• 구강회복응용과학지
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• 제17권4호
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• pp.245-256
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• 2001

The purpose of this study is to analyze the mechanical stress and displacement on the jaws during the simulated bilateral clenching task on the three-dimensional finite element model of the dentated skull with unilateral molar loss. For this study, the computed tomography(G.E.8800 Quick, USA) was used to scan the total length of human skull in the frontal plane at 2.0mm intervals. The fully assembled finite element model consists of the articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. The FE model was used to simulate the bilateral clenching in intercuspal position. The loading condition was the force of the masseter muscle exerted on the mandible as reported by Korioth et al. degrees of freedom of the zygomatic region where the masseter muscle is attached were fixed as restraints. In order to reflect the actual action of the muscles force, the displacement of the region was attached where the muscle is connected to the temporal bone and restraint conditions were given values identical to values at the attachment region of the masticatory muscle but with the opposite direction of the reaction from when the muscle force is acted on the mandible. Although the mandible generally has higher displacement and von Mises stress than the maxilla, its mandibular corpus on the molar-loss side has a higher stress and displacement than the molar-presence side. Because the displacement and von Mises Stress was the highest on the lateral surface of mandibular corpus with molar loss, the stress level of the condyle on the molar-loss side is greater than that of the molar-presence side, which in turn caused the symphysis of the mandible to bend. In conclusion, the unilateral posterior bite collapse with molar loss under para-functional activities such as bruxism and clenching can affect the stress concentration on the condyle and mandibular corpus. It is therefore necessary to consider the biomechanical function of dento-skeleton under masticatory force while designing the occlusal scheme of restoration on alveolar bone with the posterior collapse.

• 자원환경지질
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• 제26권3호
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• pp.311-325
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• 1993

The Ohto and Tohyun copper mine which are located 4 km southeast of Euiseong, Gyeongsangbukdo, Republic of Korea show various common geologic and mineralogic features. Both copper deposits are of hydrothermal-vein types, and associated with fracture system developed during formation of the Geumseong-san caldera in late Cretaceous age. According to structures and mineral assemblages, the mineralization processes have progressed in four stages: three hypogene mineralization stages and one supergene stage. Three hypogene stages are 1) stage I forming $N5{\sim}20^{\circ}E$ veins in the Ohto mine, 2) stage II building $N5^{\circ}W{\sim}N5^{\circ}E$ veins in the Tohyun mine, and 3) stage ill bringing $N80^{\circ}E$ veins which crosscut veins of the stage II. The vein ores consist mainly of pyrite, arsenopyrite, galena and chalcopyrite, minor or trace amounts of magnetite, hematite, pyrrhotite, stannite, bournonite, boulangerite, stibnite, galenobismutite, native bismuth, marcasite, geothite and malachite. The main gangue minerals are quartz and calcite. Wallrock is altered by sericitization, chloritization, pyritization, carbonitization and argillization. Arsenic and copper contents in arsenopyrite increase from stage I to stage III (from 31.28 to 33043 atom.% As) and (from 0.04 to 0040 atom.% Co). Going from stage I to stage III Fe and Mn contents in sphalerite decreases from 12.56 to 0.44 wt.% and from 0.24 to 0.01 wt.%, respectively. The compositional data of arsenopyrite in the early stage I indicate a temperature of $420{\sim}365^{\circ}C$ and sulfur fugacity of $10^{-6.5}{\sim}10^{-8.3}$ atm. Chalcopyrite and pyrrhotite assemblage suggest that Middle stage I was deposited at below $334^{\circ}C$. The compositional data of arsenopyrite in early stage II suggest a temperature range of $425{\sim}390^{\circ}C$ and sulfur fugacity codition of $10^{-6.4}{\sim}10^{-7.3}$ atm. Based on fluid inclusion the Middle stage II was regarded as to be deposited at $420{\sim}337^{\circ}C$ (Chi et al., 1989). Referring composition of sphalerite and stannite middle-late stage II seem to be deposited around $246^{\circ}C$ and $10^{-16.5}$ atm. sulfur fugacity. The ${\delta}^{34}S$ values of sulfide minerals in the Stage I, II, III range from 4.9 to 7.6%0 and indicate igneous ore fluid origin. Based on differences in mineral assemblages, chemical composition and chemical environments of Ohto and Tohyun mine its mineralization are considered to be formed at diffent mineralization ages and by different ore fluids.

• 한국대기환경학회지
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• 제26권5호
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• pp.543-553
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• 2010

Almost five million citizens a day are using subways as a means of traffic communication in the Seoul metropolitan. As the subway system is typically a closed environment, indoor air pollution problems frequently occurs and passengers complain of mal-health impact. Especially $PM_{10}$ is well known as one of the major pollutants in subway indoor environments. The purpose of this study was to compare the indoor air quality in terms of $PM_{10}$ and to quantitatively compare its source contributions in a Seoul subway platform before and after installing platform screen doors (PSD). $PM_{10}$ samples were collected on the J station platform of Subway Line 7 in Seoul metropolitan area from Jun. 12, 2008 to Jan. 12, 2009. The samples collected on membrane filters using $PM_{10}$ mini-volume portable samplers were then analyzed for trace metals and soluble ions. A total of 18 chemical species (Ba, Mn, Cr, Cd, Si, Fe, Ni, Al, Cu, Pb, Ti, $Na^+$, $NH_4^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, and ${SO_4}^{2-}$) were analyzed by using an ICP-AES and an IC after performing proper pre-treatments of each sample filter. Based on the chemical information, positive matrix factorization (PMF) model was applied to identify the source of particulate matters. $PM_{10}$ for the station was characterized by three sources such as ferrous related source, soil and road dust related source, and fine secondary aerosol source. After installing PSD, the average $PM_{10}$ concentration was decreased by 20.5% during the study periods. Especially the contribution of the ferrous related source emitted during train service in a tunnel route was decreased from 59.1% to 43.8% since both platform and tunnel areas were completely blocked by screen doors. However, the contribution of the fine secondary aerosol source emitted from various outside combustion activities was increased from 14.8% to 29.9% presumably due to ill-managed ventilation system and confined platform space.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.472-472
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• 2004

Numerous studies on urban groundwater have been carried out in many other countries. Urban groundwater shows a unique hydrologic system because of complex urban characteristics such as road pavement, sewers and public water supply systems. These urban facilities may change the characteristics of groundwater recharge but contaminate its quality as well. There have been several researches on urban groundwater in Seoul. Seoul has been industrialized very rapidly so that the city has large population. The recent population in Seoul amounts to more than ten millions, corresponding to a very high density of about 17, 000 people/km$^2$. Therefore, many factors affect the groundwater quality and quantity in Seoul. Nowadays, groundwater in Seoul is being extracted for construction, industrial use, and drinking and so on. There are 15, 714 wells in Seoul and its annual usage is 41, 425, 977m$^3$(in 2001). Therefore, systematic studies are needed to properly manage and use the groundwater in Seoul. The purposes of this study in progress are to identify geochemical characteristics of groundwater in Seoul and to determine the extent of groundwater contamination and its relationship with urban characteristics. For this study, groundwater was sampled from more than 400 preexisting wells that were randomly selected throughout the Seoul area. For all samples, major cations together with Si, Al, Fe, Pb, Hg For 200 samples among them, TCE, PCE, BTEX were also analyzed by GC. Our study shows that groundwater types of Seoul are distributed broadly from Ca-HCO$_3$ type to Ca-Cl＋NO$_3$ type. The latter type indicates anthropogenic contamination. Among cations, Ca is generally high in most samples. In some samples, Na and K are dominant. The dominant anions change widely from HCO$_3$ to Cl＋NO$_3$. The anion composition is considered to effectively indicate the contribution of distinct anthropogenic sources. In addition, major ions are positively proportional to total dissolved solid (TDS) except K and NO$_3$. Thus, we consider that TDS may be used as an effective indicator of the extent of pollution. However, the increase of TDS may result from increased water-rock interaction. To determine the extent of groundwater contamination, it is needed to figure out the baseline water quality in Seoul. Furthermore, detailed geochemical studies are required to find out pollution sources and their corresponding hydrochemical parameters.

• 한국토양비료학회지
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• 제10권4호
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• pp.219-224
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• 1978

우리나라 전토양(田土壤) 분석(分析)에 적합(適合)한 토양유효인산분석법을 밝히고자 4개토양(個土壤)을 가지고 토관(土管)에서 대두(大豆)를 재배(栽培)하여 수량(收量) 및 식물체중(植物體中) 인산흡수량(燐酸吸收量)과 토양중(土壤中) 유효인산(有效燐酸) 흡수량(吸收量)과의 관계(關係)를 검토(檢討)한 결과(結果)는 다음과 같다. 1. 대두수량(大豆收量)은 화아분화기(花芽分化期) 식물체중(植物體中) 인산흡수량(燐酸吸收量)과 높은 상관(相關)이 있었고 식물체중(植物體中) 인산흡수량(燐酸吸收量)은 각방법별(各方法別) 토양유효인산(土壤有效燐酸)과 높은 상관관계(相關關係)가 있었으며 그 상관도(相關度)는 Olsen P${\geq}$Lancater P>Bray No.1 P>Bray No.2 P>Truog P의 순(順)이었다. 2. 각방법(各方法)에 의(依)하여 침출(浸出)된 토양유효인산(土壤有效燐酸)의 절대치(絶對値)의 크기는 Bray No. 2 P>Lancaster P${\geq}$Bray No.1 P>Truog P의 순(順)이었다. 3. 각방법별(各方法別) 토양유효인산함량(土壤有效燐酸含量)은 무기태인산(無機態燐酸)의 각분별정량치(各分別定量値)와 높은 상관관계(相關關係)를 나타냈다. 4. 결론적(結論的)으로 대두수량(大豆收量)과 토양유효인산(土壤有效燐酸)과의 관계(關係)에 있어서 Lancaste P, Bray P 및 Olsen P는 그 정도(程度)에 있어서 거의 유사(類似)한 것이었으나 Olsen P가 가장 높은 상관도(相關度)를 보였다.

• 대한환경공학회지
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• 제27권11호
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• pp.1180-1185
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• 2005

본 연구에서는 철이 주성분 이면서 다양한 금속산화물의 조성을 갖는 채광물질인 철광사(Iron Sand)를 구리 혹은 납을 함유한 합성폐수 처리에 대한 적용성을 조사하였다. 먼저 철광사의 내산성을 조사하기 위해 pH $2{\sim}4.5$ 범위에서 철 및 알루미늄의 용출특성을 조사였을 때, 가장 많은 조성을 갖는 철의 용출량은 강산성인 pH 2에서도 수질오염 배출기준 이하로 나타났다. 알루미늄의 경우 pH 2에서는 상당량의 용출현상이 나타났지만 pH 3 이상에서는 용출농도가 급격히 감소하였다. 이러한 내산성 실험결과는 철광사를 pH 3 이상에서의 폐수처리에 적용하는 데는 큰 문제가 없는 것을 제시한다. 철광사의 중금속 흡착능력을 조사하기 위해 구리 및 납을 흡착질로 사용하고 실험실 규모의 회분식 흡착실험과 칼럼 여과실험을 실시하였다. pH 5에서 철광사에 의한 구리이온의 제거는 반응초기 시간대에 빠르게 이루어졌으며 2시간이 경과되었을 때 구리 주입량의 50%가 제거되었으며 24시간 경과 후에 거의 완전한 흡착평형에 도달하였다. 철광사에 대한 Cu(II) 및 Pb(II)의 흡착은 pH 2 이상에서 증가되기 시작하였으며 pH 6 이상에서는 거의 모든 흡착질들이 제거되는 전형적인 양이온형 흡착경향을 보였다. 철광사에 대한 구리 및 납 흡착질의 농도비 변화에 따른 흡착등은 실험결과, 구리 및 납의 최대 흡착량은 각각 2,170 mg/kg 및 3,450 mg/kg으로 나타났다.

• 대한환경공학회지
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• 제22권11호
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• pp.2085-2095
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• 2000

적니는 보오크사이트로부터 수산화알루미늄/알루미나를 제조하는 공정에서 발생되는 부산물이다. 본 연구에서는 적니를 여러 가지 조건으로 산처리하여 적니에 포함되어 있는 알루미늄과 철을 산으로 침출시켜 무기응집제를 제조하였다. 적니와 산의 비율이 1/10(g/mL)인 경우 5M $H_2SO_4$와 $85^{\circ}C$에서 반응할 때, 9M HCl과 $25^{\circ}C$에서 반응할 때 알루미늄과 철의 최적 침출효율을 얻을 수 있었다. 또한 수용액에서 중금속이온($Pb^{2+}$, $Cd^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Cr^{3+}$), 탁도, 인산염인($PO_4{^{3-}}-P$) 제거실험을 여러 가지 실험조건으로 수행하였다. 실험결과, 본 연구에서 개발된 응집제는 수용액에서 중금속이온, 탁도와 인산염인에 대해 우수한 제거능력을 보이는 것으로 확인되었다.

• 한국대기환경학회지
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• 제24권4호
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• pp.439-454
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• 2008

The purpose of this study was to extensively identify $PM_{10}$ sources and to estimate their contributions to the study area, based on the analysis of the $PM_{10}$ mass concentration and the associated inorganic elements, ions, and total carbon. The contribution of $PM_{10}$ sources was estimated by applying a receptor method because identifying air emission sources were effective way to control the ambient air quality. $PM_{10}$ particles were collected from May to November 2007 in the Yongin-Suwon bordering area. $PM_{10}$ samples were collected on quartz filters by a $PM_{10}$ high-volume air sampler. The inorganic elements (Al, Mn, V, Cr, Fe, Ni, Cu, Zn, Cd, Pb, Si, Ba, Ti and Ag) were analyzed by an ICP-AES after proper pre-treatments of each sample. The ionic components of these $PM_{10}$ samples ($Cl^_$, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$) were analyzed by an IC. The carbon components (OC1, OC2, OC3, OC4, OP, EC1, EC2 and EC3) were also analyzed by DRI/OGC analyzer. Source apportionment of $PM_{10}$ was performed using a positive matrix factorization (PMF) model. After performing PMF modeling, a total of 8 sources were identified and their contribution were estimated. Contributions from each emission source were as follows: 13.8% from oil combustion and industrial related source, 25.4% from soil source, 22.1% from secondary sulfate, 12.3% from secondary nitrate, 17.7% from auto emission including diesel (12.1%) and gasoline (5.6%), 3.1% from waste incineration and 5.6% from Na-rich source. This study provides information on the major sources affecting air quality in the receptor site, and therefore it will help us maintain and manage the ambient air quality in the Yongin-Suwon bordering area by establishing reliable control strategies for the related sources.

• Clinical and Experimental Pediatrics
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• 제49권1호
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• pp.18-23
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• 2006

목 적 : 영양상태, 환경 오염원에 노출, 질병상태의 한 검진 방법으로서 모발 미네랄검사의 타당성에 대해 아직 많은 이견이 있으며 아직 국내 정상 소아의 참고치는 연구된 바 없다. 이에 저자들은 건강한 아동들의 모발 미네랄 함량의 정상 참고치를 산출하고 그 특성을 알아보고자 하였다. 방 법 : 서울시의 북부지역에 거주하는 3-12세 사이의 질병이 없는 건강한 정상 아동 223명(남아 110명, 여아 113명, 평균 연령 $8.8{\pm}2.2$세)을 대상으로 모발을 채취하여 유도결합플라즈마질량분석기(ICP-MS)를 통해 영양 미네랄 11가지(나트륨, 마그네슘, 인, 칼륨, 칼슘, 크롬, 망간, 철, 구리, 아연, 셀레늄)와 독성 미네랄 6가지(알루미늄, 비소, 카드뮴, 바륨, 수은, 납)의 함량을 측정하고 이를 분석하였다. 결 과 : 칼슘 및 마그네슘의 농도는 여아에서 남아보다 높았고 카드뮴, 납 및 크롬의 농도는 남아에서 여아보다 높았다. 아연, 칼슘, 마그네슘, 구리 및 수은은 연령이 증가할수록 모발 중 함량이 증가하는 상관관계를 보였다. 한국 아동의 모발 미네랄 함량의 참고치를 외국과 비교하였을 때 우리나라 아동은 아연치가 외국에 비해 낮은 경향을 보였다. 결 론 : 본 연구를 통해 국내 정상 아동의 모발 미네랄 함량의 기준치가 제시되었으며 본 연구에서 제시된 참고치가 한국 아동들의 여러 가지 질병과 모발 내 미네랄 함량과의 관계를 연구하는 데 유용한 기초 자료로 쓰일 것이라 사료된다.

• Ocean and Polar Research
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• 제26권2호
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• pp.199-205
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• 2004

$SiO_2$ and CaO are added to decrease the smelting temperature in the reduction-smelting method for manganese nodule processing. These elements are components of the manganese nodules and might be very important controlling factors in the processing due to the locally variable content. The 707 chemical data of manganese nodules acquired from 1994 to 2001 in KODOS(Korea Deep Ocean Survey) area were used for the hierarchical cluster analysis. The chemical data were classified by the morphological types, and the averages of the chemical data for each station were classified by the facies groups and the localities. All data are plotted on the $SiO_2-CaO-MnO$ phase diagram at $1773^{\circ}K$ to compare with the best compositional area in the nodule smelting. Variations and distributions of $SiO_2$ and CaO in KODOS nodules were also reviewed. The mineral phases assigned by the cluster analysis are CFA(Carbonate Fluorapatite), Fe-oxide, Al-silicate, and Mn-oxide. MnO contents are generally higher than $SiO_2$ contents in most of the morphological types except for the Is- and It-type. The Dt- and Tt-type show wider range and the E-types show high anomaly in their CaO contents. The stations which belong to facies group A and B show generally higher MnO contents than $SiO_2$ contents, however, the stations of facies group C and D show wide range in their MnO and $SiO_2$ contents. It seems to be very important to control the $SiO_2$ contents in the processing because of the wide range in the northern area. The additions of approximately 10 wt.% CaO and 10 wt.% $SiO_2$ are recommended for the northern area, whereas, the additions of approximately 10 wt.% CaO and 20 wt.% $SiO_2$ are recommended for the southern area.