제주도 지하수 질산염 농도의 시·공간적 변화 특성: 장기(1993-2015) 모니터링 자료의 평가

김호림(Ho-Rim Kim),오준섭(Junseop Oh),도현권(Hyun-Kwon Do),이경진(Kyung-Jin Lee),현익현(Ik-Hyun Hyun),오상실(Sang-Sil Oh),감상규(Sang-Kyu Kam),윤성택(Seong-Taek Yun) 대한자원환경지질학회 2018 자원환경지질 Vol.51 No.1

1993년부터 2015년까지 관측된 제주도 지하수 장기모니터링 관측정(N = 4,835)에서 수집된 지하수 수질자료(N = 21,568)를 기반으로 질산성질소의 시공간적 변동 특성을 평가하였다. 제주도 지하수의 질산성질소 농도의 중앙값은 2.5 mg/L로서 다른 국가나 대륙의 조사 결과에 비해 다소 높거나 유사한 것으로 나타났다. 또한 지하수 용도, 행정구역 및 고도 별로 유의한 차이를 보였다. 특히, 산간 지역에 비해 저지대 해안가에 위치한 농업 및 주거지역에서 농도가 높음을 확인하였다. Mann-Kendall 및 Sen’s slope 분석을 활용한 질산성질소 농도의 추세 분석 결과, 하류 저지 대에 비해 중산간지역에서의 질산성질소 농도 증가 경향이 뚜렷하였다. 제주도 내 토지 피복의 시계열 변화 특성과 결부 지어 보면, 중산간지역의 오염 증가 추세는 농업지역의 확장 등 인위적 활동 증가에 기인한 결과로 판단된다. 반면,기지정된 지하수자원특별관리구역에서는 전반적으로 질산성질소 농도의 감소 경향이 나타났는데, 이는 지하수 관리 측면에서 수질관리를 위한 적극적인 정책이 유효함을 시사한다. 본 연구에서는 제주도 지하수의 질산성질소 오염관리를 위한 적정 방안을 제안한다. The spatio-temporal variations of nitrate concentrations in groundwater of Jeju Island were evaluated by an analysis of time series groundwater quality data (N = 21,568) that were collected from regional groundwater monitoring (number of wells = 4,835) for up to 20 years between 1993 and 2015. The median concentration of NO 3 -N is 2.5 mg/L, which is slightly higher than those reported from regional surveys in other countries. Nitrate concentrations of groundwater in wells tend to significantly vary according to different water usage (of the well), administrative districts, and topographic elevations: nitrate level is higher in low-lying agricultural and residential areas than those in high mountainous areas. The Mann-Kendall trend test and Sen’s slope analysis show that nitrate concentration in mid-mountainous areas tends to increase, possibly due to the expansion of agricultural areas toward highland. On the other hand, nitrate concentrations in the Specially Designated Groundwater Quality Protection Zones show the temporally decreasing trend, which implies the efficiency of groundwater management actions in Jeju. Proper measures for sustainable groundwater quality management are suggested in this study.

터빈 효율의 열역학 제2법칙적 고찰

오국택,조경철,정평석 嶺南大學校 工業技術硏究所 1998 工業技術硏究所論文集 Vol.26 No.2

Conventional efficiencies of the adiabatic expansion process such as isentropic efficiency and polytropic efficiency can be explained as the special cases of exergetic efficiencies replacing the reference atmospheric temperature with temperatures which can be determined in the process itself. It enables to explain the meaning of the efficiencies more general and, to define other efficiency such as minimum isentropic efficiency by specifying proper reference temperatures.

초내식성 스테인리스강 선재와 브라켓의 내식성 및 금속 이온 용출 특성

오근택,정경진,황충주,박용수,김경남 大韓齒科器材學會 2001 대한치과재료학회지 Vol.28 No.4

Metallic orthodontic appliances are known to release metal ions in an oral cavity. It is not advisable that toxic corrosion products derived from the appliances is absorbed into the body. Metal ions release from orthodontic appliances is known to have large effects on the result of orthodontic treatment and systemic health. Metal bracket and wire were made of super stainless steel(S32050) with high corrosion resistance. The corrosion resistance and ion release property of S32050 and conventionally used appliances were examined. Four types of wire were ligated in either super stainless steel(SB) or Tomy bracket(TB) with O-ring, and then each group was immersed in an artificial saliva at 37℃ for 12 weeks. Amount of released metal ions was measured with immersion time by graphite furnace atomic absorption spectroscopy and surface morphology was investigated. S32050 showed the low passive current density of about 1 μA/㎠ and the stable passive region to a high potential in artificial saliva. S32050 appliances did hardly release nickel ions in artificial saliva. S32050 wire(SRW) and NiTi wire(NW) didn't show significant difference of Ni ion release with immersion time, meanwhile, Remanium wire(RW) showed significant difference in 12 weeks. Ni ion releasce from the brackets didn't show any significant difference with immersion time and between SB and TB. Amounts of Ni ion released from TB-SRW showed significant difference in 12 weeks, those from TB-RW showed significant difference from 4 weeks later and highest release among all groupsin12weeks. TB-NW released little Ni ion for all immersion time and showed significant difference from 4 weeks later, TB-TW(TMA wire) showed significant difference in 12 weks. SB-SRW didn't show any significant difference and SB-RW signigicant difference in 12 weeks,but lower compared with TB group. SB-NW and SB-TW didn't show any significant difference. Corrosion products didn't be observed in mostly groups during the immersion time, except that in TB-RW, they were observed on the bracket surface between O-ring and wire from 8 weeks later. Super stainless steel wire had good corrosion resistance compared with stainless steel wire, and it is believed that it can be used as orthodontic material for bracket and wire.

Grade 2, 4 티타늄 마이크로 임플랜트의 식립 및 제거 토크와 식립 후 조직학적 반응의 비교

강승택,권오원,성재현,경희문,박효상 대한치과교정학회 2006 대한치과교정학회지 Vol.36 No.3

마이크로 임플랜트는 순티타늄과 티타늄 합금을 사용하고 있다. 순티타늄의 경우 grade가 낮을 수록 생체적합성은 증가하나 기계적 성질이 낮다. 이에 본 연구에서는 순티타늄 grade 2와 grade 4를 재료로 한 마이크로 임플랜트를 각각 토끼의 다리뼈에 식립한 후 2, 8, 12주의 시간경과에 따른 조직학적 소견의 차이와 식립, 제거 시의 최대토크의 측정으로 그 티타늄 종류에 따른 차이를 살펴보았다. 토끼의 경골에 식립한 티타늄의 종류에 따른 식립시 및 시간의 경과에 따른 제거시의 토크를 측정하여 다음과 같은 결론을 얻었다. 첫째, grade 2와 grade 4간의 식립 시 최대토크의 차이는 없었다. 둘째, 식립 후 2, 8, 12주 후의 제거 시 최대토크 측정에서 전체 마이크로 임플랜트의 그룹간 차이는 없었다. 셋째, 2주에서 8주로 시간이 경과함에 따라 제거 시 최대토크가 유의하게 증가하였으며 8주와 12주간에는 유의한 상관관계가 없었다. 따라서 유지력은 grade 2 티타늄과 비슷하지만 물리적 성질이 더 단단한 grade 4 티타늄을 마이크로 임플랜트 재료로 사용하는 것이 좋은 것으로 생각된다. The purpose of this study was to evaluate the light microscopic features and the maximum insertional and removal torque value of microimplants, made from titanium grade 2 or 4, in the tibia of 6 rabbits. First, the maximum torque values of microimplants at implantation were measured. After 2, 8, and 12 weeks of healing time, the microimplant-containing segments of tibia of 2 rabbits were removed and the maximum removal torque of each microimplant were measured. Comparisons of histologic examination and insertional and removal torque values were carried out for the two groups of microimplants. Removal torque values were significantly increased in both groups after 8 and 12 weeks as compared to 2 weeks after implantation. Other values measured did not show any statistically significant differences and there were no histological differences between grade 2 and 4 titanium. Based on these results, this study showed that there were no significant differences between grade 2 and 4 titanium. It seems better to use grade 4 titanium for making microimplants because grade 4 titanium is mechanically harder than grade 2 titanium and has similar retention.

금호강 유역 산림의 경관생태적 패턴분석

박경훈,정성관,이현택,오정학,김경태 한국지리정보학회 2004 한국지리정보학회지 Vol.7 No.3

산림의 단편화와 같은 인위적 교란은 유역생태계의 지속성에 영향을 미치기 때문에, 본 연구는 각종 개발사업에 따른 산림의 단편화를 사전에 예방하기 위해서 경관지수와 GIS를 이용하여 금호강 유역에 분포하는 산림구조를 정략화하였다. 소유역 단위의 경관지수값은 인자분석에 의해 전체분산을 또% 정도 설명하는 3개의 공통인자를 단순화하였다. 산림단편화 정도는 소유역별 인자점수를 토대로 계산하였고, 이는 도시지역 면적률(r=0.827, p<0.01, R2=0.685), 고도(r=-0.637, p<0.01)그리고 경사도(r=-0.593, p<0.01)와 상호관련성이 있는 것으로 나타났다. 이상과 같이 본 연구는 금호강 유역관리를 위한 산림경관의 건전성 및 구조적 패턴을 평가하기 위한 방법론과 경관지수값을 제시하였다. 향후에는 경관패턴 및 그 변화가 유역환경의 건전성에 미치는 영향을 규명하기 위한연구가 필요할 것이다. An artificial disturbance like fragmentation in watershed forest has impacted a sustainability of watershed ecosystem, therefore this research quantified the landscape structure in the Geumho river watershed using landscape indices and GIS. Landscape indices were calculated from the forest distributed maps for 24 subwatersheds. Three common factors, which explained about 85% of the variation in the original data, were extracted by a factor analysis. The fragmentation gradient in forest landscape, which was calculated from the factor scores, was correlated with proportion of urban land (rte. 827, p<0.01, R²=0.685). elevation (r=-0.637, p<0. 01) and slope gradient (r=-0.593, p<0. 01) . The result of the study presented that the methodology and the values of landscape indices to assess the structural patterns of forest landscape for the Geumho river watershed management. Future research will be directed towards the detection of impacts of landscape patterns and their changes on the integrity of watershed environments.

교정장치로부터의 니켈과 크롬의 유리에 관한 연구

류정현,오소택,강경화,김상철 대한치과교정학회 2003 대한치과교정학회지 Vol.33 No.5

니켈과 크롬은 대부분의 교정장치를 제작하는데 사용되는 합금을 구성하는 주요한 금속이다. 그러나 이들 금속은 과민반응, 피부염, 천식 등의 주요한 원인이 되며, 이들 금속의 우발적인 흡입에 의해 암이 유발될 수 있음이 보고된바 있다. 이에 하악 standard edgewise 브라켓을 이용한 사분악의 교정 장치를 37℃, 0.05% NaCl 용액에 저장하여 교정장치의 부식에 의해 유리된 니켈과 크롬을 Inductively Coupled Plasma(ICP) spectroanalyzer를 이용하여 측정하였다. 교정장치로부터, 1일 평균 9.83-70.0㎍/day의 니켈이 유리되었으나, 크롬은 10ppb 측정한계에서 측정불가능 하였다. 니켈 유리량은 제품에 따라 유의한 차이를 가져왔다. Galvanic 조건이나 Sand blasting 처리는 니켈 유리량에 증가를 가져왔으나 통계학적으로 유의하지 않았다. Nickel and chromium are two major metals used in the alloys of most orthodontic appliances. But these metals arc known to cause hypersensitivity, dermatitis, and asthma. In addition, a significant carcinogenic and mutagenic potential has been demonstrated for compounds containing these metals. The purpose of this study was to find out how much nickel and chromium was released from orthodontic appliances, and which factors would influence the release. The simulated orthodontic appliances were constructed for a half of a mandibular arch and incubated in 0.05% NaCl solution at 37℃. Nickel and chromium release was quantified with an Inductively Coupled Plasma (ICP) spectroanalyzer. The results were as follows 1. From simulated orthodontic appliances, nickel was released 9.83-70.0㎍/day but the release of chromium was not detectable in limit of l0ppb. 2. The amount of nickel release was significantly different between the types of appliances. 3. The galvanic condition increased the amount of nickel release, which was not statistically significant. 4. The sand blasting increased the amount of nickel release, which was also not statistically significant.

Al-8Ti-1B 합금의 응력부식에 관한 연구

김기주,오택열,박경석,백영남 慶熙大學校 材料科學技術硏究所 1994 材料科學技術硏究論集 Vol.7 No.-

The Mechanical Alloying(MA) process with high mechanical properties of dispersion strengthened MA Al-Ti-B alloys were invested in order to evaluate their Stress Corrosion Cracking(SCC) applications. The experimental apparatus of SCC test was slow strain rate test facility. Al-Ti-B alloys had better SCC susceptibility in pH=2.01 or pH=13.2 solution than pH=6.81 solution. In this study Al-Ti-B alloys by MA had more SCC resistance than Al-Ti alloys Al 7075-T73 alloys. But, in addition of B to Al-Ti alloys had the characteristics of brittle, in binary Al-Ti alloys was ductile.

유한요소법을 이용한 Sputtering Coating 장치용 진공용기의 응력해석

이동명,오택열,한경천 경희대학교 산학협력기술연구원 1995 산학협력기술연구논문집 Vol.1 No.-

In this study, stress analysis of the vacuum chamber of sputtering coating equipment was performed and its safely was confirmed. In order to enhance the self-analysis ability of the manufacturer, computer program was developed using finite element technique. Since door and chamber flanges are known to be the weakest parts of the vacuum chamber, the flanges were meshed as bilinear rectangle elements and analyzed. The results are confirmed by commercial software, NASTRAN. The calculated stresses are low enough to modify the chamber structure. This study is expected to be the motivation and the foundations of computer analysis and design technique of the manufacturer.

12주간의 써키트 웨이트트레이닝이 중ㆍ장년기 남성의 건강관련체력에 미치는 영향

이규성,김문희,오경택,김범수 한국체육대학교 체육과학연구소 2000 韓國體育大學校附屬 體育科學硏究所論文集 Vol.19 No.1

The purpose of this study is to examine the change of health related physical fitness. The study conducted the experiment with 24 participants; three groups fo eight participants in each age group(40, 50 and 60's) The subjects are members of the G sports center. The results of this study are as followed. According to comprehensive results of the research, circuit weight training for 12 weeks appears to give a positive effects on middle aged men's health, and that large increase in body fat and lower strength is not an unavoidable result of aging but the result of an unhealthy life style. Putting the proper training for the middle-aged group into systematic and regular practice, exercise can delay the normal aging process and also maintain relative good health physiologically. I think we need to develop more rational and scientific exercise programs to build up physical strength and improve health.

회전익 항공기용 외활형식 착륙장치의 정ㆍ동적 분석에 관한 연구

유용석,이동명,채경덕,오택열 경희대학교 산학협력기술연구원 1996 산학협력기술연구논문집 Vol.2 No.-

It is important to make sure of design's reasonability concerning of structural vibration problems and safety with fulfilling the research and with analyzing the body structures that include the landing gear which has dynamic significant characteristics in helicopter, and to make systematical procedure which obtains engineering data to guarantee the quality of the helicopter that was developed by testing of parts, subsystems and body. In this study, Analysis of landing gear under FAR regulations was attempted, and systematical procedure for static and dynamic characteristics of the landing gear in many subsystems of the helicopter was classified.