• 충청수학회지
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• 제10권1호
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• pp.43-56
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• 1997

In this paper, we introduce a new class of ${\delta}$-frames and study its properties. To do so, we introduce ${\delta}$-filters, almost Lindel$\ddot{o}$f frames and Lindel$\ddot{o}$f frames. First, we show that a complete chain or a complete Boolean algebra is a ${\delta}$-frame. Next, we show that a ${\delta}$-frame L is almost Lindel$\ddot{o}$f iff for any ${\delta}$-filter F in L, ${\vee}\{x^*\;:\;x{\in}F\}{\neq}e$. Last, we show that every regular Lindelof ${\delta}$-frame is normal and a Lindel$\ddot{o}$f ${\delta}$-frame is preserved under a ${\delta}$-isomorphism which is dense and codense.

• 멤브레인
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• 제12권1호
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• pp.21-27
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• 2002

본 연구에서는 회분여과방식을 이용하여 부하율에 따라 생성되는 생물대사성분의 특성 및 분포를 관찰하였다. 실험에 사용된 기질은 단일 탄소인 phenol을 사용하였으며, 분자량 분포실험을 위하여 분자량이 각각 30K, 100K Dalton 및 $0.45{\mu}$ membrane filter를 이용하여 구하였다. 페놀농도가 120, 230 및 440 mg/L 일 때 비기질이용율(q)은 각각 0.639, 1.281, 1.744 (mgTOC/mg MLSS/day)로 나타났으며 Run C일 때 가장 높은 이용율을 나타냈다 . 내생단계에서 미생물의 사멸율($K_d$)는 각각 0.0536, 0.0661, 0.0749($day^1$)이며 생성계수 ($SMP_e$) 는 각각 0.006, 0.0058, 0.0057($day^1$)로 나타났다. 초기 유입된 기질이 기질분해에 의해 생성된 $SMP_s$로 분해되어지며, 시간경과에 따라 $SMP_{nd}$ 로 진행됨을 알수 있었다. 기질분해 완료 후 미생물의 내생단계에 접어들면서 $SMP_e$성분으로 전환되었다. 유입부하율에 따른 분자량 분포 측정결과는 운전시간이 경고함에 따라 점차 저분자 물질이 고분자의 난분해성 물질로 전환되었다.

• 한국통신학회논문지
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• 제16권9호
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• pp.862-876
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• 1991

본 논문에서는 N-선로 결합 구조의 등가 이미턴스 산출식을 N-선로 결합시스템의 normal mode 정수로 표현하였다 제안한 산출식은 다양한 결합 구조 즉 방향성 결합기, DC 블럭, 대역통과/대역소거 여파기 및 기타 균일하게 결합된 형태인 여파기 등에 이용될 수 있도록 일반화 되었으며 이들 계산식은 준-TEM 모드로 가정한 결과이다. 이를 이용하여 임의의 임피던스로 종단한 일반적인 4-포트 결합 선로에서 정의된 산란정수를 구하여 입, 출력 포트에 접속된 임피던스에 정합시키는 최척 선로 규격을 구하는 과정을 제시하였다. 제시된 방법을 적용하여 복수 마이크로스트립 결합 선로인 3-선 2-포트 대역소거 여파기의 주파수 특성을 기존의 방법과 비교하여 일치함을 확인하고 5-선 4-포트 구조를 테프론(비유전율 $e$r=2.55) 기판(두께 h=1.588mm) 에 중심 주파수 4 GHz로 설계하였다. 설계 수치에 따른 회로를 제작하여 측정한 실험 결과는 설계시 얻어진 주파수 특성 이론치에 근접하였다.

• 한국물환경학회지
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• 제21권2호
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• pp.190-195
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• 2005

The laboratory and pilot scale BAFs (biological aerated filters) were operated with 0.3 hr to 1.1 hr EBCT(empty bed contact time) at a maximum filtration rate of $472m^3/m^2/day$ as a treatment method for reuse of secondary effluent and by-pass flow in this study. The effluent BOD and SS were generally 3.5 to 5 mg/L and 2 to 3 mg/L, respectively with 2ndary effluent, but the SS concentrations increased to 4 to 8 mg/L with the increased flow rates of by-pass flow. Potential nitrification rates were very high, but the nitrogen removal efficiencies were low due to the limited carbon sources. Bypass of a part of primary effluent seemed to be desirable to increase the nitrogen removal. Disinfection must be furnished for the reuse of BAF effluent.

• 대한의용생체공학회:의공학회지
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• 제6권1호
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• pp.5-12
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• 1985

In this paper Kalman filtering technique is applied to ultrasound signal to improve resolution capability, Ivhlch is in use of diagnostic imaging systems. The main advantage of Kalman filter algorithm for the analysis of reflected ultrasound signal is its recursive structure which can be easily adapted to tlme varing system. Because soft-tissues, such as liver, act as distributed acoustic low-pass filters which continually change the propagating pulse. tIne can put to practical use above advantage to find a suitable signal generallng model. In state-space description of the system, the 6th order system produces tl)e 1)esc spectral approximation to the source pulse As a result of spectrum analysis, 6th order estimator for two closely spaced ((p.5 mm) reflectors enhances resolution by 4dB-lOdB. By using this result, the possibility to detect even minute tumor is demonstrated.

• 상하수도학회지
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• 제28권6호
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• pp.725-733
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• 2014

16 water treatment plants(WTPs) in Jeju province were investigated to evaluate the corrosivity of tap water. In addition, the impacts of lime and carbon dioxide on LI changes at ES WTP were analyzed. The average of LI in Jeju tap was -1.78 which was similar to that of in-land multi-regional WTPs. The recommended process to improve LI of ES WTP which has high corrosivity(i.e., LI = -2.61) was to combine lime and carbon dioxide with the dosages of 20 mg/L and 5 mg/L respectively to meet LI of -1.0 ~ 0. pH was confirmed to be a major water quality parameter that determined LI based on the correlation results among LI and water quality parameters. Precaution on turbidity increase by lime addition should given to minimize particle breakthrough in the distribution system. Turbidity increase can be controlled by the addition of lime prior to filters.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.544-558
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• 2013

This paper proposes a simplified and efficient control scheme for Unified Power Quality Conditioner (UPQC) based on three-level (NPC) inverter capable to mitigate source current harmonics and compensate all voltage disturbances perturbations such us, voltage sags, swells, unbalances and harmonics. The UPQC is designed by the integration of series and shunt active filters (AFs) sharing a common dc bus capacitor. The dc voltage is maintained constant using proportional integral voltage controller. The shunt and series AF are designed using a three-phase three-level (NPC) inverter. The synchronous reference frame (SRF) theory is used to get the reference signals for shunt and the power reactive theory (PQ) for a series APFs. The reference signals for the shunt and series APF are derived from the control algorithm and sensed signals are injected in tow controllers to generate switching signals for series and shunt APFs. The performance of proposed UPQC system is evaluated in terms of power factor correction and mitigation of voltage, current harmonics and all voltage disturbances compensation in three-phase, three-wire power system using MATLAB-Simulink software and SimPowerSystem Toolbox. The simulation results demonstrate that the proposed UPQC system can improve the power quality at the common connection point of the non-linear load.

• 한국토양비료학회지
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• 제29권2호
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• pp.137-144
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• 1996

소규모(小規模) 축산농가(畜産農家)에서 배출(排出)되는 돼지(돈(豚))분뇨폐수(糞尿廢水)를 처리(處理)함과 동시(同時)에 재활용(再活用)할 수 있는 방법(方法)을 찾기 위하여 볏짚을 살수여상법(撒水濾床法)의 충전재(充塡材)로 사용(使用)하였다. 폐수처리후(廢水處理後) 볏짚을 부숙(腐熟), 건조(乾燥), 분쇄(粉碎)하여 토양(土壤)에 첨가(添加)한 후(後) 오그라기 상치를 재배(栽培)한 결과(結果)는 다음과 같다. 1. 농가퇴비(農家堆肥)에 비(比)해 부숙(腐熟)된 짚을 처리(處理)했을 시(時) 수량지수(收量指數)가 월등(越等)히 높았으며 N.P.K. 기본(基本) 시비(施肥)에 부숙(腐熟)된 짚 1750 kg/10a로 시용(施用)했을 때 수량지수(收量指數)가 가장 높았다. 2. 부숙(腐熟)된 짚을 시용(施用)한 토양(土壤)의 화학적(化學的)인 성질(性質) 중(中) pH, T-N, ava.P2O5, OM, 그리고 Ex.K, Ca, Mg이 증가(增加)했는데 반(反)하여 CEC은 본래(本來)의 값으로 귀착(歸着)되는 경향(傾向)이었다. 3. 짚을 살수여상법(撒水濾床法)의 충전재(充塡材)로 사용(使用)했을 경우(境遇)의 BOD, COD, SS의 제거(除去) 효율(效率)이 통상적(通常的)인 충전재(充塡材)와 별(別) 차이(差異)가 없었다.

• 한국환경보건학회지
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• 제34권1호
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• pp.86-94
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• 2008

Lake Shiwha, an artificial lake located near metropolitan Seoul, offers a unique water environment and has been suspected to have high levels of chemical and microbiological contaminations. Lake Shiwha was originally connected to the sea but currently has four major surface water inputs from agricultural, municipal, industrial areas and in addition an occasional inflow from the sea. The objectives of this study are to investigate the relative contribution of microbial contaminants from each of the inflowing surface waters and to identify appropriate microbial indicator organisms in this unique water environment. We measured the levels of microbial contaminations in the four inflowing surface waters. A number of microbial indicator organisms including total coliform (TC), fecal coliform (FC), E. coli, Enterococci, somatic and male-specific coliphages were analyzed. Bacterial indicator microorganisms were detected and quantified by the $Colilert^{(R)},\;Enterolert^{(R)}$ kit. Surface water (50 l) was sampled by $ViroCap^{TM}\;5"$ cartridge filters and analyzed by the single agar layer method for detecting coliphages. The concentrations of TC, FC, E. coli, and Enterococci were 1543 CFU/100 ml${\sim}1.99{\times}10^6$ CFU/100 ml, 0 CFU/100 ml${\sim}202$ CFU/100ml, 0 CFU/100 ml${\sim}1.80{\sim}10^5$ CFU/100ml, 74 CFU/100 ml${\sim}3408$ CFU/100 ml, respectively. The male-specific and somatic coliphages were detected in three different inflowing surface waters. Isolated E. coli and Enterococci strains were further analyzed by 16s rDNA amplification and subsequent phylogenetic analysis from Jungwang-chun, Ansan-chun, Banwol-chun and penstock of inflowing surface water. Our results indicated that the concentrations of different fecal indicator microorganisms might not be highly correlated with each other. Multiple microbial indicator organisms should be used for monitoring microbial contamination and microbial source tracking methods.

• 한국토양비료학회지
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• 제29권4호
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• pp.371-377
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• 1996

소규모(小規模) 돼지사육농가(飼育農家)에서 배출(排出)되는 축산폐수(畜産廢水)를 효율적(效率的)으로 처리(處理)함과 동시(同時)에 재활용(再活用)할 수 있는 방도(方途)로서 볏짚을 살수여상처리충전재(撒水濾床處理充塡材)로 사용(使用)하였다. 폐수처리(廢水處理) 후(後) 볏짚을 건조(乾燥) 분쇄(粉碎)하여 토양(土壤)에 첨가(添加)한 후(後) 오그라기 상추를 재배(栽培)한 결과(結果)는 다음과 같다. 1. 일반적(一般的)인 농가퇴비(農家堆肥)에 비해 살수여상처리충전재(撒水濾床處理充塡材)로 사용된 짚의 시용에 따른 수량지수(數量指數)가 월등(越等)하게 높았다. 기본시비(基本施肥)(N.P.K.)에 처리(處理)된 짚 700kg/10a에서부터 2100kg/10a에 이르기까지 계속수량지수(繼續數量指數)가 향상(向上)되었다. 2. 짚의 시용(施用)이 토양(土壤) pH 값을 상승(上昇)시키는 효과(效果)가 있었음에 반(反)해 T-N, Avail $P_2O_5$, OM, 그리고 CEC에는 별영향(別影響)이 없었고 치환성(置換性) K와 Ca의 함량(含量)은 증가(增加)했으나 치환성(置換性) Mg의 잔류량(殘留量)은 감소(減少) 했다. 따라서 토양비옥도(土壤肥沃度)의 유지(維持)를 위(爲)해서는 Mg의 보충(補充)이 필요(必要)하였다 3. 살수여상처리충전재(撒水濾床處理充塡材)로 사용(使用)된 짚은 BOD, COD, 그리고 SS를 제거(除去)하는 효율면(效率面)에서 통상적(通常的)인 충전재(充塡材)와 별차이(別差異)가 없었다.