• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.592-598
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• 2008

In this paper, a novel pilot-aided integer frequency offset estimation scheme is proposed for orthogonal Sequency division multiplexing (OFDM)-based digital video broadcasting (DVB) systems. The conventional pilot-aided integer frequency offset estimation scheme proposed for OFDM-based DVB systems exploits the partial information of combinations provided by pilots. Thus, in this paper, we propose a novel integer frequency offset estimation scheme exploiting all information of pilot combinations. To compare the performance of the proposed scheme with that of the conventional scheme, we conduct a simulation in additive white Gaussian noise (AWGN) and multipath Rayleigh channels, which shows that the proposed scheme outperforms the conventional scheme in terms of the probability of integer frequency offset estimation failure.

• Journal of IKEEE
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• v.6 no.2 s.11
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• pp.146-151
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• 2002

This paper proposes a method that regulate a chlorine density to real time using RTOS. The most of a cleaning bed make use of the flux method to input chlorine. But, This method is difficult to control of chlorine's amount because Amount used of water is difference in each time or according to season. In this paper, we have designed a two method to flux and remain chlorine. Each task is programmed to cope with changeable external environment. The efficiency of the proposed system is shown by comparison results for performance of the proposal system with cleaning bed using a flux method.

• Membrane Journal
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• v.8 no.4
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• pp.220-227
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• 1998

Recent data from Environmental department show that some out of 2,000 places surveyed are contaminated by nitrate, ammonia, fluoride, chloride and so forth in excess of the environmental standard-including purification plants, water taps, small water supply systems. In this study, some items which exceed drinking water standard were chosen and their concentrations were made varying from around standard level to around detected maximum concentration. After they permeated through the membrane module sold in the domestic market and made for household water-purifier, the most suitable membranes were selected according to individual water quality of various regions. In addition, the bacterial growth after storage for various days and under various temperatures was examined for the purpose of the effect of the time and temperature on bacterial growth.

• Korea Petroleum Association Journal
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• no.4 s.50
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• pp.46-52
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• 1985

• The Korea Swine Journal
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• v.17 no.6 s.190
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• pp.145-147
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• 1995

• The Monthly Technology and Standards
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• s.40
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• pp.21-24
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• 2005

• Korea Petroleum Association Journal
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• no.7 s.137
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• pp.28-33
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• 1992

• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.469-476
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• 2010

The purpose of the study is to find ways to decrease turbidity and residual aluminum by improving the efficiency of coagulation process through controlling the pH of the source water with $CO_2$ when the pH increases by algal bloom or by the characteristics of the source water. Water quality parameters were monitored before and after $CO_2$ addition in February, March, April, and December, when the pH of the source water is over 8.0 and constant regardless of day and night. Water quality parameters closely related with evaluation of treated drinking water quality were monitored in detail, e.g. aluminum, turbidity, particle counts, TOC, THMs, 2-MIB, and geosmin. According to the results, inorganic water quality parameters such as turbidity, particle counts, and aluminum were decreased due to improved efficiency of the coagulation process. It was concluded that the pH of the water in the arrival basin must be controlled below 7.4 by adding $CO_2$ when the pH of the source water increasing. By controlling pH with $CO_2$, the water quality could be maintained within the drinking water quality goal of Seoul City (<30 particle/mL of particle count, <0.05 NTU of turbidity and <0.02 mg/L of aluminum). The change of the pH could not affect the concentrations of DBP's (e.g., THMs, CH, and HAAs) and taste/odor causing compounds (e.g., 2-MIB and geosmin). 2-MIB and geosmin were affected more by their initial concentrations in the source water.

• Journal of Environmental Health Sciences
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• v.20 no.2
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• pp.1-13
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• 1994

I. 서론 : 음용수 중의 악취 발생사건은 오염 수돗물에 의한 피해지역이 광범위할 뿐만 아니라 사건발생 즉시 해당 정수장에서 적절히 대처하지 못할 경우 악취 수돗물에 의한 주민의 불안감은 크다고 하겠다. 뿐만 아니라 악취 오염물질을 규명하는 노력이 환경과학 및 환경공학의 체계적이고 구체적인 밑받침이 없이 이루어질 경우 원인물질을 잘못 규정하는 등 구체적인 방향성을 상실하게 되어 많은 수돗물 사용 시민의 음용수 관련행정에 대한 우려와 불신을 증폭시키게 된다. 따라서 음용수의 냄새생성 원인을 규명하고 악취 발생시 정수장 근무자들의 비상 대처방안을 마련하는 것이 시급하다고 하겠다. 본 글에서는 음용수 오염과 관련하여 악취발생의 원인을 발생일자별로 구분하고 그 대처방안에 대하여 검토하였다.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.478-485
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• 2008

고객 만족과 납기 충족율을 최대화하기 위하여, 정확하고 실용적인 납기회답 시스템(ATP)은 매우 중요한 역할을 한다. 그러나 복잡한 공급사슬관리 환경 하에서 조달, 제조, 분배 등을 모두 고려한 정확한 ATP 수량 할당은 매우 어려운 업무이고, 때문에 많은 연구들이 이루어져 왔다. 지금까지 기존의 선행 연구에서 시도되었던 ATP 모형들은 공통적으로 정수배의 시간 단위만 고려해 왔고, 이는 실제 산업 현장의 ATP 프로세스를 정확하게 반영하지 못하고 있는 비현실적인 가정이라 할 수 있다. 본 논문에서는 SCM을 위하여 비정수 타임 랙을 사용한 ATP 시스템을 고려한다. 기존 연구들에서 이산형의 무리한 가정으로 표현되어 왔던 시간 단위를 동적 생산 함수(dynamic production function) 개념을 통하여 비음의 실수 범위에서의 자유롭게 나누어 고려할 수 있도록 하였다. 이를 통하여 기존 ATP 연구들의 무리한 가정을 제거하였으며, 보다 더 현실에 가까운 ATP 모델을 제안한다. 본 논문에서는 특히 공급 사슬(Supply Chain) 전체의 재고와 생산, 운송을 모두 고려하며 고객 주문에 대응하는 통합 ATP 시스템을 설계하였고, 기존 연구들이 미처 고려하지 못한 시간 흐름의 연속성에 중점을 두고 선형 계획(LP) 문제의 형태로 비정수 타임랙(non-integer time lag)을 갖는 ATP 시스템을 모델링하였다.