SEARCH FOR PULSED γ-RAY EMISSION FROM GLOBULAR CLUSTER M28

Wu, J. H. K.,Hui, C. Y.,Wu, E. M. H.,Kong, A. K. H.,Huang, R. H. H.,Tam, P. H. T.,Takata, J.,Cheng, K. S. IOP Publishing 2013 ASTROPHYSICAL JOURNAL LETTERS - Vol.765 No.2

<P>Using the data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, we have searched for gamma-ray pulsations from the direction of the globular cluster M28 (NGC 6626). We report the discovery of a signal with a frequency consistent with that of the energetic millisecond pulsar (MSP) PSR B1821-24 in M28. A weighted H-test test statistic of 28.8 is attained, which corresponds to a chance probability of similar to 10(-5) (4.3 sigma detection). With a phase-resolved analysis, the pulsed component is found to contribute similar to 25% of the total observed gamma-ray emission from the cluster. However, the unpulsed level provides a constraint for the underlying MSP population and the fundamental plane relations for the scenario of inverse Compton scattering. Follow-up timing observations in radio/X-ray are encouraged to further investigate this periodic signal candidate.</P>

남조류와 녹조류에서의 수소생산을 위한 배양 조건의 최적화

윤종현(J. H. Yoon),공경택(K. T. Kong),심상준(S. J. Sim),김미선(M.S. Kim),박태현(T. H. Park) 한국수소및신에너지학회 2002 한국수소 및 신에너지학회논문집 Vol.13 No.4

Blue-green algae and green algae have the unique characteristic of using CO₂ in the air as a carbon source and solar energy as an energy source and producing H₂ with water used as the primary electron donor. The cells take up CO₂ first to produce cellular substances, which are subsequently used for H₂ production. Since the optimal operating conditions for the CO₂ uptake and H₂ production are different, a two-stage system can be effectively employed to separate these two phases. For the efficient production of H₂ in the second stage, in this study, the culture condition of blue-green algae was optimized for the effective CO₂ uptake and cell growth in the first stage, and high cell density culture was carried out using repeated injections of CO₂. In green algae, the amount and patterns of organic compounds have a connection with growth stage or dark fermentation time. The hydrogen production was greatly influenced by dark fermentation time.

Comparative studies on steam gasification of ash-free coals and their original raw coals

Kong, Y.,Kim, J.,Chun, D.,Lee, S.,Rhim, Y.,Lim, J.,Choi, H.,Kim, S.,Yoo, J. Pergamon Press ; Elsevier Science Ltd 2014 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.39 No.17

Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. As a means to achieve repeated use of catalysts, four different ash-free coals (AFCs) containing less than 0.2 wt% ash are produced in this work. Steam gasification of ash-free coals (AFCs) and their parent raw coals of various ranks ranging from lignite (Eco) to coking coal (Posco) is performed in a fixed bed reactor at 700-900 <SUP>o</SUP>C. Regardless of the rank of the parent raw coals, all the AFCs behave like a highly carbonized coal such that their gasification rate are similarly slow and they exhibit relatively low H<SUB>2</SUB>/CO ratio. The steam gasification and associated CO to CO<SUB>2</SUB> conversion of the AFCs are, however, significantly enhanced by K<SUB>2</SUB>CO<SUB>3</SUB>, resulting in the higher H<SUB>2</SUB>/CO and CO<SUB>2</SUB>/CO molar ratio.

전신 골밀도와 기능 상실 치율 및 하악골 골소주 흡수 양상의 상관 관계

공선애,송용준,노재형,안종인,고영규,김종화,이희철 인제대학교 1996 仁濟醫學 Vol.17 No.1

1993년 3월부터 1995년 6월까지 부산백병원 치과에 내원한 40세 이상 65세 이하의 연령층에 속하는 여성 환자를 대상으로 임상 검사 및 방사선학적 검사를 시행한 결과 치주병에 이환된 치아의 비율이 20% 이하인 30명을 선정하여 이화학적 검사, 치아 파노라마 단층 촬영을 이용한 방사선학적 검사 및 LUNAR DPX 골밀도 측정기를 이용한 전신 골밀도 측정을 시행하였다. 이를 통한 검사 결과를 분석하면서 전신 골밀도 수준과 기능 상실치율 및 하악골 내 골소주의 흡수 양상 간의 상관 관계를 평가하여 다음과 같은 결과를 얻었다. 1.골대사의 지표인 칼슘, 무기인, 알칼리성 인산화효소를 측정하여 전신 골밀도와의 상관 관계를 검증하였으나 유의한 상관 관계는 없었다 (P>0.05). 2.전신 골밀도 분석 결과는 기능 상실치수 및 기능 상실치율에 유의한 상관 관계를 가지고 있었다 (연령에 의한 영향을 보정함)(P=0.0050). 3.30명 환자의 기능 상실치율은 평균 33.7%였으며 치아 파노라마 단층 촬영을 분석한 결과 이공 주변부의 골소주 흡수양상은 현저하여 Diffuse resorption type, Moth-eaten type, Limited(round) resorption type으로 분류 가능하였으나 각 군별로 전신 골밀도 분석 평균의 차이는 없었다(P>0.05). The author selected 30 women whose periodontal disease rate was no more than 20%. They were the patients who have visited at the Dept. of Dentistry in Paik hospital from 1993 to 1995. Biochemical examination, dental panoramic tomogram check and toal body bone density check were done using LUNAR DPX bone densitometer. The results were analysed by total body bone density level, function loss teeth rate and mandibular trabeculi resorption pattern. Then, the author accessed the correlation on the basis of their results. The following observations were made ; 1.Calcium, phosphorus and alkaline phosphatase levels were not correlated with tonal body bone density (P>0.05) 2.There was a good correlation between function loss teeth rate and total body bonedensi ty(corrected by age) (P = 0.0050) 3.We analysed dental panoramic tomograms of 30 women whose periodontal disease rate was no more than 20%. The mean function loss teeth rate in 30 patients was 33.7%. So we could divide mandibular trabeculi resorption pattern into 3-types ; Diffuse resorption type, Moth-eaten type, Limited (round) resorption type. But, there was no correlation between each resorption pattern and total body bonedensity (P>0.05).

Broad-band high-energy emissions of the redback millisecond pulsar PSR J2129-0429

Kong, Albert K H,Takata, Jumpei,Hui, C Y,Zhao, J,Li, K L,Tam, P H T Oxford University Press 2018 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.478 No.3

DISCOVERY OF AN ULTRACOMPACT GAMMA-RAY MILLISECOND PULSAR BINARY CANDIDATE

Kong, Albert K. H.,Jin, Ruolan,Yen, T.-C.,Hu, C.-P.,Hui, C. Y.,Tam, P. H. T.,Takata, J.,Lin, L. C. C.,Cheng, K. S.,Park, S. M.,Kim, C. L. IOP Publishing 2014 ASTROPHYSICAL JOURNAL LETTERS - Vol.794 No.2

<P>We report multi-wavelength observations of the unidentified Fermi object 2FGL J1653.6-0159. With the help of high-resolution X-ray observations, we have identified an X-ray and optical counterpart to 2FGL J1653.6-0159. The source exhibits a periodic modulation of 75 minutes in the optical and possibly also in the X-ray. We suggest that 2FGL J1653.6-0159 is a compact binary system with an orbital period of 75 minutes. Combining the gamma-ray and X-ray properties, 2FGL J1653.6-0159 is potentially a black-widow-/redback-type gamma-ray millisecond pulsar (MSP). The optical and X-ray light curve profiles show that the companion is mildly heated by the high-energy emission and that the X-rays are from intrabinary shock. Although no radio pulsation has yet been detected, we estimated that the spin period of the MSP is similar to 2 ms based on a theoretical model. If pulsation can be confirmed in the future, 2FGL J1653.6-0159 will become the first ultracompact rotation-powered MSP.</P>

A<i>NuSTAR</i>Observation of the Gamma-Ray Emitting Millisecond Pulsar PSR J1723-2837

Kong, A. K. H.,Hui, C. Y.,Takata, J.,Li, K. L.,Tam, P. H. T. American Astronomical Society 2017 The Astrophysical journal Vol.839 No.2

<P>We report on the first NuSTAR observation of the gamma-ray emitting millisecond pulsar binary PSR J1723-2837. X-ray radiation up to 79 keV is clearly detected, and the simultaneous NuSTAR and Swift spectrum is well described by an absorbed power law with a photon index of similar to 1.3. We also find X-ray modulations in the 3-10, 10-20, 20-79, and 3-79 keV bands at the 14.8. hr binary orbital period. All of these are entirely consistent with previous X-ray observations below 10 keV. This new hard X-ray observation of PSR J1723-2837 provides strong evidence that the X-rays are from the intrabinary shock via an interaction between the pulsar wind and the outflow from the companion star. We discuss how the NuSTAR observation constrains the physical parameters of the intrabinary shock model.</P>

NFATc4 and ATF3 Negatively Regulate Adiponectin Gene Expression in 3T3-L1 Adipocytes

Kim, H. B.,Kong, M.,Kim, T. M.,Suh, Y. H.,Kim, W.-H.,Lim, J. H.,Song, J. H.,Jung, M. H. American Diabetes Association 2006 Diabetes Vol.55 No.5

<P>Expression of adiponectin decreases with obesity and insulin resistance. At present, the mechanisms responsible for negatively regulating adiponectin expression in adipocytes are poorly understood. In this investigation, we analyzed the effects of 5' serial deletion constructs on the murine adiponectin promoter. Here, we identified the repressor region located between -472 and -313 bp of the promoter. Removal of the putative nuclear factor of activated T-cells (NFATs) binding site increased the promoter activity, and overexpression of NFATc4 reduced the promoter activity. Treatment with the calcium ionophore A23187, an activator of NFAT, reduced mRNA as well as promoter activity. The binding of NFATc4 to the promoter was associated with increased recruitment of histone deacetylase 1 and reduced acetylation of histone H3 at the promoter site. In addition, binding of activating transcription factor 3 (ATF3) to the putative activator protein-1 site located adjacent to the NFAT binding site also repressed the promoter activity. Treatment with thapsigargin, an inducer of ATF3, reduced both mRNA and promoter activity. Importantly, the binding activities of NFATc4 and ATF3, increased significantly in white adipose tissues of ob/ob and db/db mice compared with controls. Taken together, this study demonstrates for the first time that NFATc4 and ATF3 function as negative regulators of adiponectin gene expression, which may play critical roles in downregulating adiponectin expression in obesity and type 2 diabetes.</P>

Synthesis of triarylamine-based alternating copolymers for polymeric solar cell

Lee, J.,Cha, H.,Kong, H.,Seo, M.,Heo, J.,Jung, I.H.,Kim, J.,Shim, H.K.,Park, C.E.,Kim, S.Y. IPC Science and Technology Press 2014 Polymer Vol.55 No.19

Two donor-acceptor alternating copolymers based on electron-rich triarylamine, di(1-(6-(2-ethylhexyl))naphthyl)phenylamine (DNPA), and electron-deficient benzothiadiazole and benzoselenadiazole derivatives were designed and synthesized via Suzuki coupling reaction. The resulting triarylamine-based alternating copolymers PDNPADTBT and PDNPADTBS showed good solubility in common organic solvents and good thermal stability. The optical band gaps determined from the onset absorption were 1.93 and 1.81 eV, respectively. By introducing the naphthalene ring into the triarylamine, copolymers had relatively deep HOMO energy levels of -5.48 and -5.45 eV, which led to a high open circuit voltage (V<SUB>oc</SUB>) and good air stability for photovoltaic application. Bulk heterojunction solar cells were fabricated with a structure of ITO/PEDOT-PSS/copolymers-PC<SUB>70</SUB>BM/LiF/Al by blending the copolymer with PC<SUB>70</SUB>BM. Both blend systems showed remarkably high V<SUB>oc</SUB> near 0.9 V, and the highest performance of 2.2% was obtained from PDNPADTBT, with V<SUB>oc</SUB> = 0.88 V, J<SUB>sc</SUB> = 7.4 mA/cm<SUP>2</SUP>, and a fill factor of 34.4% under AM 1.5 G.

Fabrication and electrochemical properties of hemisphere structured 3D Li(Li0.2Mn0.54Co0.13Ni0.13)O2 cathode thin film for all-solid-state lithium battery.

Yim, H,Kong, W Y,Yoon, S J,Kim, Y C,Choi, J W American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.5

<P>The Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode thin films were deposited on planar, hemisphere, linked hemisphere, and isolated hemisphere structured Pt current collector thin films to investigate the effect of 3-dimensional (3-D) structure for the electrochemical properties of active cathode thin films. The films of linked hemisphere structure shows the highest initial discharge capacity of 140 microA h/cm2-microm which is better than those of planar (62 microA h/cm2-microm), hemisphere (94.6 microA h/cm2-microm), and isolated hemisphere (135 microA h/cm2-microm) films due to increase of surface area for cathode thin films. Linked hemisphere shows the biggest capacity and the best retention rate because 6 nanobridges of each hemisphere bring strong connection.</P>