리이더쉽 類型과 組織有效性 간의 關係에 대한 實證的 硏究

정근식 釜山大學校 1989 국내석사

고전압 전기장을 이용한 하수처리장 방류수 중의 대장균군 소독에 관한 연구

정근식 濟州大學校 産業大學院 2004 국내석사

Using high voltage electric fields induced by high voltage AC(10-12 kV/cm, 20 kHz) and pulsed electric field generator(20-30 kV/cm, 40 Hz) as a semipermant and environment-friendly disinfecting apparatus, the disinfection effect of coliform group in the effluent of sewage plant was investigated. The effects of electric field strength, treatment time, discharge area of a discharge tube, water quality factors(electric conductivity, pH and SS) on its death rate were examined. The results obtained were summarized as follows. 1. It was found that the death rate of coliform group was increased with increasing electric field strength, its logarithmic survival fraction was decreased linearly with increasing electric field strength at a constant treatment time, the critical AC and pulsed electric field strength by extrapolation was 5 kV/cm and 2 kV/cm, respectively, and its death rate constant was increased greatly with increasing treatment time. 2. It was found that the death rate of coliform group was increased with increasing treatment time, its logarithmic survival fraction was decreased linearly with increasing treatment time at a constant electric field strength, the critical treatment time of AC and pulsed electric field strength by extrapolation was 5 min and 2 min, respectively, regardless of electric field strength, and its death rate constant was increased greatly with increasing electric field strength. 3. Comparing the death rate of coliform group by AC and pulsed electric fields used in this study, its death rate was higher for the latter than the former, but did not increase linearly with increasing electric field strength, which is considered to be caused by the difference of frequency and pulse width. 4. The results obtained for the effects of discharge area, electric conductivity and pH on the death rate of coliform group using AC electric field(12 kV/cm, 20 kHz) were as follows: its death rate showed the trend to increase linearly with increasing discharge area; for the effect of electric conductivity, its death rate was increased with increasing electric conductivity, regardless of ionic species, increased with increasing cationic valency, and was similar between the same cationic valency; the pH 5-9 used in this study did not affect its death rate; its death rate was decreased with increasing SS concentration. 5. It is considered that the electric field eqipment to generate a strong high voltage electric field and to be able to increase the width and number of the pulse is necessary, in order to apply it to disinfection process of effluent in the sewage plant practically.

폴리카프로락톤 실리카 나노 복합체를 이용한 골이식대체재 개발에 관한 연구

정근식 단국대학교 대학원 2003 국내박사

적절한 골이식재의 요구조건으로는 체내에서 신생골 형성을 유도하는 생체활성을 가지며 골결손 부위가 신생 자가골에 의하여 대체될 때가지 유지하다가 흡수되어 잔존하지 않는 것이다. 이러한 요구조건을 만족시킬만한 골이식재를 개발하고자 체액과 반응하여 저결정성 탄산 아파타이트를 형성하는 실리카와 생분해성을 갖는 고분자를 결합하여 복합체를 제작하고 이의 생물학적 안전성과 골형성능을 시험하였다. 봉합사등에 사용되어 온 폴리카프로락톤과 생체활성 유리 제작에 사용된 실리카를 이용하여 나노복합체를 제작하고 이의 생체활성을 평가하기 위하여 의사체액 내에서 저결정성 탄산 아파타이트가 형성되는 것을 확인한 후 몇가지 조성으로 제작하여 본실험에 사용하였다. 식품의약품 안전청에서 제시하는 의료용구의 생물학적 안전에 관한 공통 기준 규격에 의거하여 폴리카프로락톤/실리카 나노복합체의 안전성실험을 시행하였다. 시험 항목으로는 급성, 아급성 독성 시험, 감작시험, 배양세포증식저해시험, 무균시험. 등을 시행하였고 골이식재로 사용함에 있어서 골을 형성하는 주세포인 골모세포의 활성을 측정하기위하여 시험관 내에서 골모세포의 부착시험, 골모세포의 증식시험, 골모세포의 유전자 발현 시험.등을 시행하였다. 또한 이 골이식재의 효능을 검사하기위하여 가토 두개골에 이식하고 8주 후에 골형성 정도와 재료의 흡수 정도를 현미경적 수준에서 관찰하였다. 그 결과 급성, 아급성 독성이 나타나지 않았으며 intradermal induction phase와 topical induction phase 및 challenge phase에서 감작반응이 나타나지 않았다. 배양세포 증식 저해시험으로 세포증식을 저해하지 않을 뿐만 아니라 오히려 약간의 세포증식 촉진 효과가 있는 것으로 추정되었다. 무균시험 결과는 검액을 배양한 후 배지성능시험용 시험관을 제외한 모든 시험관에서 균이 발육되지 않았다. 골모세포 부착시험과 증식 시험 결과 시간이 지날수록 골모세포의 부착 및 증식효과가 뛰어난 재료임을 알 수 있었다. 세포분화 유전자 발현 시험을 시행한 결과 세포분화 관련 유전자인 cbfa1 및 초기분화표지인자인 염기성인산분해효소(alkaline phosphatase)와 후기분화표지인자인 osteocalcin 및 참조유전자인 GAPDH에 대한 mRNA 분석을 배양접시표면에서 RT-PCR로 확인하였다. 폴리카프로락톤/실리카 나노복합체의 골형성능 시험결과 재료의 조성비에 따라서 골형성 양상이 상이하였으나 실험군 #218을 제외하고는 염증반응을 보이지 않으면서 신생골 형성이 잘 이루어졌다. 또한 일부 재료는 8주 소견에서 흡수되는 양상을 관찰할 수 있었다. 이상과 같은 연구 결과들을 종합하여 폴리카프로락톤과 실리카 나노복합체는 생물학적 안전성이 확인되었으며 효능적으로 골모세포의 활성을 촉진시키고 신생골 형성을 증진시키는 재료이므로 생체활성과 생분해성을 갖는 새로운 골이식대체재 개발이 가능한 것으로 사료되었다. A bioactive and degradable poly(epsilon -caprolactone)/silica nanohybrid(PSH) was synthesized for the application as a bone substitute. PSH was manufactured by using silica and polycaprolacton. PSH was manufactured in some composition after low crystaline apatite had been formed in simulated body fluid and, was used this study. The safety of the PSH was established by test of acute, and subacute toxicity, sensitization cytotoxicity and sterility. In order to assess activity of osteoblast, the test for attaching osteoblast, proliferation test for osteoblast, differentiating gene expression test are performed in vitro. And bone substitutes were grafted in rabbit's calvarium, during 8 weeks for testing efficacy of bone substitutes. Degree of osteogenesis and absorption of substitutes were evaluated in microscopic level. In result, it was not appeared that acute and subacute toxicity, sensitization in intradermal induction phase, topical induction phase and challenge phase. It was shown that the test can not inhibit cell proliferation. adversely, it had some ability to accelerate cell proliferation. The result of sterility test described bacterial growth was not detected in most test tube. The attaching and proliferation test of osteoblast had good results. In the result of differentiating gene expression test for osteoblast, cbfa1 and, alkaline phosphatase, osteocalcin and GAPDH were detected with mRNA analysis. In the PSH bone formation test, ostgeoblastic activity would be different as material constitution but it had good new bone formation ability except group #218. futhermore, some material had been absorbed within 8 weeks. Above studies, PSH had bio-compatibility with human body, new bone formation ability and accelerate osteoblastic activity. So it would be the efficient bone substitute material with bio-active and biodegradable.

하악 부분 무치악 환자의 골유착성 임플랜트 주위 연조직에 관한 연구

정근식 단국대학교 대학원 1998 국내석사

헤겔에 있어서 社會와 國家의 性格에 관한 연구

정근식 서울大學校 大學院 1982 국내석사

주민운동의 구조와 역학에 관한 비교연구 : 1980년대 전남지역 개발 사례를 중심으로

정근식 서울대학교 대학원 1991 국내박사

벼 組織 培養에 關한 硏究

정근식 서울大學校 1975 국내박사

Evaluation of deposition samplers for polycyclic aromatic hydrocarbon monitoring

정근식 Graduate School of UNIST 2014 국내석사

Polycyclic aromatic hydrocarbons (PAHs) are an important environmental concern due to their carcinogenic and toxic properties. Moreover, several PAHs have been classified into mutagenic compounds. The sources of PAHs are classified into anthropogenic and natural sources such as incomplete combustion of fossil fuel, biomass burning, industrial boilers, and forest fires etc. Emitted PAHs can distribute both gaseous phase and particulate phase. As a large amount of PAHs emitted to the atmosphere is deposited to the land or sea, atmospheric deposition of PAHs is a significant phenomenon. There have been many studies of atmospheric deposition of PAHs, and several kinds of deposition samplers have been used. However, the results with different deposition samplers cannot be directly compared, because their performance was not fully compared or calibrated. Besides, the deposition fluxes and deposition velocities measured in the previous studies showed large variations even though the same samplers were used. Therefore, a through evaluation of different types of deposition samplers are required to clearly understand the process of atmospheric deposition of PAHs. In this study, various information on widely used deposition samplers (basic theories, structures, and advantages/disadvantages) was collected. Then, the performance of four types of deposition samplers was evaluated. In addition, a high volume air sampler was used to investigate the ambient levels of PAHs and deposition velocities. The samplers were deployed on the roof of the engineering building #2 in the Ulsan National Institute of Science and Technology (UNIST) from May 2013 to October 2013. Four types of deposition samplers (dry deposition sampler (DDP), velcro deposition sampler, resin deposition sampler, and bulk deposition sampler) were used. Particulate and gaseous PAHs were indivisually collected by a high volume air sampler once a week. The target compounds in this study were thirteen US-EPA priority PAHs except naphthalene, acenaphthene, and acynaphthylene. After sample extraction and clean up using silica gel columns, a gas chromatograph/mass spectrometer (GC/MS) was used for PAH qualification and quantification. In order to further interpretate the source-recepor relationship of PAHs, houly data of criteria air pollutants (CO, SO2, NO2, O3, and PM10) measured nearby UNIST was acquired from the Ulsan Institute of Health and Environment (UIHE). The ranges of SO2 were 1.3–9.9 ppb (Mean: 3.8 ppb) and 3.4–15.0 ppb (Mean: 6.8 ppb) in Samnam and Mugeo air pollution monitoring stations. The SO2 level showed seasonal variations related with fossil fuel consumption and wind direction. The level of SO2 in Mugeo was higher than that of Samnam because Mugeo is more influenced by vehicles and has more urban characteristics. The ranges of NO2 were 6.7–21.9 ppb (Mean: 12.6 ppb) in Samnam and 4.7–43.1 ppb (Mean: 24.0 ppb) in Mugeo. The ranges of O3 were 14.1–63.9 ppb (Mean: 34.0 ppb) in Samnam and 13.5–60.5 ppb (Mean: 27.4 ppb) in Mugeo. The ranges of PM10 were 15.1–57.1 μg/m3 (Mean: 30.9 μg/m3) in Samnam and 14.6–74.8 μg/m3 (Mean: 38.4 μg/m3) in Mugeo. The sampling site at UNIST was confirmed to be seasonally influenced by air pollution sources in Samnam and Mugeo according to geographical positions and major wind directions. The levels of gaseous PAHs were 1.10–7.02 ng/m3 (Mean: 4.23 ng/m3), and those of particulate PAHs were 0.85–2.82 ng/m3 (Mean: 1.67 ng/m3). Namely, the total PAH concentrations were 1.95–9.84 ng/m3 (Mean: 5.91 ng/m3) during the sampling period. The variation of PAH concentrations was not large, but they increased in spring and fall. The sampling site in this study is located in a rural area. Therefore, it was assumed that the sampling site was affected by criteria air pollutants and PAHs emitted from urban sources. Deposition fluxes and velocities of PAHs were calculated based on the amount of deposited PAHs and ambient air concentrations. The ranges of deposition fluxes of PAHs collected by DDP, velcro, resin, and bulk samplers were 4.55–15.13 μg/m2/d (Mean: 8.89 μg/m2/d), 13.14–30.92 μg/m2/d (Mean: 22.04 μg/m2/d), 7.72–55.41 μg/m2/d (Mean: 28.43 μg/m2/d), and 32.72–49.44 μg/m2/d (Mean: 40.13 μg/m2/d), respectively. This result indicates that deposition fluxes derived from different types of deposition samplers do not coincide and they should not be directly compared. DDP could not collect high molecular weight-PAHs mostly associated with fine particles. Therefore, the performance of the velcro sampler as a dry deposition sampler was better than that of DDP. As a bulk (dry/wet deposition) sampler, the performance of the Resin and bulk samplers was similar. On the basis of this result, further studies were suggested to improve the calculation of deposition fluxes and velocities.