• 환경생물
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• 제18권2호
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• pp.279-290
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• 2000

조하대 각 정점에서 중형저서동물의 그룹별 조성을 보면 총 22개의 그룹이 출현하였다. 배수갑문 바로 앞의 정점에서는 방류 하루 후, 방류 일주일 후가 방류 하루 전에 비해 중형저서동물군집의 각 개체군의 개체수가 다른 정점에 비해 현저하게 감소함을 나타냈다. 우점하고 있는 분류군은 방류 하루 전에는 저서성 요각류가 가장 우점하고 있었고, 방류 하루 후에는 거의 출현하지 않는 현상을 보였다. 배수 갑문으로부터 약간 떨어진 정점에서는 앞의 정점과 같이 급격한 감소를 보이지는 않았지만 개체수가 서서히 감소하고 있음을 나타냈다. 이 정점에서는 모든 시기에 있어 항상 선충류가 가장 우점하고 있었고, 그 다음으로 저서성 요각류와 유공충류가 서로 번갈아 가며 우점하고 있음을 보였다. 배수갑문으로부터 가장 멀리 떨어진 정점에서는 방류 후에도 전체적으로 그 개체수 값은 떨어지지 않음을 보여준다. 수직분포를 보면 배수갑문 앞 정점에서는 전 시기에 있어서 저서성 요각류는 표층 0-1cm에 가장 많이 분포하고 있었다. 저서성 요각류는 퇴적물의 심도가 깊어질수록 급격한 감소를 보이고 전반적으로 퇴적물 내 2cm이하의 층에서는 거의 출현을 하지 않았다. 층 개체수를 보면 방류 전에는 표층 0-lcm에서 가장 높은 서식밀도를 보이고 심도가 증가함에 따라 개체수가 감소함을 나타내었으나, 방류 후에는 균일하지 않은 양상을 보여준다. 또한 방류 전에는 표층에 저서성 요각류가 400개체/10$\textrm{cm}^2$ 이상 우점하고 있었지만 방류 후에는 거의 출현하고 있지 않음을 나타내었다. N/C비는 정점 4에서 방류 하루 전 0.7의 아주 낮은 값에서 방류 하루 후 약 30배에 달하는 19.0의 높은 값을 나타냈다. 이에 비하여 정점 6과 7에 있어서는 방류 하루 후에는 오히려 약간의 감소를 보이다가 방류 일주일 후 아주 높은 값을 보였다. 조간대 방아머리 갯벌의 경우는 정점 1에서만 일반적인 값을 보이고, 정점 2에서 아주 높은 값인 191.3을 나타냈다. 결론적으로 시화호 방류수는 중형저서동물군집에 직접적이며 상대적으로 아주 짧은 시간에 영향을 미치는 것으로 나타났으며, 이러한 특징은 중형저서동물이 장ㆍ단기적인 오염의 영향을 파악하기에 아주 유효한 대상 생물임을 시사한다.

• Molecular & Cellular Toxicology
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• 제3권4호
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• pp.314-319
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• 2007

The effects of common variants of CYP1A2 gene (CYP1A2$^*$1C and CYP1A2$^*$1F) on the CYP1A2 activity and inducibility were controversial. The aim of the present study is to investigate the effects of CYP1A2$^*$1C and CYP1A2$^*$1F on the activity of CYP1A2 determined by urinary caffeine metabolite ratio in Koreans. As might be expected, there was large inter-individual variation (16-folds) of CYP1A2 activity ranged from 2.41 to 39.58. The mean CYP1A2 activity of smokers was significantly higher than that of non-smokers. The frequencies of CYP1A2$^*$1C (-3858A) and $^*$1F (-164A) alleles were 0.219 and 0.646, respectively. The effect of CYP1A2$^*$1C on the CYP1A2 activity was not significant. However, the CYP1A2 activity of subjects with AA genotype for CYP1A2$^*$1F allele was significantly lower than that of non-AA genotypes (CC, or CA). Interestingly, the significant effect of CYP1A2$^*$1F allele on CYP1A2 activity was not observed in nonsmokers. Our results suggest that CYP1A2$^*$1F allele rather than CYP1A2$^*$1C allele significantly influences on the inducibility of CYP1A2 in Koreans. Owing to small sample size of our study, further studies should be conducted to reveal the inter-ethnic difference or the gene-environmental interaction.

• 한국산학기술학회논문지
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• 제12권4호
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• pp.1654-1662
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• 2011

본 연구의 목적은 $\"{O}$.Arslan et al.(2006)의 연구방법론을 적용하여 국내 기업의 현금보유(cash holdings)가 투자-현금흐름 민감도(investment-cash flow sensitivity)에 어떤 영향을 주는지를 분석하는 데 있다. 1981년부터 2009년까지 외환위기 이전과 이후 그리고 외환위기 기간으로 분류하여 각 기간별로 현금보유가 투자-현금흐름 민감도에 어떤 영향을 주는 지를 비교 분석하였다. 연구 결과는 다음과 같다. 첫째, 전체 기업을 재무적 제약(financial constraint) 에 대한 고려 없이 3개의 기간으로 분류해서 살펴본 결과 외환위기 기간을 제외한 외환위기 이전과 이후 기간에서는 현금보유가 많은 기업일수록 투자-현금흐름 민감도는 감소하였다. 둘째, 기업규모나 배당지급 기준에 의해 재무적 제약하에 있지 않은 기업으로 분류된 경우에는 현금보유가 많을수록 투자-현금흐름 민감도는 오히려 증가하는 것으로 나타났다. 이는 $\"{O}$.Arslan et al.(2006)의 연구와 일치하지 않는 결과인데 첫째, 기업규모나 배당지급 여부는 국내에서는 기업의 재무적 제약을 나타내는 기준으로 불완전하며 둘째, 본 연구에서 고려하지 못한 투자-현금흐름 민감도에 영향을 주는 다른 요인들이 존재할 수 있기 때문이다. 하지만 현금보유기준에 의해 재무적 제약하의 기업으로 분류된 경우에는 투자-현금흐름 민감도는 낮게 나타났다. 이는 $\"{O}$.Arslan et al.(2006)의 연구결과와 일치한다. 끝으로 전체 기간 동안 현금보유 결정요인은 다음과 같다. 현금흐름(cash flow)과 시장가/장부가비율(market to book ratio)은 증가할수록, 단기부채와 투자지출 그리고 기업규모는 감소할수록, 기업의 현금보유증가에 양(+)의 영향을 주는 것으로 나타났다.

• 한국지반공학회논문집
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• 제22권10호
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• pp.77-91
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• 2006

국내 숏크리트 관련 기술들은 지금까지 많은 발전을 이루어 왔으나 재료, 시공 및 관련 품질규격 등에서 여전히 문제들을 가지고 있다. 국외의 경우 $39.2{\sim}58.8 MPa$에 이르는 고강도 숏크리트 시공이 가능하여 터널에서 2차 라이닝의 대체나 장기내구성의 확보가 충분히 가능한 반면, 국내의 경우 설계강도가 20.6MPa 내외로 낮은 편이며 장기내구성도 신뢰하지 못하고 있는 실정이다. 본 연구에서는 국내 숏크리트의 강도 증진을 위해 고품질 혼화재와 고성능 급결제를 적용한 현장실험을 실시하였고, 유럽통합규격(EFNARC)에 의거하여 품질평가를 수행하였다. 또한, 탄산화와 동결융해의 복합인자에 의한 열화시험을 수행하여 고강도 숏크리트의 장기내구성을 평가하였다. 실험결과 알칼리 프리계 급결제를 사용한 경우 초기강도 증진율이 $90{\sim}97%$로 가장 높게 나타났고, 실리카 흄을 혼입한 숏크리트의 압축강도는 $45.2{\sim}55.8MPa$, 휨강도는 $5.01{\sim}6.66MPa$로 혼입하지 않은 경우에 비해 각각 $37{\sim}79%$, $17{\sim}61%$의 강도 증진 효과가 나타났다. 또한, 실리카 흄 치환율이 $7.5{\sim}10%$일 때 강도증진 효과가 가장 우수한 것으로 나타났다. 특히, 실리카 흄의 치환은 강섬유 혼입에 의한 숏크리트의 열화현상을 최소한으로 감소시켜, 숏크리트의 장기내구성을 확보하는데 효과가 있음을 알 수 있었다.

• 대한치과보철학회지
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• 제42권6호
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• pp.664-670
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• 2004

Statement of problem. One of the common problems of dental implant prosthesis is the loosening of the screw that connects each component, and this problem is more common in single implant-supported prostheses with external connection. Purpose. The purpose of this study was to examine the changes of detorque values of abutment screws with external connection in different abutment heights. Materials and methods. After cyclic loading on three different abutment heights, detorque values were measured. Abutments were retained with titanium abutment screws tightened to 30 Ncm (30.5 kgmm) with digital torque gauge as recommended by the manufacturer. Replacing abutments, implants and titanium abutment screws with new ones at every measurement, initial detorque values were measured six times. In measuring de torque values after cyclic loading, Avana Cemented Abutments of 4.0 mm collar, 7.0 mm height (Osstem Co., Ltd., Seoul, Korea) were used with three different lengths of 5.0, 8.0, 11.0 mm. Shorter abutments were made by milling of 11.0 mm abutment to have the same force-exercised area of 4.5 mm diameter. Sine curve force (20N-320N, 14Hz) was applied, and detorque values were measured after cyclic loading of 2 million times by loading machine. Detorque values of initial and after-loading were measured by digital torque gauge. One-way ANOVA was employed to see if there was any influence from different abutment heights. Results. The results were as follows: 1. The initial detorque value was 27.8$\pm$0.93 kgmm, and the ratio of the initial detorque value to the tightening torque was 0.91(27.8/30.5). 2. Measured detorque values after cyclic loading were declined as the height of the abutment increased, that was, 5.0 mm; 22.3$\pm$0.82 kgmm, 8.0 mm; 21.8$\pm$0.93 kgmm, and 11.0 mm; 21.3$\pm$0.94 kgmm. 3. One-way ANOVA showed no statistically significant differences among these (p>0.05). 4. Noticeable mobility at the implant-abutment interface was not observed in any case after cyclic loading at all.

• 대한두경부종양학회지
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• 제13권2호
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• pp.221-227
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• 1997

The authors reviewed 106 cases of parotid gland tumor at Presbyterian Medical Center seen during the past 10 years between January, 1986 and December, 1995. The results were obtained as follows; 1) 86 cases(81.1%) were benign tumors and 20 cases(18.9%) were malignant tumors. 2) Overall male and female sex ratio was 1 : 1.4. 3) For benign tumors, the mean age was 47.9 and for malignant tumors, the mean age was 43.4. 4) Clinical manifestations in benign tumors were palpable mass in 86 cases(100%), pain in 6 cases(6.9%), facial nerve palsy in 2 cases(2.3%), lymphadenopathy in 1 case(1.2%); and in malignant tumors, palpable mass in 20 cases(100%), pain in 7 cases(35%), facial nerve palsy in 2 cases(10%) and lymphadenopathy in 3 cases(15%). Thus, the presence of pain, facial nerve palsy and lymphadenopathy suggest malignant tumors. 5) Operative procedures in benign tumors included superficial parotidectomy in 53 cases(61.6%), total parotidectomy in 10 cases(11.6%), local excision in 23 cases(26.7%); and in malignant tumors, superficial parotidectomy in 3 cases, total parotidectomy in 1 case, local excision in 1 case, superficial parotidectomy with supraomohyoid neck dissection in 6 cases, total parotidectomy with supraomohyoid neck dissection in 8 cases, total parotidectomy with radical neck dissection in 1 case. 6) Postoperative complications in benign tumors were transient facial nerve palsy in 14 cases, Frey's syndrome in 2 cases. In malignant tumors complications included transient facial nerve palsy in 3 cases and permanent facial nerve palsy in 1 case. 7) Pleomorphic adenoma was the most common benign parotid tumor and mucoepidermoid carcinoma was the most common malignant tumor. 8) In our review of 20 patients with malignant parotid tumors, all patients who received supraomohyoid neck dissection and postoperative radiation therapy remain alive from 1986 to 1995 years. Two deaths in this series were adenoid cystic carcinoma patients who failed to receive postoperative radiation therapy. These series of cases have been studied in order to determine whether supraomohyoid neck dissection and postoperative radiation therapy may have further therapeutic effect.

• 치과방사선
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• 제26권2호
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• pp.133-145
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• 1996

Aspirating or swallowing foreign bodies is a common occurrence. If they are wholly or partly radiopaque, their localization in and progress through the gastrointestinal tract can be more effective. Of the dental origin foreign materials swallowed, the most common things are fragments of anterior maxillary partial denture. But the radiopacity of denture base resins is not sufficient to determine the location of the objects. The purpose of this study was to develop a radiopaque dental acrylic resin, which has clinically detectible radiopacity with minimal change of mechanical properties and color. The radiopacity, color change(CIE 6..E) and microhardness of acrylic resins were determined after mixing barium sulfate or iodide compound. Thermocycling course was conducted to determine the change of characteristic of resins after using for a long time in the mouth. Five or ten percent of barium sulfate to total weight of cured material was mixed with heat curing dental acrylic resin or chemically curing orthodontic resin. In the case of iodide compound, the mixing ratio was two or three percent. After mixing the high radiopaque materials, resin was cured to 20×20×2 mm plate, polished with #600 sand paper and finally polished with Microcloth(Buehler). The specimens were thermocycled in 5 and 55 t distilled water for 2,000 times, and the measurement of radiopacity, color and Vickers hardness was repeated every 500 times thcrmocycling. The radiopacity of specimens on the X -ray films was measured with densitometer(X-rite). The color change was detennined with differential colorimeter(Model TC-6FX, Tokyo Denshoku), and the Vickers hardness number was measured with microhardness tester(Mitsuzawa). The following results were obtained : 1. All the three variables, the kinds of acrylic resins, the mixing or the kinds of high radiopaque materials and thermocycling, had combined effect on the radiopacity of the dental acrylic resins(p<0.0l). 2. The two variables, the mixing or the kinds of high radiopaque materials and thermocycling, influenced on the radiopacity of the dental acrylic resins(p<0.01). But the kinds of acrylic resins did not influence on the color change of mixed dental acrylic resins(p>0.05). 3. Each of the three variables, the kinds of acrylic resins, the mixing or the kinds of high radiopaque materials and thermocycling, influenced on the radiopacity of dental acrylic resins(p<0.0l). 4. The high radiopaque materials used in this study did not yield clinically usable radiopacity, and the color change was great after mixing those materials.

• 한국토양비료학회지
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• 제33권1호
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• pp.8-14
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• 2000

암모늄태질소를 질소의 급원으로 공급하기 위하여 요소와 유안을 질소조성물로 하여 2대1로 혼합한 후 다시 점결제 및 확산완충계와 혼합하여 비커형태의 용기안에 충진하여 제조된 시제품인 $NH_4$-Beaker Deeposit비료를 토마토유묘의 정식기에 유묘의 밑으로 1회 국지사용하여 토마토에 대한 생육 및 수량과 질소공급 효과를 일반 시비방법인 $NH_4NO_3$를 3회 전층 분배시용한 관행의 대구조와 비교하였다. 1년차 시험에서 질소의 용출을 조절하기 위하여 유안과 요소를 2:1로 혼합한 질소조성물에 7.5 g의 석고를 점결제로 사용하였을 때 토마토과실 수량은 1주당 6345 g으로 관행의 대조구의 수량인 5865 g보다 증수되었다. 토마토과실과 경엽의 총 질소흡수량 또한 7.5 g의 석고를 점결제로 사용한 $NH_4$-Beaker Deposit비료 시용구에서 8997 mg으로 관행의 7215 mg보다 통계적 유의성이 있었다. 2년차 시험에서는 C/N율이 10인 퇴비를 확산완충제로 비커에 충진한 시험구 5를 제외한 모든 $NH_4$-Beaker Deposit비료의 시용구에서의 질소흡수량이 높았다. 질소의 용출을 조절하기 위하여 7.5 g의 석고를 비커안에 충진하고, 그 윗부분으로 질소의 확산기울기를 조절하기 위하여 점질토양을 확산 완충제로 충진한 처리구에서의 토마토과실의 질소흡수량은 주당 8646 mg으로 가장 높았으며 관행의 대조구와 통계적인 유의성이 있었다. 토마토작물의 뿌리분포를 조사한 결과 확산완충제로 점질토양, C/N율이 16인 퇴비를 사용한 처리구의 경우 뿌리가 비커로 집중분포 되는 경향을 나타냈으며 굴지성에 반하여 비커안으로 자라는 현상을 나타냈다. 토마토 수량 및 질소흡수량을 고려할 때 7.5 g의 석고를 점결제로 사용하고, C/N율이 16인 부엽퇴비 및 점질토양을 확산완충제로 비커에 충진하여 제조한 시제품이 가장 좋은 처리로 판단되었다.

• Journal of Korean Dental Science
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• 제5권2호
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• pp.68-76
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• 2012

Purpose: The headache is a symptom that various somatic or non-somatic disorders gives an effect to head and neck system. The neck and the shoulder pain is a common muscle pain that can not control and bothers the patient after chronic state. The headache and the neck and the shoulder muscle pain are treated with various conventional treatment methods. But, there are cases that symptoms did not resolve or increased in some clinical cases. And generally, the result of temporomandibular disorders (TMD) treatment is good. But, despite of a normal treatment was performed for TMD, there are cases that TMD symptoms did not resolved in clinical cases. In template clinic of Soonchunhyang University Bucheon Hospital, co-operative neurophysiologic treatment of Department of Neurosurgery and Dentistry are done for patients, who had head and neck pain or atypical symptoms that did not treated with various conventional treatment method such as surgery or medication etc. Materials and Methods: Four hundred fifty one patients who have treated in the template clinic, Soonchunhyang University Bucheon Hospital, from January of 2006 to December of 2008 were subjected in this study. Result: Overall average age was 31.9 years old. Ratio of numbers is 74.3% in female and 25.7% in male. The success rate of treatment in TMD symptom was 89.9%, in headache was 88.8%, in muscle pain was 81.6%. Statistically significance of differences visual analogue scale evaluation between before and after had been treated patients who have over average grade headache was calculated by paired t-test. P<0.05 was considered significant. Conclusion: We suggest the template appliance can be attempted for cases whose headache, the neck and the shoulder muscle pain and TMD are not resolved with various conventional treatment methods.

• International Journal of Fluid Machinery and Systems
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• 제4권4호
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• pp.367-374
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• 2011

Water hammer pumps can effectively use the water hammer phenomenon in long-distance pipeline networks that include pumps and allow fluid transport without drive sources, such as electric motors. The results of experiments that examined the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. In addition, a paper has also been published analyzing the water hammer phenomenon numerically by using the characteristic curve method for comparison with experimental results. However, these conventional studies have not fully evaluated the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. Therefore, as a first stage for the understanding of water hammer pump performance in comparison with the characteristics of typical turbo pumps, the previous paper experimentally examined how the hydrodynamic characteristics were affected by the inner diameter ratio of the drive and lifting pipes, the form of the air chamber, and the angle of the drive pipe. To understand the behavior of the components attached to the valve chamber and the air chamber that affects the performance of water hammer pumps, the previous study also determined the relationship between the water hammer pump performance and temporal changes in valve chamber and air chamber pressures according to the air chamber capacity. For the geometry of components attached to the drain valve, which is another major component of water hammer pumps, this study experimentally examines how the water hammer pump performance is affected by the length of the spring and the angle of the drain pipe.