• Journal of Advanced Marine Engineering and Technology
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• 제29권5호
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• pp.502-508
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• 2005

Fouling causes serious maintenance problems on heat exchanger tubes and process facilities. To avoid such fouling problems, numerous efforts have been tried. e.g., diagnosis of fouling, reducing and eliminating the fouling. etc.. The objective of the present study is to develop an innovative diagnostic system of fouling, which can detect the scaling attached to the wall non-homogeneously. The performance of the diagnostic system has been evaluated with a scaling simulator that generates scaling on tested tube wall. The measured values with the diagnostic system were compared with the amounts of the scaling generated by the simulator. In addition to, we showed the data that have been executed in field test for reliability verification.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.181-186
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• 2002

Fouling causes serious maintenance problems on heat exchanger tubes and process facilities. To avoid such fouling problems, numerous efforts have been tried, e.g., diagnosis of fouling, reducing and eliminating the fouling, etc.. The objective of the present study is to develop an innovative diagnostic system of fouling, which can detect the scaling attached to the wall non-homogeneously The performance of the diagnostic system has been evaluated with a scaling simulator that generates scaling on tested tube wall The measured values with the diagnostic system were compared with the amounts of the scaling generated by the simulator.

• 멤브레인
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• 제21권2호
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• pp.163-170
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• 2011

수처리 분리막 공정에서 막 오염 제어 기술은 현장 적용 기술 및 경제성 확보에 있어 매우 중요하다. 본 연구에서는 형광 나노 입자 및 형광 분광 분석법을 도입함으로써 수처리 분리막 공정에서 막 오염 정도를 실시간으로 측정 모니터링 할 수 있는 센싱 기술을 개발하고자 하였다. 막 오염 정도를 모니터링 할 수 있는 분리막 제조를 위해 세 종류의 형광물질 OB, FP, KCB를 담지한 다공성 polysulfone (PSf) 비대칭 막을 제조하였다. 형광 분광 분석 시스템을 이용하여 분리막 표면에서의 오염 정도를 실시간으로 측정한 결과, 형광 물질을 첨가한 막은 막 오염이 진행됨에 따라 형광 신호가 크게 감소함을 보여 막 표면 오염층의 모니터링 분석이 가능함을 확인하였다.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.121-126
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• 2010

An amperometric ascorbic acid selective sensor utilizing the transfer reaction of proton liberated from the dissociation of ascorbic acid in aqueous solution across an elliptic micro-hole water/organic gel interface is demonstrated. This redox inactive sensing platform offers an alternative way for the detection of ascorbic acid to avoid a fouling effect which is one of the major concerns in redox based sensing systems. The detection principle is simply measuring the current change with respect to the assisted transfer of protons by a proton selective ionophore (e.g., ETH 1778) across the micro-hole interface between the water and the polyvinylchloride-2-nitrophenyloctylether gel phase. The assisted transfer reaction of protons generated from ascorbic acid across the polarized micro-hole interface was first characterized using cyclic voltammetry. An improved sensitivity for the quantitative analysis of ascorbic acid was achieved using differential pulse stripping voltammetry with a linear response ranging from 1 to $100\;{\mu}M$ concentrations of ascorbic acid. As a demonstration, the developed sensor was applied for analyzing the content of vitamin-C in different types of commercial pharmaceutical tablets and syrups, and a satisfactory recovery from these samples were also obtained.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2021년도 하계학술대회
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• pp.283-285
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• 2021

본 논문에서는 수중에서 선박 하부에 붙은 오손생물(fouling organism)을 탐지하고 격자지도(grid map)로 나타내는 시스템을 제안한다. 제안하는 시스템은 소나(sound navigation and ranging: SONAR) 센서와 오손생물사이의 시간 데이터를 수집한 후, 라즈베리 파이 4(raspberry pi 4)에서 수집된 데이터를 이용해 격자지도에 맵핑(mapping)함으로써, 선저하부의 상태를 파악하는데 도움을 줄 수 있다. 본 논문에서는 제안된 지도 시스템을 이용하여 선박 하부에 붙은 오손생물의 분포를 확인할 수 있다.

• 상하수도학회지
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• 제28권2호
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• pp.161-170
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• 2014

It is essential to decrease energy consumption and excess sludge to economically operate sewage treatment plant. This becomes more important along with a ban on sea dumping and exhaustion of resource. Therefore, many researchers have been study on energy consumption reduction and strategies for minimization of excess sludge production from the activated sludge process. The aeration cost account for a high proportion of maintenance cost because sufficient air is necessary to keep nitrifying bacteria activity of which the oxygen affinity is inferior to that of heterotrophic bacteria. Also, additional costs are incurred to stabilize excess sludge and decrease the volume of sludge. There were anoxic, aerobic, membrane, deairation and concentration zone in this MBR process. Continuous aeration was provided to prevent membrane fouling in membrane zone and intermittent aeration was provided in aerobic zone through ammonia sensor. So, there was the minimum oxygen to remove $NH_4-N$ below limited quantity that could be eliminated in membrane zone. As the result of this control, energy consumption of aeration system declined by between 10.4 % and 19.1 %. Besides, we could maintain high MLSS concentration in concentration zone and this induced the microorganisms to be in starved condition. Consequentially, the amount of excess sludge decrease by about 15 %.

• 한국지구과학회지
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• 제26권2호
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• pp.129-136
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• 2005

Continued observation of ARGO floats for years(about 4 years) makes the conductivity sensor more vulnerable to fouling by marine life and associated drift in salinity measurements. In this paper, we address this issue by making use of floats deployed in different years. Floats deployed in the East Sea and the Indian Ocean are examined to find out float-to-float match-ups in such a way that an older float pops up simultaneously with a newer deployment (with tolerable space-time difference). A time difference of less than five days and space difference of less than 100km are considered for the match-up data sets. For analysis of the salinity drift under the stable water mass, observations of the floats from deepest water masses have been used. From the cross-check of ARGO floats in the East Sea and the Indian Ocean, it is found that there is a systematic drift in the older float compared to later deployments. All drift results, consistently show negative bias indicating the typical nature of drift from fouled sensors. However, the drift is much less than 0.01, the specified accuracy of ARGO program.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1474-1475
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• 2008

본 논문에서는 nanoporous Pt (Platinum) 전극을 이용한 무효소 혈당센서의 생체 적합성 및 전류응답 특성 향상을 위해 다양한 패키징 방법이 제안되었다. 생체적합성을 갖는 Nafion 멤브레인을 dipping, spin coating, chemical bonding 방법으로 패키징 한 후, 다양한 글루코오스 농도의 혈장, 전혈에서 특성을 분석, 비교하였다. 단백질 등이 포함되지 않은 환경에서 spin coating 방법으로 패키징한 센서의 전류응답 특성은 가장 좋았지만, 혈장 및 전혈에서는 dipping, chemical bonding 방법으로 패키징한 센서의 전류응답 특성에 미치지 못했다. Nafion film을 센서와 chemical bonding한 센서의 혈장에서 sensitivity 는 0.32 ${\mu}A/mM{\cdot}cm^2$ 이었다. 한편, 전혈에서 bare 센서가 급격한 bio-fouling 현상을 보이는 반면 패키징한 센서는 글루코오스 농도에 따라 일정한 전류변화를 보였다. 이는 Nafion을 이용하여 패키징한 무효소 혈당 센서가 생체환경에 적합할 뿐 아니라 생체이식형 및 연속 측정 가능한 시스템에 적용 가능함을 보여준다.

• 한국산학기술학회논문지
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• 제20권11호
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• pp.224-231
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• 2019

최근 지하수의 오염이 심각해지고 있다. 특히 축산농가 근처의 지하수 오염은 더욱 심해지고 있으며, 음용수로 마시기 어렵다. 그러나 일부 지역에서는 오염된 것을 알면서도 마시고 있다. 본 논문에서는 마을 공동우물에 설치할 수 있는 지하수 정수 장치를 설계 하였다. 설계된 지하수 정수 장치는 RO 멤브레인 필터를 사용하고, UV 살균을 통해 중금속, 박테리아, 유기화합물 등의 오염물질을 제거할 수 있게 하였다. 또한 원격 모니터링을 위해 전기 전도도, 압력, 유량 등의 센서를 부가하였다. 원격으로 모니터링하는 압력 및 유량 데이터로 RO 멤브레인 필터의 파울링 및 오염의 여부를 판단할 수 있으며, 급수의 전기전도도를 통해 유입되는 지하수의 오염 및 상태의 변동을 파악할 수 있다. 본 논문에서 설계된 지하수 정수 장치를 시골 농가에 설치하여 원격 모니터링 하였다. 15일간 지하수 정수 장치를 운영하고 모니터링 데이터를 분석한 결과, 생산수 유량은 평균 2.67L/min이고 급수의 압력 평균 7.09kgf/㎠로 RO 멤브레인 필터가 파울링 및 막힘없이 필터링되고 있음을 파악할 수 있었다. 또한 평균 전기전도도는 급수 796.6 uS/㎠이고 생산수 55.6uS/㎠로 일반적인 수돗물과 유사한 값을 나타내고 있어 주변에 오염원이 발생하지 않았음을 확인 할 수 있었다. 따라서 설계된 지하수 정수 장치는 원격 모니터링을 통해 필터의 교체 시점을 미리 확인할 수 있고, 지하수의 오염 여부에 대한 상태 확인이 가능하다.

• Ocean and Polar Research
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• 제42권3호
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• pp.195-210
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• 2020

The observed time series from the Korea Ocean Research Stations (KORS) in the Yellow and East China Seas (YECS) have various sources of noise, including bio-fouling on the underwater sensors, intermittent depletion of power, cable leakage, and interference between the sensors' signals. Besides these technical issues, intricate waves associated with background tidal currents tend to result in substantial oscillations in oceanic time series. Such technical and environmental issues require a regionally optimized automatic quality control (QC) procedure. Before the achievement of this ultimate goal, we examined the approach of the Ocean Observatories Initiative (OOI)'s standard QC to investigate whether this procedure is pertinent to the KORS. The OOI QC consists of three categorized tests of global/local range of data, temporal variation including spike and gradient, and sensor-related issues associated with its stuck and drift. These OOI QC algorithms have been applied to the water temperature time series from the Ieodo station, one of the KORS. Obvious outliers are flagged successfully by the global/local range checks and the spike check. Both stuck and drift checks barely detected sensor-related errors, owing to frequent sensor cleaning and maintenance. The gradient check, however, fails to flag the remained outliers that tend to stick together closely, as well as often tend to mark probably good data as wrong data, especially data characterized by considerable fluctuations near the thermocline. These results suggest that the gradient check might not be relevant to observations involving considerable natural fluctuations as well as technical issues. Our study highlights the necessity of a new algorithm such as a standard deviation-based outlier check using multiple moving windows to replace the gradient check and an additional algorithm of an inter-consistency check with a related variable to build a standard QC procedure for the KORS.