• Journal of the Korean Wood Science and Technology
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• 제44권2호
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• pp.204-217
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• 2016

Modified poplar has emerged as a potential raw material for furniture production. Lack of specific modified poplar strength information; however, restricts applications in the furniture industry especially as related to strength in corner-joints. Optimization of strength in L-shaped corner dowel modified poplar joints under compression loads utilizing finite element analysis (FEA) by Taguchi method with the focus of this study. Four experiment factors (i.e., Structure Style, Tenon Length, Tenon Diameter, and Tenon Gap), each at three levels, were conducted by adopting a $L_9-3^4$ Taguchi orthodoxy array (OA) to determine the optimal combination of factors and levels for the von Mises stress utilizing ANSYS software. Results of Signal-to-Noise ratio (S/N) analysis and the analysis of variance (ANOVA) revealed the optimal L-shaped corner dowel joint in modified poplar is $45^{\circ}$ Bevel Butt in structure style, 24 mm in tenon length, 6 mm in tenon diameter, and 20 mm in tenon gap. Tenon length and tenon gap are determined to be significant design factors for affecting von Mises Stress. Confirmation tests with optimal levels and experimental test indicated the predicted optimal condition is comparable to the actual experimental optimal condition.

• 한국습지학회지
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• 제14권3호
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• pp.365-374
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• 2012

양돈 농가에서 구리, 아연 등의 성장촉진제와 항생제들이 사료 첨가제로 사용되는데 사료에 주입된 많은양이 분뇨로 배설되고 있다. 국내 양돈 폐수의 90% 이상이 퇴, 액비 형태로 농지에 적용되고 있는 상황에서 퇴,액비 내에 함유된 중금속과 항생물질은 토양에 흡착되어 농지에 잔류하거나 지하수나 지표수로 유출되어 수계로 빠져나간다. 농지에 살포된 중금속과 항생물질의 토양 내에서의 거동을 살펴보기 위해 실험실 기초 실험을 수행하였는데, Jar test와 칼럼 용출 실험을 수행하였다. 실험결과 아연의 86.4와 구리의 68%가 토양에 흡착되는 것으로 나타난 반면, 액비에 포함된 항생물질의 60% 이상은 칼럼 유출수로 용출되는 것으로 나타났다.

• 센서학회지
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• 제7권1호
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• pp.1-8
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• 1998

유한 요소법에 의한 수치 해석을 통하여 자기 트랜지스터(MAGFET)의 동작 특성을 분석하고, 소자의 최대감도를 얻기 위한 설계의 최적 조건을 제시하였다. 제시된 최적 조건에 따라 자기트랜지스터를 CMOS 표준 공정에 의하여 제작하고 전자기적 특성을 측정하였다. 소자의 감도는 활성 영역의 크기보다는 길이(L)에 대한 폭(W)의 비 W/L에 의존하며, W/L = 1 일 때 최대 감도를 나타내었다. 제작된 소자의 상대 감도는 2.53 %/T 이었다.

• 조명전기설비학회논문지
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• 제15권4호
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• pp.51-56
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• 2001

본 논문은 구조가 간단하고, 고속, 고정밀 위치결정이 가능하기 때문에 사무 자동화 및 공장자동화 시스템에 대한 적용이 급속히 확대되고 있는 선형직류모터의 로버스트 설계에 관하여 제안하였다. 로버스트 설계 방법은 다구찌 방법을 이용하였으며, 직교배열표를 이용하여 실험계획법을 수립하였다. 본 연구의 진행 과정은 먼저 중요 파라메터를 선정하였고, 다음으로 신호대 잡음(S/N)비를 적용하여 모터의 성능을 평가한 후, 변수의 최적 값을 결정하였다. 이 방법을 사용함으로써 짧은 시간 안에 로버스트 설계가 가능하였으며, 최종결과 모터의 성능이 향상됨을 알 수 있었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권4호
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• pp.49-59
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• 2017

This study estimated the nitrogen budget, including gaseous nitrogen oxides ($NO_x$), of South Korea in 2012~2014. The nitrogen budget was classified into three categories: agricultural and livestock, forest, and city. To estimate the nitrogen budget, several input and output parameters were investigated, including deposition, fixation, irrigation, chemical fertilizer use, compost, fuel, denitrification, volatilization, runoff, crop uptake, leaching, and $NO_x$ emissions. The annual nitrogen inputs from 2012 to 2014 were 6,202,828, 6,137,708, and 6,022,379 ton/yr, respectively. The corresponding annual nitrogen outputs were 1,393,763, 1,380,406, and 1,360,819 ton/yr, respectively, signifying a slight decrease from 2012 to 2014. $NO_x$ was the parameter contributing to the nitrogen budget to the greatest extent. The annual ratios of $NO_x$ emissions by vehicles, power plants, and businesses were 0.31, 0.31, and 0.30 in 2012, 2013, and 2014, respectively. A change in government policy that prohibited the disposal of livestock manure and sewage sludge in the ocean from 2012 affected nitrogen budget profile. As a result, the ocean disposal ratio completely diminished, which differs from previous studies.

• 한국물환경학회지
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• 제22권1호
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• pp.91-96
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• 2006

Many small scale Sewage Treatment Plants (STPs) are currently being constructed at many rural areas. The STPs in rural area suffer from low concentration and large inflow quantity fluctuation during wet weather mainly due to illicit combined sewer system. Sequencing Batch Reactor (SBR) is a process effectively coping with these obstacles. The main objective of this study was to evaluate SBR with high hydraulic loading and low inflow concentration. The operating conditions tested were: organic loading rate = $0.17-0.42KgBOD/m^3/d$, hydraulic loadings = $12.1-61.5m^3/m^2/d$, average MLSS concentration = 2500 mg/L, F/M ratio = 0.026-0.17 KgBOD/Kg MLSS, HRT = 9-12 hr HRT, and SRT = 5.6-33.6 days. Organic loading rate on SBR did not impact significantly on BOD and SS removal efficiencies. To increase treatment efficiencies, low hydraulic loading rate with low concentration was required. The results suggested that low influent concentration with high inflow rates during wet weather requires extended time for settling.

• Computers and Concrete
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• 제25권5호
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• pp.479-484
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• 2020

This work performed to analyses the impact of hooked end steel fibres on the mechanical properties of high performance concrete. The mechanical properties considered incorporate compressive strength, split tensile strength and flexural strength. Taking in to thought parameters, such as, volume fraction of fibres, fibre aspect ratio and grade of concrete, a logical strategy called Taguchi technique was utilized to discover the ideal blend of factors. L9 Orthogonal Array (OA) of Taguchi network comprising of three variables and three dimensions is utilized in this work. The evaluations of concrete considered were M60, M80 and M100. M60 contained 15% of metakaolin as bond swap though for M80 it was 5% of metakaolin and for M100 it was 10% metakaolin and 10% of silica smolder. The volume portion of fiber was fluctuated by 0.5%; 1% and 1.5% and the viewpoints proportions considered were 50, 60 and 80. The test outcomes demonstrate that incorporation of steel fibres enhance significantly the the strength characteristics of concrete, predominantly the splitting tensile strength and flexural strength. In light of relapse investigation of the test information scientific models were produced for compressive strength, split tensile strength and flexural strength of the steel fibre-reinforced high performance concrete.

• 한국양식학회지
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• 제17권2호
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• pp.151-157
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• 2004

Effects of supplementing selected fatty acids on fatty acid incorporation (17 days) , and progeny production (14 days) in Artemia franciscana (Great Salt Lake, USA) were studied. To compare with the control four diets, which differed in fatty acid composition alone contain Dunalieia tertiolecta and an emulsion either rich in OA (oleic acid, 18: 1 n-9), ARA (arachidonic acid, 20:4n-6), EPA (eicosapentaenoic acid,20:5n-3), or DHA (docosahexaenoic acid, 22:6n-3). Each of these emulsions was supplemented at a ratio of 20 % of the daily dose of D. tertiolecta (% algal dry weight). The initial OA and ARA values were 33.5 and 1.7 mg/g DW of freshly-hatched nauplii, respectively. After 11 days of feeding, these values increased to 38.8 and 7.6 mg/g DW in Artemia receiving the fatty acid sup-plement rich in each of the respective fatty acids. After 14 days, the levels were almost doubled, reaching 62.8 and 13.4 mg/g respectively. On EPA supplementation, its level after 11 days of feeding was 14.3 and 17.3 mg/g in male and female, respectively and was 16.0 and 23.1 mg/g in the male and female after 14 days, respectively. The EPA accumulated more in the body (39.1 mg/g) than in ovisac (16.9 mg/g). In the DHA supplementation group also, DHA levels after 11 days of feeding were 3.1 and 5.5 mg/g in male and female, respectively. After 14 days, the DHA level continued to increase in male. but slightly decreased to 4.6 mg/g in female. It was not richer in ovisac (2.6 mg/g) than in the remaining body of female (4.6 mg/g). In conclusion, fatty acids supplied by a lipid emulsion as a supplement to the algal diet are well incorporated in the adult Artemia. Apart from being an extra source of energy, these emulsions may function as source of HUFA which may play an essential role for growth and progeny production (fecundity) of Artemia.

• 한국환경과학회지
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• 제21권7호
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• pp.855-863
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• 2012

This study analyzed mass concentrations of TSP, PM10 and PM2.5 and elemental constituents according to the isentropic backward trajectories of air parcel from Cheongwonin East Asia during the period January - October, 2011. Mass concentrations of the continental polluted airflow (CP) showed levels of TSP and PM10 mass concentrations higher than the continental background airflow (CB). Also, PM2.5 mass concentrations of anthropogenic fine particles ran higher in CP than in CB. The elemental constituents and elemental constituent ratio ended up varying depending on the origin of atmospheric aerosols generated. The average absolute content of elemental constituents reached its height in CB, the ratio of anthropogenically originating elements (PE) among the all elements (AE) analyzed marked a high in CP, and Mg+Na/AE reached its height in the oceanic airflow (OA). At the same time, TSP, PM10 and PM2.5 mass concentrations, the ratio of PM2.5/TSP and PE/AE element ratio ran higher in CP than CB. Episodes of large-scale transport of atmospheric pollutants as observed at Cheongwon were 8 cases and 22 days. The ratios of PM10, PM2.5 among TSP mass concentrations showed different results and the ratios of PM2.5 showed an increasing trend in the episodes of anthropogenic air pollution transport. Overall, dustfall episodes show a level of elemental constituents higher than those of anthropogenic air pollution.Dustfall episodes were observed to contain more of Fe, Al and Ca originating from continental soils and those of air pollution were observed to contain more of Zn, Mn, Cu and Pb. By difference in contents of absolute elemental constituents, episodes of anthropogenic air pollution showed a high PE/AE rate, and dustfall episodes a high SE/AE rate.

• Journal of Oral Medicine and Pain
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• 제32권2호
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• pp.211-218
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• 2007

본 연구는 측두하악장애가 관절과 근육 등 다양한 구조물에 이환되는 복합적인 질환을 통칭하는 용어인 점을 고려하여 이환 구조물에 따라 세부 진단군으로 분류하여 최대교합력을 조사함으로써 진단에 따른 교합력의 차이 및 치료 전후의 교합력 변화를 평가하고자 하였다. 본 연구를 위하여 단국대학교 치과대학 부속병원 구강내과에 내원한 측두하악장애 환자 중 교합이 비교적 정상이고 치아상실이나 치주질환이 심하지 않은 편측성 증상과 징후를 환자 중에서 치료가 종결된 환자 36명 (남:여=7:29, 평균연령 $28.1{\pm}13.7$세)을 대상으로 하였다. 첫 내원시에 교합력측정기를 이용하여 이환측 및 비이환측의 견치와 제1대구치에서 최대교합력을 측정하여 비교한 다음, 치료가 종결된 상태에서 다시 한번 최대교합력을 측정, 비교하였다. 통계분석을 위해 paired t-test, ANOVA, multiple comparison t-tests를 사용하였다. 연구의 결과, 견치에서는 증상측과 비증상측 모두 치료 전에 비해 치료 후 최대교합력이 통계적으로 유의한 차이를 보이며 증가했으며,(p=0.001, p=0.000) 제1대구치에서는 증상측에서만 다소 증가된 경향을 보여주었다.(p=0.081) 치료전후의 최대교합력의 변화는 견치에서 뚜렷하게 나타났으나 측두하악장애를 이환 조직에 따라 저작근장애군, 관절내장증군, 관절염증군 및 골관절염군으로 나누어 비교했을 때 증상측 구치부에서 각 진단군간에 유의한 차이를 보여주었고,(p=0.023) 견치에서는 일부 군에서만 차이가 관찰되었다. 견치와 제1대구치 모두에서 골관절염군의 최대 교합력이 다른 군과 비교하여 가장 낮았는데, 이는 통증과 정형적 불안정이 교합력의 감소를 유발한다는 것을 알 수 있다. 치료전후의 차이는 저작근장애군과 관절내장증군에서는 증상측에서 유의하게 관찰된 반면, 골관절염군에서는 비증상측에서 유의하게 관찰되었다(p<0.05). 즉, 본 연구는 근육 또는 관절 기원의 통증, 기능이상, 정형적 불안정은 최대교합력의 감소를 야기하며 이는 보존적인 치료 후에 회복됨을 보여주는데, 치료 전후의 변화는 제1대구치보다 견치에서 뚜렷하게 나타났음을 시사한다.