• The Journal of the Petrological Society of Korea
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• v.21 no.2
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• pp.151-171
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• 2012

The Permo-Triassic Songrim orogeny in the Korean peninsula was a major tectonic event involving complicated continental collisions at the eastern margin of Eurasia. Based on the previous studies on the metamorphic and deformations features of the Songrim orogeny, this paper presents metamorphic and structural characteristics and timing of the Songrim orogeny in the Taebaeksan basin, and discuss about correlation of the tectono-metamorphic evolution of the Taebaeksan basin with the Okcheon basin and the Imjingang belt with a combined analysis of bulk crustal shortening direction, metamorphic P-T and T-t (time) paths. The metapelites in the Pyeongan Supergroup in the northeastern margin of the Taebaeksan basin have experienced lower-temperature/medium-pressure (LT/MP) regional metamorphism followed by high-temperature contact metamorphism due to the Jurassic granite intrusion. The earlier LT/MP regional metamorphism produced two loops of clockwise P-T-d (deformation) paths combined with four deformation events ($D_1-D_4$). The first loop concomitant with $D_1$ and $D_2$ occurred at $400-500^{\circ}C$, 1.5-3.0 kbar, and related with growth of syn-$D_1$ chloritoid and andalusite, post-$D_1$ margarite, Ca-rich syn-$D_2$ or post-$D_2$ plagioclase. The second loop accompanying $D_3$ and $D_4$ occurred at $520-580^{\circ}C$, 2.0-6.0 kbar, and associated with the growth of syn-$D_3$ garnet and staurolite, and syn-$D_4$ and/or post-$D_4$ andalusite porphyroblasts. Furthermore the syn-$D_1$ chloritoid and andalusite porphyroblasts grew during E-W bulk crustal shortening, whereas the syn-$D_3$ garnet and staurolite, and the syn-$D_4$ and/or post-$D_4$ andalusite porphyroblasts have grown under N-S bulk crustal shortening. The similarity in the characteristics and timing of the metamorphism and bulk crustal shortening directions between the Okcheon and Imjingang belts suggest that the peak metamorphic conditions tend to increase toward the western part (Imjingang belt and southwestern part of the Gyeonggi Massif) from the eastern part (Taebaeksan basin). The E-W bulk crustal shortening influenced the eastern part of the Okcheon belt, whereas the N-S bulk crustal shortening resulted in strong deformation in the Imjingang and Okcheon belts. Consequently, the Permo-Triassic Songrim orogeny in the Korean peninsula is probably not only related to collision of the North and South China blocks, but also to the amalgamation of terrane fragments at the eastern Eurasia margin (e.g., collision of the Sino-Korean continent and the Hida-Oki terrane).

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1407-1416
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• 2016

This study was conducted to investigated the effects of stocking density on growth and survival of sea cucumber, Apostichopus japonicus in the indoor multiple tank for 12 weeks. There were six treatments(stocking densities) in this experiment, i.e. 1, 2, 3, 4, 5 and 10 individuals per 10 L plastic aquarium($W41{\times}H24{\times}D11cm$, represented as D1, D2, D3, D4, D5 and D10, respectively). Each treatment had ten replicates. The results showed growth variation of sea cucumber, Apostichopus japonicus decreased with the increase of stocking densities. After the end of the experiment, no significant differences(P>0.05) between D1~D5 treatment group whereas significant differences(P<0.05) between D1 and D10 treatment group. Survival rate showed D1~D10 were 90%, 90%, 100%, 95%, 94% and 72%, respectively. Especially, significant differences(P>0.05) between D1~D5 and D10 treatment group. The results indicated optimum of stocking density for sea cucumber, Apostichopus japonicus within five individuals per 10 L plastic aquarium($0.05individuals/m^2$).

• Korean Journal of Crystallography
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• v.7 no.2
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• pp.120-125
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• 1996

Single crystals of deoxy-thymidine diphosphate-D-gluxose-4,6-dehydratase(abbreviated as dTDP-D-glucose dehydratase) from Escherichia coli Strain BL21 clone which harbors the gene of dTDP-D-glucose dehydratase in Salmonella typhimurium LT2 have been grown with and whithout substrates by sitting drop vapor diffusion at room temperature. The precipitating agent was 1.6 to 2.0 M Na, K phosphate buffer(pH 8.0). The crystals diffract to at least 2.5Å and belong to the hexagonal space group P61 with cell dimensions a=b=168.54Å, c=81.08Å. The asymmetric unit contains one dimer with a crystal volume per protein mass(VM) of 2.4Å3/Da and solvent content (Vsol) of 64% by volume.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.4
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• pp.229-239
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• 2013

Recently, device-to-device (D2D) communications have been highlighted to improve the spectral efficiency and offer various user experiences in cellular networks. In this paper, we survey standards and literatures related to the D2D technology and address various advantages of D2D technology, and the problems to be resolved before practically implemented. Especially, by considering an important interference issue between cellular and D2D links, five resource allocation and interference management scenarios are provided and their performances are evaluated through the system level simulations. The simulation results show that the use of D2D significantly improve the cell capacity and the D2D user rate due to the effects of frequency reuse and data off-loading. Notably, it is also shown that an optimal D2D communication range exists to maximize the system performance.

• Journal of Digital Convergence
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• v.14 no.3
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• pp.329-335
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• 2016

This paper's objective is to investigate the display fatigue quantitatively according to watching 2D and 3D videos on the display. Though it has been known commonly that display fatigue by 3D is greater than one by 2D, there have been few researches with an aim to measure display fatigue scientifically. Flicker fusion frequency and cybersickness degree were measured before/after sixteen subjects(Male 8, Female 8) watch the 2D, 3D images. Two dependent variables affected by 2D and 3D videos were analyzed and compared statistically based on scientific evidences and researches. 3D showed a value 4 times as much as 2D in cybersickness increase rate, and the reduction rate of 3D was 2 times as much as that of 2D.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.385-399
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• 1997

The purpose of this experiment was to determine the effects of etching with a Nd : YAG Laser on dentin, or porcelain surface on the bond strength with composite resin. The dentin specimens were devided into the following 4 groups. D1 : No treatment D2 : Etched with 10% phosphoric acid D3 : Laser etchded with 1W, 20PPs D4 : Laser etched with 2W, 20PPS The procelain specimens were devided into the following 4 groups. P1 : diamond roughened P2 : etched with HF acid P3 : Laser etched with 2W, 20PPS P4 : Laser etched with 3W, 20PPS All specimens were veneered with resin. One half of the specimens were stored in $37^{\circ}C$ water for one day and the other half were thermocycled 1000 times at temperature of $5^{\circ}C\;to\;55^{\circ}C$ at 20 seconds intervals. After that, the bonding strength of composite resin to the dentin and porcelain was measured. The surface treated state and fractured state were observed with SEM. The following results were obtained. 1. In the dentin specimens, the bond strength of group D2 was highter than that of groups D1 and D3 in the case of the specimens stored in $37^{\circ}C$ water for one day, there was a statistically significant difference between group D2 and D1, D3 (P<0.05). The bonding strength of the specimens that were thermocycled decreased in the following order : group D2,D4,D3 and then D1. 2. In the porcelain specimens, the bonding strength of groups P1,P2 were higher than that of group P3 in the case of the specimens stored in $37^{\circ}C$ water for one day (P<0.05). The bonding strength of the specimens of being thermocycled decreased in the following order : group P2,P1,P4 and then P3. 3. The groups of high bond strength had a rougher surface and a high level of microporosity with SEM findings.

• Bulletin of the Korean Chemical Society
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• v.18 no.11
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• pp.1192-1195
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• 1997

A divergent approach to 2-(hydroxymethyl)pyrrolidine-3,4-diols has been studied with 1,4-dideoxy-1,4-imino-D-arabinitol (D-AB1), a potent glycosidase inhibitor. D-AB1 was efficiently synthesized from 2,3-epoxyalcohol 6a in overall 11% yield.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.29-33
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• 2003

There are reports that the myopia progression have been difference according to myopia degree and age. In this studies, we divided into three investigated groups. The A group is the lower elementary school(50), the B group is the high elementary school(50), the C group is the junior high school(50) and the D group is the high school students(50). The myopia progression have been compared with each group and most variable terms have been investigated. We have analyzed the refraction inspection record that were investigated to put on spectacles in three years(visiting three times or more). The subject of study were 200 persons(men 100, women 100), 1. The distribution of equivalence with ages : A group -2.72D, B group -2.90D, C group -3.53D, D group -3.96D. 2. The pupillary distance have been 57.4mm(A), 59.9mm(B), 61.6mm(C), 63.4mm(D). 3. On a monthly variation : -0.02D(A), -0.045(B), -0.050D(C), -0.025(D) in men, and -0.06D(A), -0.06D(B), -0.045(C), -0.04D(D) in women. 4. After due considering monthly variation and suppose that the variatting times of spectacles degress were time of refracting inspection. The result : 3.6 month for A group, 4.8 month for B group, 5.3 month for C group and 7.7 month for D group.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.103-109
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• 2003

We have proposed the 4-Dimensional Multiple-Subcarrier Modulation with fixed bias in Optical Wireless Communications. Here, the 4-D signal vectors are derived from the optimization technique of signal waveforms maximizing the minimum distance between signal points in an n-dimensional Euclidean sphere. The resulting vectors are used in generating the output amplitude of impulse generator in a Multiple-Subcarrier Modulation scheme. We have achieved that the normalized power requirement of the proposed system is maximum 3 dB and 3.3 dB smaller than those of normal QPSK, Reserved Subcarrier, and Minimum Power scheme, respectively. Also, in the range of 1.125 ∼ 1.25 of the normalized bandwidth, the proposed system has maximum 3 dB, 2 ∼ 4 dB, 0 ∼ 3 dB smaller bandwidth requirement compare to normal QPSK, Res. Subcarrier, Min. Power schemes, respectively.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.638-643
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• 2011

The synthesis of biologically active 1H-1,4-diazepines 4a-d and 3H-1,5-benzodiazepines 5a-d in good yields, from the heterocyclization reaction of 2-(4-methylthio benzenesulfonyl)-1,3-dimethyl/1-methyl-3-phenyl/1,3-diphenyl/1-methyl-3-ethoxy propane-1,3-dione 3a-d with ethylenediamine (EDA) and o-phenylenediamine (o-PDA), respectively, in the presence of silica sulfuric acid (SSA) is described. The novel ${\beta}$-diketones/${\beta}$-ketoesters 3a-d were synthesized by the condensation reaction of 4-methylthiobenzenesulfonyl chloride 1 with various ${\beta}$-diketones/${\beta}$-ketoesters 2a-d. All structures of the newly synthesized compounds were elucidated by elemental analysis and spectral studies. The compounds 4a-d and 5a-d have been screened for antimicrobial, antifungal and anthelmintic activity.