal degree of the reduced Grobner basis of its defining saturated ideal in generic coordinates (Bayer and Mumford, 1993). It is well known that the degree complexity with respect to the graded reverse lexicographic order is equal to the Castelnuovo-Mumford regularity (Bayer and Stillman, 1987). However, much less is known if one uses the graded lexicographic order (Ahn, 2008; Conca and Sidman, 2005). In this paper, we study the degree complexity of a smooth irreducible surface in P<SUP>4</SUP> with respect to the graded lexicographic order and its geometric meaning. As in the case of a smooth curve (Ahn, 2008), we expect that this complexity is closely related to the invariants of the double curve of a surface under a generic projection. As results, we prove that except in a few cases, the degree complexity of a smooth surface S of degree d with h<SUP>0</SUP>(I<SUB>S</SUB>(2))<>0 in P<SUP>4</SUP> is given by 2+(degY<SUB>1</SUB>(S)-12)-g(Y<SUB>1</SUB>(S)), where Y<SUB>1</SUB>(S) is a double curve of degree (d-12)-g(S@?H) under a generic projection of S. In particular, this complexity is actually obtained at the monomial x<SUB>0</SUB>x<SUB>1</SUB>x<SUB>3</SUB><SUP>(degY<SUB>1</SUB>(S)-12)-g(Y<SUB>1</SUB>(S))</SUP> where k[x<SUB>0</SUB>,x<SUB>1</SUB>,x<SUB>2</SUB>,x<SUB>3</SUB>,x<SUB>4</SUB>] is a polynomial ring defining P<SUP>4</SUP>. Exceptional cases are a rational normal scroll, a complete intersection surface of (2,2)-type, or a Castelnuovo surface of degree 5 in P<SUP>4</SUP> whose degree complexities are in fact equal to their degrees. This complexity can also be expressed in terms of degrees of defining equations of I<SUB>S</SUB> in the same manner as the result of A. Conca and J. Sidman (Conca and Sidman, 2005). We also provide some illuminating examples of our results via calculations done withMacaulay 2 (Grayson and Stillman, 1997).

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>

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.

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>