• 대한환경공학회지
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• 제33권1호
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• pp.9-15
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• 2011

농업 및 위락용으로 유지용수를 공급받는 군산 미제저수지의 수질 및 퇴적물 오염현황을 파악하고 퇴적물용출, 비점 오염원 및 외부공급수 등 세가지 영양염 유입경로별 오염부하를 비교 분석하였다. 수질분석결과 하절기에 수질이 크게 저하되고 부영양화에 따른 녹조현상이 가장 활발히 나타났으며, 부영양화지수 TSI (secchi depth)는 53.6, TSI (chlorophyll-a)은 57.7 및 TSI (TP)도 56.7로 모두 50 이상의 부영양호 상태를 보였다. 퇴적물오염도 조사결과 조사시기(계절)별 퇴적물 총질소(T-N)함량, 총인(T-P)함량 및 유기물함량의 각 평균은 통계학적으로 유의한 차이가 없는 것으로 나타났으나 시료채취 지점별 평균은 유의한 차이를 나타내 공간적 변화가 뚜렷하였다. 반면, T-N 및 T-P 퇴적물용출율결과는 공간적변화보다 시기별 변화가 뚜렷하였다. 수질 및 퇴적물 데이터의 상관성분석결과, 수질 T-N은 퇴적물 T-N함량 및 퇴적물 유기물함량과 통계학적으로 유의한 상관관계가 있었으나 수질 T-P는 통계학적으로 상관성을 보이는 인자가 확인되지 않았고 퇴적물 영양염 용출율 역시 수질과 통계학적으로 상관성을 보이는 인자가 확인되지 않았다. 미제저수지내 유입경로별 영양염오염부하 산정결과, T-N의 경우 외부 공급수에 의한 오염부하가 월등히 높게 나타났고 T-P의 경우 퇴적물용출부하와 외부 공급수 유입부하는 유사하고 비점유입부하가 상대적으로 적게 나타났다. 미제저수지의 수질개선을 위해서는 영양염오염부하가 상대적으로 높은 외부 공급수(금강호 양수)에 대한 대책이 우선적으로 수립되어야 하며 아울러, 퇴적물로부터 T-P용출을 저감시키는 수질오염저감대책이 필요한 것으로 판단된다.

• The Journal of Advanced Prosthodontics
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• 제15권5호
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• pp.238-247
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• 2023

PURPOSE. The purpose of this study was to assess the effect of resin cement shade on the color of different novel ultratranslucent monolithic zirconia and lithium disilicate veneer materials. MATERIALS AND METHODS. For a total of 40 specimens, flat cylindrical discs with a 9-mm diameter and 0.5-mm thickness were created using CAD/CAM technology. The specimens were divided into five groups according to their material (n = 8) (e.max, Prettau, Aidite, Shofu and Dima) using A1 shade. Resin discs with the same diameter and shade as the specimens served as tooth-colored substructures. Three shades (neutral, light and warm) of resin cement try-in pastes (Variolink Esthetic LC) were used as the luting cement material. The color of each material group was measured before and after cementation using the three cement shades, and the CIE L^*a^*b^* coordinates were obtained with a spectrophotometer. Values for the translucency parameter (TP) and color change delta E (E) before (baseline) and after cementation of each specimen were determined. To compare differences among the material groups within each shade of cement and among various shades of cement within each material, the data were analyzed using one-way ANOVA and post hoc testing. RESULTS. Color coordinates L^*, a^* and b^* significantly changed after the application of try-in pastes relative to baseline values, with a noticeable decrease in lightness (L^*) (P < .05). A significant color change (ΔE) was observed in all tested materials after cementation, with ΔE values exceeding 3.3 (P < .05). Although TP changed after cementation for most materials tested, these changes were not statistically significant (P > .05). Shofu and Dima ceramics showed the lowest TP values, while Aidite and Prettau showed the highest TP values. For e.max, translucency decreased after cementation with neutral and warm shades, and it significantly increased after cementation with a light shade. CONCLUSION. The shade of cement significantly altered the final color of the ceramic veneer material to a level above the threshold at which the clinical perception of color change occurred (> 3.3). The TP was not influenced by the cement shade. The translucency levels of the novel ultratranslucent multilayer monolithic zirconia ceramics Aidite and Prettau were higher than that of the lithium disilicate e.max material.

• 한국작물학회지
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• 제52권3호
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• pp.311-319
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• 2007

본 시험은 질소 용출 속도가 다른 3가지 피복요소가 포함된 완효성 복합비료를 관행 요소시비량의 80 및 100% 수준으로 시용하여 벼 건답직파 및 이앙재배에서 벼 생육, 수량 및 질소이용율을 알아보고 쌀의 품질에 미치는 영향을 조사하였다. 1. LCU의 제형별 $20^{\circ}C$ 및 $30^{\circ}C$에서 수중 용출 속도는 LCU40 > LCU80 > LCU혼합 > LCU100 순으로 빨랐다. 2. 벼 생육 및 수량은 건답직파 및 이앙재배 모두에서 LCU-복비100% > LCU-복비80% > 관행 순으로 높았다. 3. LCU-복비 시용에 의한 질소이용율은 요소시용에 비해 건답직파재배에서는 $4{\sim}7%$, 이앙재배에서는 $11{\sim}13%$ 향상되었으며, 표준시비량의 20%를 감비한 LCU-복비 80% 시용이 단위시비질소의 생산성이 가장 높았다. 4. 단백질 함량은 건답직파 및 이앙재배의 무질소구에서 6.3 및 6.6%로 가장 낮았고, 비료 처리간에는 LCU-복비 80% 시용구에서 각각 6.5 및 6.7%로 관행 요소시용 7.3 및 7.4%에 비해 낮았다. 5. 아밀로즈 함량 및 Mg/K 비는 모든 처리간에 유의성이 없었다. 또한 쌀의 호화특성 중 최고점도 및 강하점도는 LCU-복비 시용에 의해 다소 높았지만 통계적인 유의성은 없었다.

• 생태와환경
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• 제36권3호통권104호
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• pp.381-388
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• 2003

The fertility of stream water in major streams of the Lake Shihwa Watershed was compared using water analyses and algal growth potential test (AGPT) in typical drought seasons from December 2001 to April 2002, The water quality varied considerably depending on streams. These streams were very rich in inorganic nutrients that the nutrient levels and characteristics of each stream could be easily determined. Through AGPT, 63.6% of growth was observed in the average values of each stream, with non-growth accounting for 36.4%. AGPT results showed that 40.9% of the 22 stations were in hypertrophic condition and 54.5% in eutrophic condition. AGPT values were significantly correlated with TIN, $NH_4$, and SRP (p <0.001); compared to other nutrients, however, they were more related to SRP and $NH_4$. Moreover, the values increased with high concentration of N and P and low N/P ratios. Nonetheless, the values were more dependent on P concentration than N concentration. This suggests that the effect of P on the water quality of lake situated in downstream may serve as a potential indicator of phytoplankton development. Depending on the drainage pattern of streams, the wastewaters of wastewater treatment plant (WwTP) and untreated wastewater (UTW) were found to have 53.4% and 46.6%, respevtively, of TIN, 51.9% and 48.1% of $NH_4$, 62.9% and 37.1% of $NO_3$, 62.6% and 37.4% of SRP, and 44.1% and 55.9% of SRSi. The AGPT value was 51.1% in WwTP wastewater and 48.9% in UTW wastewater, the concentration of WwTP wastewater was slightly higher. For untreated wastewaters flowing into the constructed wetland and into the lake, TIN accounts for 43.0% and 57.0%, respectively, of nitrogen components, $NH_4$ 44.4% and 55.6%, $NO_3$ 39.6% and 60.4%, SRP 53.5% and 46.5%, and SRSi 52.3% and 47.7%, respectively. The AGPT value was 58.0% in the constructed wetland and 42.0% in Lake Shihwa; the concentration in streams flowing into the wetland was slightly higher. Therefore, Persistent and large development of phytoplankton in Lake Shihwa cannot be prevented unless a measure tophytoplankton control is implemented. This is because the concentration of nutrients in specific streams flowing into the lake is very high, even though the inflow of water is low.

• 한국환경보건학회지
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• 제39권1호
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• pp.83-89
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• 2013

Objectives: The purpose of this experiment was to illuminate the relationship between the phosphorus removal rate of unit operation and the phosphorus removal rate of phosphorus volume loading in the Ferrous Nutrient Removal process, which consists of an anoxic basin, oxic basin, and iron precipitation apparatus. Methods: This study was conducted in order to improve the effect of nitrogen and phosphorus removal in domestic wastewater using the FNR (Ferrous Nutrient Removal) process which features an iron precipitation reactor in anoxic and oxic basins. The average concentration of TN and TP was analyzed in a pilot plant ($50m^3/day$). Results: The removal rate of T-N and T-P were 66.5% and 92.8%, respectively. The $NH_3-N$ concentration of effluent was 2.62 mg/l with nitrification in the oxic basin even though the influent was 17.7 mg/l. The $NO_3$-N concentration of effluent was 5.83 mg/l through nitrification in oxic basin even though the influent and anoxic basin were 0.82 mg/l and 1.00 mg/l, respectively. The specific nitrification of the oxic basin ($mg.NH_3$-Nremoved/gMLVSSd) was 16.5 and specific de-nitrification ($mg.NO_3$-Nremoved/gMLVSSd) was 90.8. The T-P removal rate was higher in the oxic basin as T-P of influent was consumed at a rate of 56.3% in the anoxic basin but at 90.3% in the oxic basin. The TP removal rate (mg.TP/g.MLSS.d) ranged from 2.01 to 4.67 (3.06) as the volume loading of T-P was increased, Conclusions: The test results showed that the electrolysis of iron is an effective method of phosphorus removal. Regardless of the temperature and organic matter content of the influent, the quality of phosphorus in the treated water was both relatively stable and high due to the high removal efficiency. Nitrogen removal efficiency was 66.5% because organic matter from the influent serves as a carbon source in the anoxic basin.

• 분석과학
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• 제14권3호
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• pp.238-243
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• 2001

K 수계 6개 지점의 호소 퇴적물과 근접된 수질에 대해 $COD_{Mn}$, T-N, T-P, pH를 측정분석 하였다. 퇴적물로부터 분리된 수질이 퇴적물과 근접한 수질보다 COD, T-N, T-P 모두 높은 값을 나타내었으며 그 다음으로 퇴적층 바로 위의 수질이 높은 값을 나타내었다. 직상수와 최상수의 $COD_{Mn}$, T-N, T-P에 대한 수질분석 결과는 1.2~19.0mg/L, T-N, 1.3~6.2mg/L, T-P, 0.05~0.26mg/L의 농도범위를 나타내었다. 이상의 결과로부터 퇴적물이 호소내 수질오염에 영향을 미치는 요인임을 알 수 있었다.

• 생태와환경
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• 제40권3호
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• pp.468-480
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• 2007

도시화는 하천의 수리, 수질 및 수로의 형태를 변화시키고, 수생태계의 조성을 변화시키고 있다. 최근 포천천과 영평천 주변에 많은 인구와 소규모의 공장 등이 유입되어 도시화됨으로써 오, 폐수의 방류량이 증가하였다. 본 연구는 도시화의 정도에 따라 하천 생태계를 구성하고 있는 돌 부착규조 군집의 조성이 다른 것에 기초로 하여 돌 부착규조 군집의 조성, 우점종 및 생태군 별 종 조성과 생물지수(DAIpo)에 의한 수 환경을 평가하였다. 두 하천의 도시화 지수는 포천천의 정점 P-3와 P-5에서 각각 85와 91로 매우 높은 반면에 영평천 주변의 도시화지수는 약 20 이하였다. 본 조사에서 돌 부착규조는 총 141종류로써 2목, 8과, 30속, 128종, 12변종, 1미동정종으로 구성되었다. 출현 종수는 포천천에서$11{\sim}36$종류의 범위였고, 영평천에서 $14{\sim}45$종류의 범위였다. 우점종은 포천천에서 Navicular saprophila, N. subminuscula, Nitzschia palea, Gomphonema pseudoaugur 등이었으며, 영평천에서 Achnanthes alteragracillima, A. convergens, A. minutissima, N. minima, N. fonticola, N. frustulum와 Cymbella minuta var. silesiaca 등으로써 두 하천의 도시화 정도에 따라 뚜렷한 차이를 나타내었다. 도시화 지수와 EC, BOC, COD, TN, TP. 및 DAIpo 등은 높은 상관관계 $(r^2>0.8)$를 나타내었다. 도시화에 따라 유기오염의 정도가 매우 다르며, 이에 따라 돌 부착 규조의 생태군이 포천천에서는 호오탁성종의 종수 및 상대빈도가 매우 높은 반면 영평천에서는 호청수종의 종수 및 상대빈도가 높았다. 생물지수(DAIpo)에 의한 두 하천의 수질은 포천천에서 조사 동안 강부수성(P-3, 4, 5)을 나타내었고, 영평천에서는 빈부수성(Y-1)에서 강부수성(Y-4)까지 다양하게 나타났다.

• Structural Engineering and Mechanics
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• 제14권3호
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• pp.287-306
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• 2002

The assessment of structural performance of transfer structures under potential seismic actions is presented. Various seismic assessment methodologies are used, with particular emphasis on the accurate modelling of the higher mode effects and the potential development of a soft storey effect in the mega-columns below the transfer plate (TP) level. Those methods include response spectrum analysis (RSA), manual calculation, pushover analysis (POA) and equivalent static load analysis (ESA). The capabilities and limitations of each method are highlighted. The paper aims, firstly, to determine the appropriate seismic assessment methodology for transfer structures using these different approaches, all of which can be undertaken with the resources generally available in a design office. Secondly, the paper highlights and discusses factors influencing the response behaviour of transfer structures, and finally provides a general indication of their seismic vulnerability. The representative Hong Kong building considered in this paper utilises a structural system with coupled shear walls and moment resisting portal-frames, above and below the TP, respectively. By adopting the wind load profile stipulated in the Code of Practice on Wind Effects: Hong Kong-1983, all the structural members are sized and detailed according to the British Standards BS8110 and the current local practices. The seismic displacement demand for the structure, when built on either rock or deep soil sites, was determined in a companion paper. The lateral load-displacement characteristic of the building, determined herein from manual calculation, has indicated that the poor ductility (brittle nature) of the mega-columns, due mainly to the high level of axial pre-compression as found from the analysis, cannot be effectively alleviated solely by increasing the quantity of confinement stirrups. The interstorey drift demands at lower and upper zones caused by seismic actions are found to be substantially higher than those arising from wind loads. The mega-columns supporting the TP and the coupling beams at higher zones are identified to be the most vulnerable components under seismic actions.

• The Journal of Advanced Prosthodontics
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• 제10권1호
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• pp.32-42
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• 2018

PURPOSE. The purpose of this study was to derive and compare the inherent color (hue angle, chroma), translucency ($TP_{SCI}$), surface gloss (${\Delta}E^*_{SCE-SCI}$), and surface roughness ($R_a$) amongst selected shades and brands of three hybrid CAD/CAM blocks [GC Cerasmart (CS); Lava Ultimate (LU); Vita Enamic (VE)]. MATERIALS AND METHODS. The specimens (N = 225) were prepared into square-shaped ($12{\times}12mm^2$) with different thicknesses and shades. The measurements of color, translucency, and surface gloss were performed by a reflection spectrophotometer. The surface roughness and surface topography were assessed by white light interferometry. RESULTS. Results revealed that hue and chroma values were influenced by the material type, material shade, and material thickness (P < .001). The order of hue angle amongst the materials was LU > CS > VE, whereas the order of chroma was VE > CS > LU. $TP_{SCI}$ results demonstrated a significant difference in terms of material types and material thicknesses ($P{\leq}.001$). $TP_{SCI}$ values of the tested materials were ordered as LU > CS > VE. ${\Delta}E^*_{SCE-SCI}$ and $R_a$ results were significantly varied amongst the materials (P < .001) and amongst the shades (P < .05). The order of ${\Delta}E^*_{SCE-SCI}$ amongst the materials were as follows $LU>VE{\geq}CS$, whereas the order of $R_a$ was $CS{\geq}VE>LU$. CONCLUSION. Nano-ceramic and polymer-infiltrated-feldspathic ceramic-network CAD/CAM materials exhibited different optical, inherent color and surface parameters.

• Asian-Australasian Journal of Animal Sciences
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• 제20권6호
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• pp.887-893
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• 2007

Influences of forage DM and addition of cane molasses on silage characteristics of berseem (Trifolium alexandrium) and lucerne (Medicago sativa) and their ruminal digestion kinetics in Nili buffaloes were studied. Berseem and lucerne fodders (at one tenth bloom) were ensiled with wheat straw in laboratory silos to achieve 20, 30, 40% forage DM and without wheat straw (control); each forage DM level was supplemented with 2, 4 and 6% of cane molasses at ensiling. The pH and lactic acid contents of berseem and lucerne silages were affected by both forage DM and addition of molasses. Dry matter, CP and true protein (TP) of berseem and lucerne silages were affected by forage DM at ensiling but were not affected by the addition of cane molasses. Higher DM, CP and TP losses were observed when berseem and lucerne fodders were ensiled either without wheat straw or with wheat straw to achieve 20% and 40% forage DM at ensiling compared with 30% DM at ensiling. Fiber fractions (NDF, ADF, hemicellulose and cellulose) of berseem silage and lucerne silage were significantly increased with increasing forage DM at ensiling. Addition of cane molasses did not affect the DM, CP, TP and fiber fractions of both berseem and lucerne silages. Berseem and lucerne ensiled at 30% DM with 2% cane molasses were screened for comparative ruminal digestion kinetics with their respective fodders. Addition of wheat straw to berseem or lucerne fodder at ensiling depressed DM and NDF ruminal degradability. However, ruminal lag time, rate of degradation and extent of digestion of silages were similar to their respective fodders. In conclusion, berseem and lucerne could be ensiled with wheat straw to increase their DM to 30% along with 2% molasses for buffaloes.