• Korean Journal of Microbiology
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• v.32 no.3
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• pp.238-244
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• 1994

To investigate the bacterial potentials for utilizing dissolved organic matter in highly eutrophic estuary, the annual fluctuations of microbiological and physicochemical environmental parameters were analyzed in Naktong River Estuary. Total bacterial number ranged from 0.33 to $2.09{\times}10^7$ cells/ml, and correlated with the heterotrophic bacterial numbers in more eutrophic sites, especially. Bacterial biovolume and biomass varied between 0.064 and 0.156 2.09${\mu}m^3$/cell, 0.163 and 1.036 ${\mu}g$-C/ml, respectively. Bacterial secondary productivity ranged from 0.24 to 60.86 ${\mu}g$-C/l/h, and showed high correlations with the environmental parameters of pollution indicator. The seasonal variation pattern of bacterial productivity in freshwater sites was high in winter and low in summer, which was interpreted as the results of pollution loads varied with the amount of rainfall. In seawater site, the pattern was different from those of freshwater sites; high in summer and low in winter. In this site, the values of bacterial productivity showed positive correaltions with chlorophyll a, heterotrophic bacterial number, and temperature (r>0.5, p<0.05). These results suggested that the main source of organic matter which influences the bacterial productivity may be allochthonous materials in the upper freshwater zone of Naktong River Barrage, and autochthonous algal excretory products in the lower seawater zone of Naktong River Barrage.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.394-405
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• 2017

The predominant concern of the study consist of: (1) the effect of young Chinese's consuming of Korean cultural wave contents including Korean TV drama, film, and K-pop on their anti-Korean sentiment; (2) the second-order mediating effects of both liking for Korean wave and positive perceptions of Koreans. The research is based on a survey conducted with 695 chinese people between high-teen and 20's, located in eleven cities of seven provinces. The notable findings are as follow: First, the higher consuming of Korean cultural wave contents, the higher anti-Korean sentiment. Second, young Chinese, consuming more Korean cultural contents, show more liking for Korean wave. The more favor of Korean cultural contents, the more positive perceptions of Koreans. The more liking for Koreans wave contests and the more positive perception of Koreans, the less anti-Korean sentiment. Therefore, it is proved that liking for Korean cultural wave contents and perceiving Koreans with a positive view are important mediator to reduce the anti-Korean sentiment. Some practical implications are discussed based on this study's findings above.

• Korean Journal of Cleft Lip And Palate
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• v.6 no.1
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• pp.17-25
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• 2003

Correction of the cleft-lip nasal deformity is a difficult task that requires clear understanding of the associated complex anatomy and function as well as the operation time, the selection of an operation method, On the expectation that it helps enhance understanding the current trend of cleft-rhinoplasty, authors analyzed secondary rhinoplasty between 1999 and 2002, In both the unilateral and bilateral cleft lip rhinoplasty, we reviewed the timing of repair, site of correction and it's major technique, incision or approach method, autogenous cartilage graft method, All patients with a septal deviation did not have a septal surgery, We were active in alar and nasal tip surgery and passive in septal and dorsal deformity correction, And for children, we used a conservative method but for adults, we used radical approach, Most surgeries are focused on esthetic goal and we thought that objective evaluation for nasal obstruction was needed for bener and predictable outcome.

• Journal of Gastric Cancer
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• v.9 no.4
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• pp.256-261
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• 2009

Purpose: With the development of diagnostic techniques, second primary neoplasms such as synchronous or metachronous cancers in gastric cancer patients are being increasingly found. In this study, we investigated the clinicopathological features and clinical significance of gastric neoplasms combined with synchronous and metachronous cancers. Materials and Methods: 1,048 patients who were diagnosed with gastric cancer in Chosun University Hospital from January 1998 to March 2008 were retrospectively reviewed. Results: 38 of the 1,048 patients with gastric cancer (3.6%) had synchronous and metachronous cancers. Of the 38 patients, 16 patients (42.1%) had synchronous cancer and 22 patients (57.9%) had metachronous cancer. The average time interval between gastric cancer and the secondary primary cancer was $27.08{\pm}31.25$ months. The most common second primary neoplasm was lung cancer (8/38, 21.1%), followed by colorectal cancer (8/38, 21.1%). Among the 27 patients who underwent surgical resection for gastric cancer, 5 patients (18.5%) were in the synchronous group and 22 patients (81.5%) were in the metachronous group. The mean survival time of the 38 patients was 49.8 months. The mean survival time was 24.6 months for the synchronous cancer patients and 68.1 month for the metachronous cancer patients. The 3 year survival rate of the synchronous group and the metachronous group was 33.3% and 81.1%, respectively. Conclusion: We must pay attention on the preoperative workup for synchronous cancer and on the postoperative follow-up for metachronous cancer in gastric cancer patients.

• Clinical and Experimental Pediatrics
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• v.53 no.2
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• pp.146-151
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• 2010

Purpose : The purpose of this study was to evaluate the timing of puberty and the factors inducing advanced puberty in elemental school students of low grades. Methods : The 1st, 2nd, and 3rd grade elemental students from the Goyang province were randomly selected, and their sexual maturation rate was assessed by physical examination. After obtaining an informed consent, a questionnaire was administered to the parents; eating habits, lifestyle, use of growth-inducing medication, and present illness of the students were evaluated to determine the factors that induced advanced puberty. The data were statistically analyzed. Results : We selected 170 children and the girls:boys sex ratio was 1.2:1. Two 9-year-old boys were in genital stage 2. Two (14.3%) 6-year-old girls, 6 (19.4%) 7-year-old girls, 15 (39.6%) 8-year-old girls, and 4 (57.1%) 9-year-old girls were in breast stage 2. The average pubertal timing predicted for girls was $9.11{\pm}1.86$ years. The main factors influencing pubertal timing were obesity scale, frequency of eating fast food, and the use of growth-inducing medication. A high rating on the obesity scale and high frequency of eating fast food indicated advanced stage of puberty. Growth-inducing medication induced puberty through obesity. Conclusion : We proposed that predictive average pubertal timing in girls was 9.11${\pm}$1.86 years, which was consistent with the previously reported findings from abroad. The significant influencing factors in advanced puberty were obesity scale and frequency of fast food.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.629-638
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• 2009

In this paper, the existing formulas of the step-by-step method were generalized for effective estimation of responses of complicated composite sections due to long-term deformation of concrete. The initial transformed section properties of the composite section were derived from material and section properties of concrete section and sections which confine the longterm deformation of concrete. The transformed section properties at each step were derived from the effective modulus of elasticity considered the creep coefficient variation. Improved formulas of the step-by-step method for generalized responses were derived by introducing 5 generalized parameters. The formulas can be more simplified by applying constant increment of creep coefficient at each step. The constant increment of creep coefficient at each step can also reduce computing time and make equal computing error of each step. The generalized responses for axial elastic strain of concrete section were most sensitive to the area rate of concrete section, and the ratio of the second moment of the confining section area was more sensitive than that of the concrete section. Those for elastic curvature of concrete section were most sensitive to the ratio of the second moment of concrete section area.

• Journal of Hydrogen and New Energy
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• v.14 no.3
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• pp.217-228
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• 2003

Li 이차 전지 음극용 활물질인 $Co_3O_4$의 초기 충방전 효율을 향상시키기 위해 chemical reduction method나 mechanical milling법을 이용하여 $Co_3O_4$에 Ni을 첨가하여 $Ni-Co_3O_4$, 복합물을 제조하였다. 그 결과 초기 충방전 효율이 약 69%에 불과한 $Co_3O_4$에 비해 mechanical milling법을 이용하여 제조된 $Ni-Co_3O_4$ 복합물은 약 79%이상의 대폭 향상된 초기 충방전 효율 특성을 나타내었다. 하지만 chemical reduction method를 이용하여 제조된 $Ni-Co_3O_4$ 복합물은 약 71%의 초기 충방전 효율 특성만을 나타내었다. SEM 분석을 통해 각 물질의 표면 형상을 관찰한 결과 mechanical milling법과 chemical reduction method를 통해 제조된 $Ni-Co_3O_4$ 복합물에서는 $Co_3O_4$ 표면에 분포된 Ni의 균일성의 차이가 존재하였다. $Co_3O_4$가 $Li_2O$의 분해, 형성에 의해 충방전되고 Ni이 $Li_2O$의 분해를 촉진시키는 효과를 가지고 있음을 고려할 때 이러한 균일성의 차이는 결국 Ni 과 $Co_3O_4$ 사이의 접촉면적의 차이로 이어져 $Ni-Co_3O_4$ 복합물의 초기 충방전 효율 특성이 그 제조 방법에 따라 달라지는 것으로 보인다.

• Resources Recycling
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• v.24 no.6
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• pp.9-16
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• 2015

In a recycling scheme of spent lithium ion batteries, a co-precipitation process for the re-synthesis of precursor is essential after the leaching of lithium ion battery scraps. In this study, the effect of ammonia as impurity during the co-precipitation process was investigated in order to re-synthesize a precursor of Ni-rich cathode active material $LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$ (NCM 622). As ammonia concentration increases from 1 M (the optimum condition for synthesis of the precursors based on 2 M of metal salt solution) to 4 M, the composition of obtained precursors deviates from the designed composition, most notably for Ni. The Ni co-precipitation efficiency gradually decreases from 100% to 87% when the concentration of ammonia solution increases from 1 M to 4 M. Meanwhile, the morphological properties of the obtained precursors such as sphericity, homogeneity and size distribution of particles were also investigated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.80-85
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• 2019

Vanadium dioxide is a well-known metal-insulator phase transition material. Lots of researches of vanadium redox flow batteries have been researched as large scale energy storage system. In this study, vanadium oxide($VO_x$) thin films were applied to cathode for lithium ion battery. The $VO_x$ thin films were deposited on Si substrate($SiO_2$ layer of 300 nm thickness was formed on Si wafer via thermal oxidation process), quartz substrate by RF magnetron sputter system for 60 minutes at $500^{\circ}C$ with different RF powers. The surface morphology of as-deposited $VO_x$ thin films was characterized by field-emission scanning electron microscopy. The crystallographic property was confirmed by Raman spectroscopy. The optical properties were characterized by UV-visible spectrophotometer. The coin cell lithium-ion battery of CR2032 was fabricated with cathode material of $VO_x$ thin films on Cu foil. Electrochemical property of the coin cell was investigated by electrochemical analyzer. As the results, as increased of RF power, grain size of as-deposited $VO_x$ thin films was increased. As-deposited thin films exhibit $VO_2$ phase with RF power of 200 W above. The transmittance of as-deposited $VO_x$ films exhibits different values for different crystalline phase. The cyclic performance of $VO_x$ films exhibits higher values for large surface area and mixed crystalline phase.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.521-529
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• 2018

This study was conducted to investigate the natural origin of fluorine contained in the rocks within the Eulwangsan area via petrological and mineralogical analyses. The main geology of the Yongyudo Eulwangsan area is Triassic biotite granite. Biotite granite and mylonite are the major rock types containing fluorine at high levels (up to 1,700 and 2,400 mg/kg for biotite granite and mylonite, respectively). In the case of the biotite granite, a high concentration of fluorine can be contributed to fluorite, and the results of microscopic analyses show that the fluorite was observed as small veinlets filling cleavages and micro-fractures within alkali-feldspars and plagioclases, or observed together with quartz in ore veins, indicating the secondary formation of fluorite by hydrothermal fluids. In mylonite, on the other hand, a high fluorine concentration is attributable to sericite. Microscopic analyses revealed that the boundary between sericite and surrounding quartz was not clear, the sericite occurred filling the micro-fractures of quartz and encapsulating small quartz cataclasts. These results indicate that the sericite was also formed as a result of hydrothermal alteration. Consequently, it is speculated that the high fluorine level in the rocks of the Eulwangsan area of Yongyudo is of natural origin due to hydrothermal processes.