• Journal of Radiation Protection and Research
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• v.23 no.1
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• pp.33-47
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• 1998

Using a combination of an X-ray generator Installed in radiation calibration laboratory of Korea Atomic Energy Research Institute (KAERI) and a series of 8 radiators and filters described in ISO-4037, monoenergetic fluorescent X-rays from 8.6 keV to 75 keV were produced. This fluorescent X-rays generated by primary X-rays from radiator were discriminated $K_{\beta}$ lines with the aid of filter material and the only $K_{\alpha}$ X-rays were analyzed with the high purity Ge detector and portable MCA. The air kerma rates were measured with the 35 co ionization chamber and compared with the calculational results, and the beam uniformity and the scattered effects of radiation fields were also measured. The beam purities were more than 90 % for the energy range of 8.6 keV to 75 keV and the air kerma rates were from 1.91 mGy/h (radiator : Au, filter : W) to 54.2 mGy (radiator : Mo, filter : Zr) at 43 cm from center of the radiator. The effective area of beam at the measurement point of air kerma rates was 12 cm ${\times}$ 12 cm and the influence of scattered radiation was less than 3 %. The fluorescent X-rays established in this study could be used for the determination of energy response of the radiation measurement devices and the personal dosemeters in low photon energy regions.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.603-606
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• 1991

The crystal structure of Probenecid has been determined from 2574 independent reflections collected on an automatic ENRAF-NONIUS CAD-4 diffractometer using graphite-monochromated $Mo-K{\alpa}$ radiation. The crystal is triclinic, space group P$\bar{1}$ with unit cell dimensions a = 7.535(2)${\AA}$, b = 18.473 (5)${\AA}$, c = 5.317(9)${\AA}$, ${\alpha} = 92.00(5)^{\circ}$, ${\beta} = 99.02(5)^{\circ}$, ${\gamma} = 94.89(2)^{\circ}$, V = 727.4(2)${\AA}^3$, Z = 2, $D_m$ = 1.310, $D_x$ = $1.302 gcm^{-3}$, ${\mu}$ = $1.88 cm^{-1}$, F(000) = 304, and T = 298 K. Final R = 0.0676 and $R_w$ = O.0630 for 1209 reflections > 5${\sigma}(F_o)$. In the spacial arrangement about N(13), the sum of bond angles about nitrogen is 350.9° and the nitrogen lies only 0.268(6)${\AA}$ out of S(1)-C(14)-C(17) plane. The S(1)-C(4) distance is 1.792(6)${\AA}$ and the C(4)-S(1)-N(13) angle is $106.5(3)^{\circ}$. The overall conformation of the molecule is folded with respect to sulfur.

• Economic and Environmental Geology
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• v.41 no.3
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• pp.287-297
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• 2008

In order to estimate the preliminary development feasibility according to the commodity, the content of 8 strategic metallic commoditites(Pb, Zn, Cu, Fe, Mo, W, Au, U) in 68 ore specimens obtained from 34 metallic mines within the Taebaegsan-Hwanggangri mineralized zone were analyzed. Analytical results are as follows. The ore specimen of Sangdong mine contained 23% copper(cut-off grade=0.7%) and those of Cheongil and Samhwanghak mines contained average 5% zinc(cut-off grade=2.0%). Especially, the detailed investigation on the above-mentioned mines is required. And, in case of molybdenum(cut-off grade=0.02%) content in Yeonhwa No. 2(0.04%) and Hong-cheon mine(0.02%), and lead(cut-off grade=0.58%) content in Wongasa mine(0.70%), and gold(cut-off grade=10ppm) content in Dongmyoung(279ppm) and Samhwanghak mine(251ppm), it is required to elastically carry out the revaluation on reopening of mines in terms of the international metal price. On the other hand, in case of uranium, iron and tungsten, it is thought that there are no mines with the development potential value in this study.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.812-817
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• 1992

Fluorometholone $(C_{22}H_{29}FO_4)$, M.W. = 376.5, monoclinic, $P2_1$, a = 6.410(4), b = 13.431(3), c = 10.996(3)$\AA$, $\beta$ = 92.81$(3)^{\circ}$, Z = 2, F(000) = 404, T = 292K, $\lambda$(Mo-$K_\alpha$) = 0.7107$\AA$, $\mu$ = 0.57$cm^{-1}$, $D_c$ = 1.32 $g/cm^3$, $D_m$ = 1.31 $g/cm^3$ and final R = 0.032 for 1769 observed reflections. All bond lengths and angles are within normal limits. Ring A is almost planar, B ring has a highly symmetrical chair conformation and C ring is in a distorted chair conformation. Ring D is in a intermediate conformation between 13$\alpha$-14$\beta$-half-chair and 13$\alpha$-envelope. Torsion angle C(16)-C(17)-C(20)-O(20) of $-7.9^{\circ}$ is a lower value than those of $-31.9^{\circ}$ and $-16.5^{\circ}$ for 9-fluoro-6-methylprednisolone I and II respectively.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.774-780
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• 1998

For the stabilization of the spinel structured $LiMn_2O_4$, a fraction of manganese was substituted with various metals such as Mg, Fe, V, W, Cr, Mo with Mn that had a similar ionic radii ($LiM_xMn_{2-x}O_4(0.05{\leq}x{\leq}0.02)$). The $LiM_xMn_{2-x}O_4$ showed a substantial improvement as lower capacity loss than that of the spinel structured $LiMn_2O_4$ when it was used as a cathode material. And with the partial substitution, the chemical diffusion coefficient for $LiMg_{0.05}Mn_{1.9}O_4$ and $LiCr_{0.1}Mn_{1.9}O_4$ was increased by and order of magnitude compared to that of the $LiMn_2O_4$ with spinel structure. The results showed that significant improvement can be made on the electrochemical characteristics as the structure of the $LiMn_2O_4$ electrode material was stabilized by the partial substitution.

• Economic and Environmental Geology
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• v.52 no.5
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• pp.323-336
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• 2019

The Mesozoic activity on the Korean Peninsula is mainly represented by the Triassic post-collisional, Jurassic orogenic, and Cretaceous post-orogenic igneous activities. The diversity of mineralization by each geological period came from various geothermal systems derived from the geochemical characteristics of magma with different emplacement depth. The Cretaceous metallic mineralization has been carried out over a wide range of time periods from ca. 115 to 45 Ma (main stage; ca. 100 to 60 Ma) related to post-orogenic igneous activity, and spatial distribution patterns of most metal deposits are concentrated along small granitic stocks. The late Cretaceous metal deposits in the Gyeonggi and Yeongnam massifs are generally distributed along the boundary among the Gongju-Eumseong fault system and the Yeongdong-Gwangju fault system and the Gyeongsang Basin, most of them are in the form of a distal epithermal~mesothermal Au-Ag vein or a transitional mesothermal Zn-Pb-Cu vein. On the other hand, diverse metal commodities in the Taebaeg Basin, the Okcheon metamorphic belt and the Gyeongsang Basin are produced from various deposit types such as skarn, carbonate-replacement, vein, porphyry, breccia pipe, and Carlin type. In the late Cretaceous metallic mineralization, various mineral deposits and commodities were induced not only by the pathway of the hydrothermal solution, but also by the diversity of precipitation environment in the proximity difference of the granitic rocks. The diversity of these types of Cretaceous deposits is fundamentally dependent on the geochemical characteristics such as degree of differentiation and oxidation state of related igneous rocks, and ore-forming fluids generally exhibit the evolutionary characteristics of intermediate- to low-sulfur hydrothermal fluids.

• Journal of Animal Science and Technology
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• v.45 no.6
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• pp.975-986
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• 2003

Present study was conducted to investigate the effect of the level of concentrates and pasture grazing in 36 autumn born Hanwoo heifers(initial body weight, 119.7${\pm}$25.6kg) for 426d including 195d for a pasture stage. The animals were fed commercial concentrates at a rate of 0.5%(T1), 1.0%(T2), 1.5%(T3) and 2.0%(T4) of body weight, respectively, for pre- and post-pasture. 1. Mean daily gains by treatments were 0.348, 0.403, 0.450 and 0.501kg for T1, T2, T3 and T4, respectively, indicating that increases in concentrates intake was associated with the daily gain of grazing Hanwoo heifers. However, the mean daily gain was the highest for T2 during the pasture stage. 2. TDN intakes per 1kg gain were, on average, 8.61kg for the entire experimental period and 9.22kg for the pasture stage, respectively. In addition, the rate of roughage to concentrate during the entire experimental period was 49.6 to 68.2%(mean 58.5%). 3. Age reached 225 and 250kg of body weight was, on an average, 15.1mo. and 17.6mo., respectively, indicating that increasing the level of concentrates feeding(by 0.5% of body weight) reduced the first pregnancy by 0.9 mo. Ages and body weight for first service were 19.5mo. and 272.2 kg, respectively. Mean pregnant rate of total heads was approximately 52.8%, but appeared to 66.6% for T3 and T4. Therefore, it may be concluded that the optimum level of concentrates for autumn born Hanwoo heifers is 1.8% of body weight for indoor feeding on rice straw-based diet and 1.5% of body weight for a pasture stage, respectively.

• Economic and Environmental Geology
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• v.25 no.3
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• pp.245-258
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• 1992

The variations of certain major and trace elements of the Onjong granite mass was studied on the basis of petrological and geochemical characteristics and compared with those of the Eonyang-Yucheon granite masses in order to investigate the geochemical differences of the granitic rocks in relation to mineralization between Pb-Zn ore district and Pb-Zn-Mo-W ore district in Kyeongsang basin. The Onjong granite mass is classified into granodiorite and monzo-granite, and the Eonyang-Yucheon granite masses into monzo-granite by the Streckeisen's diagram. Between both granite masses there are clear differences in contents of certain major elements and lithophile trace elements. The former have high contents of Ca (2.94%), Mg (1.66%) and Sr (365 ppm), and low contents of K (3.52%), Na (3.51%), Rb (116 ppm), Ba (640 ppm) and Li (18.9 ppm), whereas the latter have high contents of K (4.02%), Na (4.28%), Rb (145 ppm), Ba (695 ppm) and Li (19.3 ppm), and low contents of Ca (1.42%), Mg (0.43%) and Sr (161 ppm). Except for Mo, there are not clear differences in chalcophile trace elements between two granite masses: the Onjong granite mass has higher Mo content (7.1 ppm) lnan that (1.7 ppm) of the Eonyang-Yucheon granite masses, but Pb and Zn contents are similar between the Onjong granite mass (Pb=8.7 ppm, Zn=37.1 ppm) and the Eonyang-Yucheon granite masses (Pb=7.8 ppm, Zn=39.8 ppm). Ca and Sr contents of the Onjong granite mass (Ca> 1.5%, Sr> 270 ppm) are higher than those of the Eonyang- Yucheon granite masses (Ca<1.5%, Sr<270ppm), and Rb/Sr, Rb-Rb/Sr and K-Rb/Sr ratios are clearly distinguishable between the Onjong granite mass(Rb/Sr<0.51, Rb-Rb/Sr>250 and K-Rb/Sr>5.2) and the Eonyang- Yucheon granite masses (Rb/Sr>0.51, Rb-Rb/Sr<250 and K-Rb/Sr<5.0). Thus, variations of certain major and trace elements and ratios are applicable as geochemical index to distinguish the types of mineralization of the ore districts related to the Cretaceous granitic rocks in the Kyeongsang basin.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.218-223
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• 1997

At the aim of finding a Fehased amorphous alloy with a wide supercooled liquid region (${\Delta}T_{x}=T_{x}-T_{g}$) before crystallization, the changes in glass transition temperatudfI$T_{g}$ and crystallization temperature ($T_{x}$) by the dissolution of additional M elements were examined for the $Fe_{80}P_{10}C_{6}B_{4}$(x~6at%. M= transition metals) amorphous alloys. The ${\Delta}T_{x}$ value is 27K for the Fe,,,P,,,C,,R, alloy and increases to 40K for the addition of M=4at%Hf, 4at%Ta or 4at%Mo. The increase in ${\Delta}T_{x}$ is due to the increase of $T_{x}$ exceeding the degree in the increase in $T_{g}$. The $T_{g}$ and $T_{x}$ increase with decreasing electron concentration (e/a) from about 7 38 to 7.05. The decrease of e/a also implies the increase in the attractive bonding state between the M elements and other constitutent elements. It is therefore said that $T_{g}$ and $T_{x}$ increase kith increasing attractive bonding force.

• The Journal of the Acoustical Society of Korea
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• v.39 no.1
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• pp.16-23
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• 2020

In High-Intensity Focused Ultrasound (HIFU) treatment, effective localization of HIFU focus is important for developing a safe treatment plan. While Magnetic Resonance Imaging guided HIFU (MRIgHIFU) can visualize the ultrasound path during the treatment for localizing HIFU focus, it is challenging in ultrasound imaging guided HIFU (USIgHIFU). In the present study, a real-time ultrasound beam visualization technique capable of localizing HIFU focus is presented for USIgHIFU. In the proposed method, a short pulse, with the same center frequency of an imaging ultrasound transducer below the regulated acoustic intensity (i.e., Ispta < 720 mW/㎠), was transmitted through a HIFU transducer whereupon backscattered signals were received by the imaging transducer. To visualize the HIFU beam path, the backscattered signals underwent dynamic receive focusing and subsequent echo processing. From in vitro experiments with bovine serum albumin gel phantoms, the HIFU beam path was clearly depicted with low acoustic intensity (i.e., Ispta of 94.8 mW/㎠) and the HIFU focus was successfully localized before any damages were produced. This result indicates that the proposed ultrasound beam path visualization method can be used for localizing the HIFU focus in real time while minimizing unwanted tissue damage in USIgHIFU treatment.