• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.48 no.1
• /
• pp.100-110
• /
• 2016

Alkaline Peroxide Mechanical Pulping (APMP) of Pinus densiflora harvested from domestic mountains was explored. APMP contributes to various advantages including pulp quality, elimination of the need for a bleaching process, and energy savings. Sequential treatment of impregnation of bleaching chemicals and refining not only overcome the concern of alkaline darkening of wood chips during chemical impregnation, but it also brightens the chips to the desired brightness levels suitable for writing and printing papers. APMP pulping from Pinus densiflora was greatly influenced by the dosage levels of hydrogen peroxide and sodium hydroxide. Alkaline peroxide treatment was carried out by applying one of three levels of hydrogen peroxide (1.5, 3, and 4.5% based on the oven-dried weight of the wood chips) and one of three levels of sodium hydroxide (1.5, 3, and 4.5% based on the oven-dried weight of the wood chips). Other chemicals including a peroxide stabilizers and metal chelation were constantly added for all treatments. Chemical treatment with a liquor-to-wood ration of 9:1 was carried out in a laboratory digestor. Compared to BTMP, APMP pulping displayed outstanding characteristics including the less requirement of refining energy, the better improvement of tensile strength, the more reduction of shives, and the greater increase of pulp brightness. In particular, when 4.5% of hydrogen peroxide with impregnation during 90 minutes was used, the brightness of APMP reached 64.9% ISO. Even though bulk of APMP was decreased with the increase of sodium hydroxide, a better and improved balance could be achieved between optical and strength properties. The spent liquor obtained from the discharge of the impregnation process at the dosage level of 4.5% hydrogen peroxide exhibited an equal level of residual peroxide with BTMP. In conclusion, APMP pulping showed successful results with Pinus densiflora due to its better response to the development of optical and physical properties compared to TMP pulping.

• The Journal of Korean Society of Virology
• /
• v.26 no.2
• /
• pp.141-150
• /
• 1996

본 연구에서는 $CD4^+$ T 세포를 일회성으로 감염시킬 수 있고 $CD4^+$ T 세포에 HIV-1 envelope 유전자를 전달할 수 있는 바이러스 입자를 생산하는 HIV-1 complementation system을 개발하였고 이 system을 이용하여 $CD4^+$ T 세포에 선택적으로 HIV-1 envelope 당단백질을 발현시켰다. 이 system은 Gag/Gag-Pol expressor와 Env expressor로 구성되어있다. Gag/Gag-Pol expressor는 바이러스 입자 생산에 필요한 구조단백질과 기능단백질을 발현시키지만 packaging signal이 결핍되어 바이러스 입자로 유전자가 들어가지 못하도록 제조되었다. Env expressor는 Tat, Rev와 envelope 당단백질을 발현시키고 packaging signal을 갖고 있어 바이러스 입자로 envelope 유전자가 들어가도록 제조되었다. Gag/Gag-Pol expressor로부터 Gag와 Gag-Pol의 발현은 Rev 단백질을 요구하였고 Env expressor로부터 Rev 단백질 이 제공될 때 Gag와 Gag-Pol 단백질은 효율적으로 발현되었다. Gag/Gag-Pol과 Env expressor로 cotransfection된 COS-1 세포에서 $CD4^+$ T 세포를 일회성으로 감염시킬 수 있는 바이러스 입자가 생산되었다. 생산된 바이러스 입자는 $CD4^+$ T 세포에 HIV-1 envelope 유전자를 전달하여 envelope 당단백질을 발현시켰고 복제 가능한 자손 바이러스의 생성을 유도하지 못하였다. 본 연구에서 개발된 방법은 $CD4^+$ T 세포에서 envelope 당단백질의 기능을 분석하고 관심 있는 유전자를 $CD4^+$ T 세포에 전달하는 바이러스 입자의 생산에 이용할 수 있다.

• Journal of the Korean Applied Science and Technology
• /
• v.26 no.1
• /
• pp.80-86
• /
• 2009

This research was performed to evaluate heavy metal leaching characteristics of the sludge from paper mill process with sintering temperature. Heavy metal leaching of the sludge was characterized with Korean Leaching Test and Toxicity Characteristic Leaching Procedure. The test sludge was composed of 70.72% of moisture, 9.5% of volatile solids and 9.76% of fixed solids. As a result of XRF analysis, Fe was the highest inorganic element in approximately 83%, which implies the recycling possibility of the sludge in reuse of Fenton chemicals and artificial lightweight aggregate. Leaching of heavy metals from sintered sludge was lower than the dry ones. However, there was no significant difference in leaching characteristics between the sludges sintered at $350^{\circ}C$ and $650^{\circ}C$. Zn and Fe were leached more greatly in TCLP and KLT methods respectively.

• Journal of Korea Water Resources Association
• /
• v.45 no.10
• /
• pp.997-1008
• /
• 2012

To construct the practical forecast and warning system for distant tsunamis suitable for Korea the state-of-art of the forecast and warning systems of United States and Korea is investigated, and the action conducted by Korea for the case of 2011 East Japan Tsunami is also analysed. The tsunami sources and propagation characteristics of distant tsunamis that affect the Korean coastal area are considered along with the capability of earthquake monitering and numerical simulation and the available experts to propose the effective forecast and warning system for distant tsunamis.

• Korean Journal of Veterinary Research
• /
• v.55 no.1
• /
• pp.53-56
• /
• 2015

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis. This study was conducted to clarify the molecular characteristics of BLVs obtained from a specific region in Korea. Proviral BLVs were detected in anti-BLV antibody-positive blood samples by PCR. Env and gag fragments were sequenced and compared to previously published reference sequences. Analysis of the env gene sequence revealed that the YI strain was highly similar to genotype 1, including United States and Japanese strains. The gag gene sequence had the highest degree of similarity with a Japanese strain.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.111-116
• /
• 2008

콘관입시험(CPT)은 의사정적상태로 수행되는 현장시험방법으로서, 각종 기초구조물의 설계와 더불어 지반조사를 위한 대표적 방법으로 널리 적용되고 있다. 본 논문에서는 콘관입시험결과를 이용하여 사질토 지반에 있어서 지반강도의 상세평가법을 제안하고자 한다. 사질토의 강도는 상대밀도와 응력상태에 따라 변하는 상태의존적 성질을 나타내고 있으나, 이러한 역학적 성질은 실험실 내에서만 측정이 가능한 상태이며, 현장강도의 경험식이나, 대표강도의 평가만이 제안되어 있는 실정이다. 따라서 본 연구에서는 대표적 현장시험방법인 CPT를 이용하여 다이러턴시 특성 평가가 가능하며, 다양한 지반특성치가 반영될 수 있는 현장강도의 상세평가법을 제안하고자 한다. 이를 위해 실내삼축압축시험을 통해 얻어진 강도특성과 역학특성치들을 분석하였으며, 이를 토대로 수정 다일러턴시 평가법을 제안하였다. 제안된 방법의 검증을 위해 가압토조를 이용한 콘관입시험을 수행하였으며, 측정값과의 비교분석을 수행하였다.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.492-497
• /
• 2008

The objective of this research is an investigation of engineering properties of weathered granite soil mixed with Phosphogypsum and recycled EPS beads as an light-weighted soil. A series of geotechnical laboratory tests including physical index test, compaction test, CBR test and direct shear test were performed for various mixing ratios. Based on the laboratory test results, it was found that the maximum dry unit weight of the light weight soil ranges $1.46{\sim}1.61g/cm^3$ and the maximum dry unit weight decreases about 11~19.3% with the increase of amount of the recycled EPS beads and the optimum moisture content increase. Since the CBR values of the light weight soil ranges 10.4~18.4%, the light weight soil mixed with Phosphogypsum and recycled EPS beads can be used as a light weight backfill material on the soft soil.

• Korean Journal of Microbiology
• /
• v.21 no.2
• /
• pp.61-70
• /
• 1983

Synchronized cat kidney cells chronically infected with feline leukemia virus (FeLV) were used to study virus production, the synthesis of group specific antigen (gag) and envelope (env) proteins, the expression of env protein on the cell surface during the cell cycle, and the stability of viral RNA. As detecting method, we developed the radioimmunoassay (RIA) system using beta-emission of $^{131}I$ and demonstrated the validity of this system by comparison with routine RIA system using gamma-emission of $^{125}I$. The produced virus was analysed by developed RIA interval was determined by measuring reverse transcriptase activity. The results show that infected cells produce the complete virus particle containing products of gag, env and pol genes of FeLV, and maximum virus production occurs during mitosis of synchronized cells. Labeling of the cell surface of synchronized cells with $^{131}I$ shows that the amount of $gp70^{env}$ on the cell surface parallels cellular gorwth. Therefore, the cell cycle-dependent release of virus is not petition RIA of synchronized cells with $^{131}I$ labeled viral proteins synthesis during the cell cycle. The rate of synthesis of gag protein shows three peaks, corresponding to the $G_1,\;late\;S\;and\;late\;G_2$ phases of cell cycle. But the rate of synthesis of env protein dose not change, suggesting that in these cells the synthesis of these two gene products in controlled seperately. In Actionomycin D treated cells, the synthesis of viral proteins decreased sharply from 8 hours after treatment, and the late S and $G_2$ peaks of gag protein synthesis were disappeared. This shows the stability of viral RNA for about 6 hours in the absence of continuing viral RNA synthesis.

• Proceedings of the KSEEG Conference
• /
• 2003.04a
• /
• pp.7-14
• /
• 2003

The precious-meta] mineralization of epithermal type in the Korean Peninsula, which is spread over a broader range of ca. 110 to 60 Ma with a major population between 90 and 70 Ma, mainly occurred along the NE-trending major strike-slip fault systems (i.e., the Gongju and Gwangju ones) that commonly include volcano-tectonic depressions and calderas. The occurrence of epithermal mineralization during Late Cretaceous clearly indicates that the geologic setting of the Korean Peninsula changed to the favorable depth of ore formation with very shallow-crustal environments (〈1.0 kb) accompanied with gold-silver (-base-meta]) mineralization. Epithermal gold-silver deposits in Korea are primarily distinguished as sediment-dominant and volcanic-dominant basins by using criteria of varying alteration, ore and gangue mineralogy deposited by the interaction of different ore-forming fluids with host rocks and meteoric waters. These differences between the central and southern portions are causally linked to the tectonic evolution of the Peninsula during the Cretaceous time. In the Early Cretaceous, the sinistral strike-slip movements due to the oblique subduction of the Izanagi Plate resulted in the Gongju and Gwangju fault systems in the central portion of the Korean Peninsula, which was accompanied with a number of sediment-dominant basins formed along these faults. During the Late Cretaceous, the mode of convergence of the Izanagi Plate changed to northwesteward so that orthogonal convergence occurred with a calc-alkaline volcanism. As results, volcanic-dominant basins were developed in the southern portion of the Peninsula, accompanied with volcano-tectonic depressions and caldera-related fractures. The magmatism and related fractures during Late Cretaceous may play an important role in the formation of geothermal systems. Thus, such fault zones may be favorable environments for veining emplacement that is closely related to the precious-metal mineralization of epithermal type in the Korean Peninsula.

• Advances in concrete construction
• /
• v.15 no.3
• /
• pp.161-170
• /
• 2023

Ultra-high-performance concrete (UHPC) is produced using high amount of cementitious materials, very low water/cementitious materials ratio, fine-sized fillers, and steel fibers. Due to the dense microstructure of UHPC, it possesses very high strength, elasticity, and durability. Besides that, the UHPC exhibits high ductility and fracture toughness due to presence of fibers in its matrix. While the high ductility of UHPC allows it to undergo high strain/deflection before failure, the high fracture toughness of UHPC greatly enhances its capacity to absorb impact energy without allowing the formation of severe cracking or penetration by the impactor. These advantages with UHPC make it a suitable material for construction of the structural members subjected to special loading conditions. In this research work, the UHPC mixtures having three different dosages of steel fibers (2%, 4% and 6% by weight corresponding to 0.67%, 1.33% and 2% by volume) were characterized in terms of their mechanical properties including facture toughness, before using these concrete mixtures for casting the slab specimens, which were tested under high-energy impact loading with the help of a drop-weight impact test setup. The effect of fiber content on the impact energy absorption capacity and central deflection of the slab specimens were investigated and the equations correlating fiber content with the energy absorption capacity and central deflection were obtained with high degrees of fit. Finite element modeling (FEM) was performed to simulate the behavior of the slabs under impact loading. The FEM results were found to be in good agreement with their corresponding experimentally generated results.