• Toxicological Research
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• v.24 no.2
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• pp.119-127
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• 2008

The objectives of this study were to examine the lung injury and inflammation caused by manual metal arc stainless steel(MMA-SS) welding fume inhalation and to evaluate the recovery process. Sprague-Dawley rats were exposed to MMA-SS welding fumes for 2 h per day in a whole-body exposure chamber, with a total suspended particulate(TSP) concentration of $51.4{\pm}2.8mg/m^3$(low dose) or $84.6{\pm}2.9mg/m^3$(high dose) for 30 days. The animals were sacrificed after 30 days of exposure as well as after a 30-day recovery period. To assess the inflammatory or injury responses, cellular and biochemical parameters as well as cytokines were assayed in the bronchoalveolar lavage fluid(BALF). MMA-SS welding fume exposure led to a significant elevation in the number of alveolar macrophages(AM) and polymorphonuclear cells(PMN). Additionary, the values of $\beta$-n-acetyl glucosaminidase($\beta$-NAG) and lactate dehydrogenase(LDH) in the BALF were increased in the exposed group when compared to controls. After 30 days of recovery from exposure, a significant reduction in inflammatory parameters of BALF was observed between the exposed and recovered groups. Slight, but significant elevations were noted in the number of AM and PMN in the recovered groups, and AM that had been ingested fume particles still remain in the lungs. In conclusion, these results indicated that welding fumes induced inflammatory responses and cytotoxicity in the lungs of exposed rats. Fume particles were not fully cleared from lungs even after a 30-day recovery period.

• Korean Journal of Plant Tissue Culture
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• v.24 no.4
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• pp.239-256
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• 1997

Plants belonging to the category of 2n apomixis or agamospermy form embryos and seeds without the processes of normal meiosis and syngamy. Seeds produced in this way have identical genotype of their maternal parent. Three different types of agamospermy are recognized: diplospory, apospory, and adventitious (adventive) embryony. $F_1$ hybrid cultivars cannot be used as seed sources in the next ($F_2$) generation because this generation would be extremely variable as a result of genetic segregation. Hybrid vigor is also reduced in the $F_2$ generation. Therefore, parental stocks for hybrid seed production need to be maintained and cross must be continuously repeated. Agamospermic 2n apomixis would make it possible to fix the genotype of a superior variety so that clonal seeds faithfully representing that genotype could be continuously and cheaply produced independent of pollination. That is, $F_1$ hybrid seeds could be produced for many generations without loss of vigor or genotype alteration. Production of apomictic $F_1$ hybrid seed would be simplified because line isolation would not be necessary to produce seed or to maintain parental lines, and the use of male-sterile lines could be avoided. Overall, apomixis would enable a significant reduction in hybrid seed production costs. Additionally, the production of clonal seed is not only important for seed propagated crops, but also for the propagation of heterozygous fruit trees and timbers. Clonal seed would help avoid costly and time-consuming vegetative propagating methods that are currently used to ensure the large-scale production of these plants. Apomixis is scattered throughout the plant kingdom, but few important agricultural crops possess this trait Therefore, most research to date has centered on introgressing the trait of apomixis into agricultural crops such as wheat, maize, and some forage grasses from wild distant relatives by traditional cross breeding. The classical breeding approach, however is slow and often impeded by many breeding barriers. These problems could be surmounted by taking mutagenesis or molecular approach. Arabidopsis thaliana is a tiny sexually reproducing plant and is convenient in constructing and screening in molecular researches. Male-sterile mutants of Arabidopsis are particularly suitable genetic background for mutagenesis and screening for apomictic mutants. Molecular approaches towards isolating the genes controlling the apomictic process are feasible. Direct isolation of genes conferring apomixis development would greatly facilitate the transfer of this trait to wide variety of crops. Such studies are now in progress.

• Journal of Plant Biotechnology
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• v.40 no.1
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• pp.37-42
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• 2013

Rice is one of the most important cereal crops as a model plant for functional genomics of monocotyledons and usually transformed using Agrobacterium tumefaciens. However, the transformation's process using previous method is still time consuming and uneconomical, low efficiency. In this study, we established a new method by modifying the general Agrobacterium protocol especially in the infection and co-cultivation, Agrobacterium elimination, infected calli's selection steps using liquid media. We directly inoculated Agrobacterium containing a ZjLsL gene under the control of constitutive promoter into the 1- to 3-week-old rice calli derived from mature seeds. After 3 days of co-cultivation, the infected calli were transferred onto liquid media of Agrobacterium elimination and calli's selection for 3 days. The calli were transferred to calli's growth solid media for 14 days and then the calli transferred to shoot induction and root induction media. Putative transformants were initially selected on the medium containing phosphinothricin, and the PAT protein verified by PAT strip test. This method in this study would lead to reduction of substantial labor and time to generate transgenic plants.

• Journal of Veterinary Clinics
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• v.25 no.2
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• pp.131-135
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• 2008

A 5-year-old Chihuahua dog was evaluated for a tetraparesis. The dog was presented with a non-ambulatory tetraparesis and neck pain. Radiography demonstrated an atlantoaxial (AA) subluxation and increased distance between the dorsal arch of the C1 and the dorsal spinous process of the C2. The AA joint was fixed with ventral transarticular fixation using two screws under fluoroscopic guidance. Neck brace was applied during 3 weeks post-operation. After 4 weeks, the dog was fully ambulatory with improved neurological function. Postoperative radiographs confirmed reduction of the luxation and no migration of screws. The dog showed complete resolution of clinical signs without signs of recurrence till 4 months after operation. Proper angulations of screws provided under fluoroscopic guidance, enabled adequate stabilization of the AA joints using ventral transarticular screw fixation which improved neurologic outcome of the patient.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.211-211
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• 1999

Titanium nitride (TiN) thin films have useful properties including high hardness, good electrical conductivity, high melting point, and chemical inertness. The applications have included wear-resistant hard coatings on machine tools and bearings, decorative coating making use of the golden color, thermal control coatings for widows, and erosion resistant coatings for spacecraft plasma probes. For all these applications as feature sizes shrink and aspect ratios grow, the issue of good step coverage becomes increasingly important. It is therefore essential to manufacture conformal coatings of TiN. The growth of TiN thin films by chemical vapor deposition (CVD) is of great interest for achieving conformal deposition. The most widely used precursor for TiN is TiCl4 and NH3. However, chlorine impurity in the as-grown films and relatively high deposition temperature (>$600^{\circ}C$) are considered major drawbacks from actual device fabrication. To overcome these problems, recently, MOCVD processes including plasma assisted have been suggested. In this study, therefore, we have doposited Ti(C, N) thin films on Si(100) and D2 steel substrates in the temperature range of 150-30$0^{\circ}C$ using tetrakis diethylamido titanium (TDEAT) and titanium isopropoxide (TIP) by pulsed DC plamsa enhanced metal-organic chemical vapor deposition (PEMOCVD) method. Polycrystalline Ti(C, N) thin films were successfully grown on either D2 steel or Si(100) surfaces at temperature as low as 15$0^{\circ}C$. Compositions of the as-grown films were determined with XPS and RBS. From XPS analysis, thin films of Ti(C, N) with low oxygen concentration were obtained. RBS data were also confirmed the changes of stoichiometry and microhardness of our films. Radical formation and ionization behaviors in plasma are analyzed by optical emission spectroscopy (OES) at various pulsed bias and gases conditions. H2 and He+H2 gases are used as carrier gases to compare plasma parameter and the effect of N2 and NH3 gases as reactive gas is also evaluated in reduction of C content of the films. In this study, we fond that He and H2 mixture gas is very effective in enhancing ionization of radicals, especially N resulting is high hardness. The higher hardness of film is obtained to be ca. 1700 HK 0.01 but it depends on gas species and bias voltage. The proper process is evident for H and N2 gas atmosphere and bias voltage of 600V. However, NH3 gas highly reduces formation of CN radical, thereby decreasing C content of Ti(C, N) thin films in a great deal. Compared to PVD TiN films, the Ti(C, N) film grown by PEMOCVD has very good conformability; the step coverage exceeds 85% with an aspect ratio of more than 3.

• Journal of Science and Technology Studies
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• v.15 no.1
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• pp.181-214
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• 2015

This study analyzed the characteristics of the politics of technoscience and governance in South Korea, taking advantage of the policy changes on the stem cell research after Hwang's affair. In spite of generally accepted conventional wisdom that stem cell research had been suffering 'crisis' after the Hwang's affair, South Korea succeeded in developing the first and the largest stem cell product in the world. However, considering the fact that the stem cell research capabilities and technological competitiveness of Korea have been assessed as relatively low compared to the development performance, there is a need to extrapolate how such result could be achieved. To answer these questions, we analyzed changes in the R&D expenditure before and after the scandal and verified the 'crisis of stem cell research' following the reduction of financial support from government. From the analysis of literature on the policy reports and news, we described the process of discourse changes in policy and analyzed the characteristics of the politics of technoscience and governance of stem cell research. This study emphasized that the government R&D and regulation policy play the key roles in the development of stem cell research rather than in the technological competitiveness in South Korea. Furthermore, this study argued that democratic governance still does not work under the policy conditions that technocratic decision-making of stem cell research fails to learn from the Hwang's affairs.

• Korean Journal of Social Welfare
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• v.37
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• pp.381-405
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• 1999

The primary purpose of this study is to design and perform juvenile group program and. to evaluate the effectiveness of that program The group was consisted of 10 fourth-grade elementary school boys who have had such factors that might force themselves to be delinquent, for example, broken family, having delinquent siblings or friends, family violence, and etc. The group had been held once a week and continued for 5 months. The effectiveness of that program is evaluated quantitatively and qualitatively through goal-attainment model. The ultimate goal of this program is reduction of delinquency stimulating factors which are operationalized with overall self-esteem - family related self-esteem, friend related self-esteem, and school related self-esteem. Quantitative evaluation is performed by pre- and post-test with Hare Self-Esteem Scale. Case records, family records, group activities records, and reports from schools are analyzed for the qualitative evaluation. According to paired samples t-test scores, average overall self-esteem scores of experimental group members were escalated from 67.57 to 74.86, and this difference between pre-test and post-test was statistically significant. Difference of experimental group was bigger and more striking than that of control group. These results suggest that designed and performed group program in this study would be effective in preventing juvenile from being delinquent.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.32.1-32.1
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• 2017

To dynamically and chemically understand how filaments, dense cores, and stars form under different environments, we are conducting a systematic mapping survey of nearby molecular clouds using the TRAO 14 m telescope with high ($N_2H^+$ 1-0, $HCO^+$ 1-0, SO 32-21, and $NH_2D$ v=1-0) and low ($^{13}CO$ 1-0, $C^{18}O$ 1-0) density tracers. The goals of this survey are to obtain the velocity distribution of low dense filaments and their dense cores for the study of their origin of the formation, to understand whether the dense cores form from any radial accretion or inward motions toward dense cores from their surrounding filaments, and to study the chemical differentiation of the filaments and the dense cores. Until Feb. 2017, the real OTF observation time is 460 hours. We have almost completed mapping observation with four molecular lines ($^{13}CO$ 1-0, $C^{18}O$ 1-0, $N_2H^+$ 1-0, and $HCO^+$ 1-0) on the five regions of molecular clouds (L1251 of Cepheus, Perseus west, Polaris south, BISTRO region of Serpense, California, and Orion B). The maps of a total area of $7.38deg^2$ for both $^{13}CO$ and $C^{18}O$ lines and $2.19deg^2$ for both $N_2H^+$ and $HCO^+$ lines were obtained. All OTF data were regridded to a cell size of 22 by 22 arcseconds. The $^{13}CO$ and $C^{18}O$ data show the RMS noise level of about 0.22 K and $N_2H^+$ and $HCO^+$ data show about 0.14 K at the velocity resolution of 0.06 km/s. Additional observations will be made on some regions that have not reached the noise level for analysis. We are refining the process for a massive amount of data and the data reduction and analysis are underway. This presentation introduces the overall progress from observations to data processing and the initial analysis results to date.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.228-236
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• 2009

In this study, we investigated morphological characteristics of $SF_6$ clathrate hydrate crystals to understand its formation and growth mechanism. $SF_6$ clathrate hydrate crystals were formed in high-pressure reaction cell charged with pure water and $SF_6$ gas at constant pressure and temperature. Two-phase ($SF_6$ gas/aqueous solution) and three-phase ($SF_6$ gas/aqueous solution/$SF_6$ liquid) conditions were investigated, In both conditions, dendritic shape hydrate crystals were grown as like fibriform crystals along upward growth direction at the gas/aqueous solution interface. In the case of the reaction process of three-phase condition, when the $SF_6$ gas bubbles which were generated in $SF_6$ liquid phase due to the reduction of reaction cell pressure stuck to the gas/aqueous interfaces, the hydrate phase were appeared at the surface of the bubbles. This paper presents the detail growth characteristics of $SF_6$ hydrate crystals including crystal nucleation, migration, growth and interference.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.6
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• pp.447-458
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• 2003

A high speed multiplier is essential basic building block for digital signal processors today. Typically iterative algorithms in Signal processing applications are realized which need a large number of multiply, add and accumulate operations. This paper describes a macro block of a parallel structured multiplier which has adopted a 32$\times$32-b regularly structured tree (RST). To improve the speed of the tree part, modified partial product generation method has been devised at architecture level. This reduces the 4 levels of compression stage to 3 levels, and propagation delay in Wallace tree structure by utilizing 4-2 compressor as well. Furthermore, this enables tree part to be combined with four modular block to construct a CSA tree (carry save adder tree). Therefore, combined with four modular block to construct a CSA tree (carry save adder tree). Therefore, multiplier architecture can be regularly laid out with same modules composed of Booth selectors, compressors and Modified Partial Product Generators (MPPG). At the circuit level new Booth selector with less transistors and encoder are proposed. The reduction in the number of transistors in Booth selector has a greater impact on the total transistor count. The transistor count of designed selector is 9 using PTL(Pass Transistor Logic). This reduces the transistor count by 50% as compared with that of the conventional one. The designed multiplier in 0.25${\mu}{\textrm}{m}$ technology, 2.5V, 1-poly and 5-metal CMOS process is simulated by Hspice and Epic. Delay is 4.2㎱ and average power consumes 1.81㎽/MHz. This result is far better than conventional multiplier with equal or better than the best one published.