• 한국환경보건학회지
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• 제48권2호
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• pp.86-95
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• 2022

Background: As high concentrations of uranium and radon have been detected in some areas in Korea, it is considered necessary to investigate natural radioactive materials in the Gwangju area. Objectives: This study aimed to identify the hydrochemical characteristics of groundwater in Gwangju and investigate the distribution characteristics of uranium and radon, which are naturally radioactive substances. Methods: To determine the uranium and radon concentrations in groundwater according to the geology of the Gwangju area, we measured 62 groundwater wells. A geological distribution map of uranium and radon content was prepared for this study. Results: The groundwater type, defined using a Piper diagram, was mainly Ca-HCO₃. The concentration of uranium in the groundwater ranged from 0 to 29.3 ㎍/L, with a mean of 3.3 ㎍/L and a median of 0.9 ㎍/L. The median concentration of uranium in groundwater was highest in alluvium, granitic gneiss, and biotite granite (classified by geological unit), in that order. The concentration of radon in the groundwater ranged from 4.8 to 313.2 Bq/L, with a mean of 75.6 Bq/L and a median of 59.6 Bq/L. The median concentration of radon in groundwater was highest in biotite granite, alluvium, and granitic gneiss, in that order. As a result of the correlation analysis of groundwater in the study area, there was no significant correlation between uranium and radon. Conclusions: In this study area, uranium was shown to be far below the concentrations allowed by drinking water quality standards, but radon concentrations exceeded drinking water quality monitoring standards in 11% of the samples. It was judged that appropriate measures, such as the installation of radon reduction facilities, will be required after a thorough review of high-concentration radon detection sites of in the research area.

• 한국가스학회지
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• 제22권3호
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• pp.84-90
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• 2018

정수장에서 염소 누출 사고 시 피해를 최소화하는 방안을 연구하였다. 장외영향평가의 위험도는 영향범위내 주민수와 사고 발생 빈도의 조합으로, 취급시설 운전온도, 긴급차단밸브 설치 위치 및 시설의 밀폐정도에 따른 피해범위 변화를 분석하여 피해범위 내 주민 수를 줄일 수 있는 최적의 조건을 제시하였다. 피해범위 산정은 KORA(Korea Off-site Risk Assessment Supporting Tool) 프로그램을 이용하였고, 운전온도가 낮아질수록, 용기의 브렌치 배관마다 긴급차단밸브가 설치될수록, 시설의 밀폐수준이 높을수록 피해범위가 감소하였다. 최악의 사고시나리오에서 감소율은 각각 17.6%, 71%, 34.5% 이며, 대안의 사고시나리오에는 각각 31.6%, 69.0%, 34.8% 이다.

• 대한치과보철학회지
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• 제36권2호
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• pp.258-272
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• 1998

This investigation evaluated patients who received Steri-Oss implants from the Dental Hospital of Chosun University during the period from March 1989 to August 1997. 346 fixtures of 127 patients were included in this study. The results were as follows ; 1.The follow-up period was defined as the period between the surgical placement of the implants and the last follow-up examination. The mean follow-up period was $2.17{\pm}1.21$ years. 2.The period between fixture installation and second surgery was $0.71{\pm}0.44$ years in the maxilla and $0.46{\pm}0.21$ years in the mandible. 3.The number of fixtures which were installed in the upper jaw(112) was less than that in the lower jaw(234) and in the posterior region(260) was more than in the anterior region(86). 4.The length of fixture which was most frequently used was 12 mm and least was 8mm. Screw implants were installed more than cylindrical implants. 3.8mm implant was the most common implans, followed by 4.5mm and 3.25mm. 5.The number of augmentation cases was more than that of non-augmentation cases and the rate of augmentation cases in the maxilla was more than that in the mandible. 6.Implant restorations for partial edentulos patients(94cases) were more than single- tooth implant restorations(33cases) or implant restorations for complete edentulos patients(10cases). 7.Free-standing prostheses for partially edentulous patients were more commom than any other type of connection between implants and natural teeth. 8.Plaque Index($0.95{\pm}0.74$) and Gingival Index($0.31{\pm}0.52$) were very similar around the natural teeth and reflected an acceptable level of plaque and gingivitis control. Mean value for keratinized mucosa index($1.93{\pm}1.20$) remained fairly constant around level 2(1-2 mm keratinized epithelium). 9.Patients were generally satisfied with implant in terms of comfort, function, speech and esthetics. 10.There was not a statistically significant differences in overall survial rate between implants placed in the maxilla (91.5%) and those placed in the mandible (93.8%). Fourteen implants lost before the prosthetic rehabilitation and eleven implants lost following variable periods in function after the prosthetic phase of the treatment. 11.Cause of implant failures was exfoliation or removal of fixture due to non-osseointegration before the prosthetic rehabilitation or due to fracture of fixture, masticatory pain after the prosthetic rehabilitation. 12.The survival rate of Steri-Oss implants using the Kaplan-Meier statistical analysis was 93.8% at 2 year and 86.6% at 5 year, In all cases, implant losses occured predominantly in the healing period. There was a steep decline in the rate of implant loss after the first year. 13.The survival rate of Steri-Oss implants in the anterior region was 94.8% at 2 year and 94.8% at 5 year and that in the posterior region was 92.8% at 2 year and 75.9% at 5 year. In conclusion, this study revealed a number of parameters and guidelines for achieving an optimal success rate in osseointegration.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제32권6호
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• pp.511-520
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• 2010

Purpose: This study was conducted in order to compare the efficacy of osseointegration of three different calcium metaphosphate (CMP) coated implants in the rabbit's femur. Materials and Methods: Twenty four rabbits and three different type of CMP coated implants and RBM implants were used in this study. The animals were divided into 4 groups on the basis of implant surface characteristics. Two implants were installed into the condyle of femur of each rabbits. The animals were sacrificed at 2 and 4 weeks after installation. The undecalcified specimens were prepared for histological, radiological examination and histomorphometric analysis of implant-bone contact ratios (BIC) and bone area ratio (BA). Results: Two implants were failed to osseointegrate and implant success rate was 95.2%. There were not any significant inflammatory response in all groups. Fluorescent image at 4 weeks shows that remodeling is slower in RBM group than CMP group. CMP III showed more active remodeling than CMP I, II. In histomorphologic analysis, BIC ratio at 2 weeks was lower than 4 weeks. Conclusion: The results suggest that the ratios of CMP coated implants were higher than that of RBM control group but there is no significantly difference between RBM group and CMP group. In conclusion, CMP coated implant had more clinical availability than RBM implants.

• 한국환경복원기술학회지
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• 제14권3호
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• pp.115-141
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• 2011

In urban space, public space is publicly or privately owned space freely accessible by the public. Privately owned public space to the public hosts small-scale rest facilities to serve the public in buildings of certain purposes and sizes for the sake of pleasant urban environment. The Building Act and building ordinances formulate a set of criteria for management and easement of construction standards as well as the area. When creating privately owned public space, one can get incentives through the easement of floor space index and height limit. The purposes of this study were to investigate and analyze privately owned public open space, which is freely accessible by the public, and its adjacent streets and to propose plans to improve the regulations for securing privately owned public space for more rational and practical legal applications. The study then proposed some plans to help to increase the quality of privately owned public space including applying the coefficient to suggest the type of privately owned public space fit for the features of the streets and measure the appropriate utility level differently and distinguishing the mandatory items according to the facility regulations in privately owned public space from the ones qualified for additional points in case of installation. The types of privately owned public open space should be applied differently and the content of facilities intended should be different according to whether it will serve as a resting place or grant more importance on traffic by walking, depending on the features of its adjacent streets. The privately owned public space, the frontage space of building, and the adjacent sidewalks should become a whole and be regarded as one space from the integrated perspective. The results of the study claim further significance in that it investigated privately owned open space and roadside across Seoul. They will serve as useful data to solve the problems with the privately owned public space of the city, which destroys spatial continuity by focusing on the quantitative increase of privately owned open space and creating individual privately owned open spaces and builds high-rise buildings alienated from the existing spaces, and to increase the quality of future privately owned public space.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제38권4호
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• pp.204-211
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• 2012

Objectives: Dental implants installation in patients with diabetes remains controversial as altered bone healing around implants has been reported. And little is known about the biological factors involved in bone healing around implants. The present study aimed to investigate the biological markers around immediately placed implants in rats with controlled and uncontrolled diabetes. Materials and Methods: Twenty rats (40 sites) were divided into the control, insulin-treated and diabetic groups. The rats received streptozotocin (60 mg/kg) to induce diabetes; animals in the insulin-treated group also received three units of subcutaneous slow-release insulin. Two threaded titanium alloy implant ($1.2{\times}3mm$) were placed in the extraction socket of the both maxillary first molars and allowed for healing. Bone blocks including implant were harvested at 3 days, 1, 2 and 4 weeks. The levels of bone morphogenetic protein (BMP)-4, transforming growth factor (TGF)-${\beta}1$, osteocalcin (OC) and osteonectin (ON) were measured in the peri-implant osseous samples by RT-PCR. Results: The BMP-4 level increased immediately in all groups by day 3, then decreased abruptly in the control and the insulin-treated groups. However, by week 4, all groups showed mostly the same amount of BMP-4 expression. The level of TGF-${\beta}1$ also instantly increased by day 3 in the insulin-treated group. This level elevated again reaching the same values as the control group by week 4, but was not as high as the diabetic group. In addition, the expression of OC and ON in the control and insulin-treated groups was higher than that of the diabetic group at 2 weeks and 4 weeks, indicating active bone formation in these groups. Conclusion: The immediate placement of titanium implants in the maxilla of diabetic rat led to an unwanted bone healing response. Conclusively, the results of this study suggest that immediate implant insertion in patients with poorly controlled diabetes might be contraindicated.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.5-6
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• 2002

The new spectrometer for X-ray Induced Electron Emission Spectroscopy (XIEES) .has been recently developed in KRISS in collaboration with PTI (Russia). The spectrometer allows to perform research using the XAFS, SXAFS, XANES techniques (D.C.Koningsberger and R.Prins, 1988) as well as the number of techniques from XIEES field(L.A.Bakaleinikov et all, 1992). The experiments may be carried out with registration of transmitted through the sample x-rays (to investigate bulk samples) or/and total electron yield (TEY) from the sample surface that gives the high (down to several atomic mono-layers in soft x-ray region) near surface sensitivity. The combination of these methods together give the possibility to obtain a quantitative information on elemental composition, chemical state, atomic structure for powder samples and solids, including non-crystalline materials (the long range order is not required). The optical design of spectrometer is made according to Johannesson true focusing schematics and presented on the Fig.1. Five stepping motors are used to maintain the focusing condition during the photon energy scan (crystal angle, crystal position along rail, sample goniometer rail angle, sample goniometer position along rail and sample goniometer angle relatively of rail). All movements can be done independently and simultaneously that speeds up the setting of photon energy and allows the using of crystals with different Rowland radil. At present six curved crystals with different d-values and one flat synthetic multilayer are installed on revolver-type monochromator. This arrangement allows the wide range of x-rays from 100 eV up to 25 keV to be obtained. Another 4 stepping motors set exit slit width, sample angle, channeltron position and x-ray detector position. The differential pumping allows to unite vacuum chambers of spectrometer and x-ray generator avoiding the absorption of soft x-rays on Be foil of a window and in atmosphere. Another feature of vacuum system is separation of walls of vacuum chamber (which are deformed by the atmospheric pressure) from optical elements of spectrometer. This warrantees that the optical elements are precisely positioned. The detecting system of the spectrometer consists of two proportional counters, one scintillating detector and one channeltron detector. First proportional counter can be used as I/sub 0/-detector in transmission mode or by measuring the fluorescence from exit slit edge. The last installation can be used to measure the reference data (that is necessary in XANES measurements), in this case the reference sample is installed on slit knife edge. The second proportional counter measures the intensity of x-rays transmitted through the sample. The scintillating detector is used in the same way but on the air for the hard x-rays and for alignment purposes. Total electron yield from the sample is measured by channeltron. The spectrometer is fully controlled by special software that gives the high flexibility and reliability in carrying out of the experiments. Fig.2 and fig.3 present the typical XAFS spectra measured with spectrometer.

• 유기물자원화
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• 제26권1호
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• pp.55-64
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• 2018

본 연구는 유기성폐자원(가축분뇨, 음식물류폐기물, 음식물류폐수 등)의 바이오가스 이용에 대한 적정 설계 및 운전 기술지침서 마련하고자 현장조사와 정밀모니터링 등을 실시하였다. 정부의 중장기 바이오가스화 정책에 따라 폐자원의 자원화 시설 확충이 활발히 추진되고 있다. 하지만 생산된 바이오가스를 이용하여 발전 및 스팀으로 활용하는 시설은 효율이 아직은 저조하고 잦은 고장이 발생되고 있다. 현재 운영 중인 바이오가스화 11개소를 대상으로 바이오가스 이용 공정별 특징 및 문제점을 분석하고 혐기소화조 현장 시료의 계절별 정밀모니터링을 실시하여 바이오가스 이용 공정 흐름에 따른 설계 운영 가이드라인을 제시하였다. 현장조사 수행 결과, 바이오가스 이용 공정에서 바이오가스의 적정 제습, 황화수소 전처리, 발전시설의 적정처리 등이 주요 문제점으로 조사되었다. 따라서 유기성폐자원의 바이오가스화 시설의 단점을 보완하고 바이오가스 이용 최적화 방안을 마련하기 위하여 현장지설에 대한 정밀조사를 실시하여 공정별 문제점들을 정리하였다.

• 한국산림과학회지
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• 제96권6호
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• pp.652-660
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• 2007

1989년부터 2005년까지 시공된 전라북도 내의 민유임도 216개 노선의 설계도서를 대상으로 임도 설계상의 주요 공종변화를 분석하였다. 전라북도의 연평균 민유임도 시설거리는 녹색임도 정책 시행 이전단계에 비해 녹색임도 정책 시행 이후 대폭 감소하였다. 토사절취작업은 1990년부터 블도저에서 블도저와 굴삭기 혼용으로 바뀌었다. 비탈면 녹화공은 초기에는 잔디심기와 족제비싸리심기가 주종을 이루었는데, 녹색임도정책 시행단계(2단계)부터 종자뿜어붙이기와 줄파종의 혼용, Coir net 또는 볏짚거적 덮기 등으로 발전하였다. 횡단배수관의 경우, 배수관의 설치 간격은 3단계에 평균 92 m로 감소하였고, 규격은 2단계 이후에 대부분 600 mm 이상으로 확대되었으며, 재료는 모두 파형강관으로 설계되었다. 콘크리트포장은 1단계의 평균 40 m/km에서 3단계에는 240 m/km로 현저히 증가하여 임도의 안정성과 기능성이 제고되었다. 비탈안정구조물은 석축이 주종을 이루고 있지만, 1993년 이후부터 콘크리트옹벽과 돌망태옹벽 등도 많이 설계되었다. 이와 같은 분석을 바탕으로 본 연구에서는 주요 공종을 대상으로 몇 가지 개선방안을 제안하였다.

• 유기물자원화
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• 제26권2호
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• pp.95-103
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• 2018

바이오가스 이용 최적화를 위해 탈황 및 제습 전처리시설 가이드라인으로 $H_2S$ 농도는 철염으로 처리가능한 150 ppm으로 설정하고, 제습은 발전기 운전 적정수분 값이며 EU회원국에서 바이오가스 활용 시 적용하는 상대습도 60 %로 설정하였다. 국내 바이오가스 평균 온도인 $31^{\circ}C$에서 상대습도 60 %으로 적용한다면 노점온도 $22^{\circ}C$, 절대습도 $20.57g/m^3$으로 나타낼 수 있으며, 전처리 설비가 적절히 가동된다면 가이드라인에 만족하여 바이오가스의 이용이 최적화 될 것으로 사료된다. 바이오가스 이용 최적화를 위해 발전기 설비 가이드라인을 설정하고자 하였다. 바이오가스 적정 이용량으로는 전체 가스 발생량의 90 % 이상을 이용해야하며, 발전기 시설의 용량은 여유율을 10~30 %로 설정해야 한다. 발전기에 유입가스의 압력을 균등화하기 위해서는 가스 균등조(buffer tank)를 설치하며, 발전실 평균온도는 $45^{\circ}C$이하로 유지한다. 소화조에서 일정한 메탄농도로 가스가 생성되지 않아 효율이 저하되므로 메탄농도에 변화에 따른 공기연료비 제어시스템을 설치가 요구된다. 본 연구에서는 유기성폐자원의 바이오가스 생산 및 이용을 최적화를 위해 현장시설의 정밀모니터링과 시설별 에너지수지를 분석하고, 현장문제 해결방안에 대해서 조사하여 전처리시설 및 발전기 등의 설계 및 운전 가이드라인을 제시하고자 한다.