• Asian Journal of Atmospheric Environment
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• 제7권2호
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• pp.85-94
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• 2013

Methane concentrations have been monitored at the Anmyeon-do Observatory, Korea, since 1999. In recent years, the methane concentration has increased, but the sources of this increase have yet to be identified. This study was designed to identify the major source contributing to the increase by using World Data Centre for Greenhouse Gases (WDCGG) data and the Greenhouse Gases Emission Presumption (GEP) method. The data were collected at Anmyeon-do between 2003 and 2009 (except 2008), and the analyses showed that the increase in methane concentration originated mainly in rice paddies around the observation point. The annual average methane concentration at Anmyeon-do was 1894 ppb, of which 100-103 ppb (5.3-5.4%) was shown to originate mainly from rice paddies. The seasonal fluctuation in methane concentration from May to October estimated by the GEP method was compared with experimental data of previous research conducted on rice paddies. The close match obtained through this comparison shows that the GEP method is effective. The difference in methane concentration was also analyzed in terms of land use and land cover. It was shown that although rice paddies account for only 14.7% of the area surveyed, they accounted for between 69 and 90% of the total increase in methane concentration. These results confirm that rice paddies are the main source of the increase in methane concentration observed at Anmyeon-do.

• 센서학회지
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• 제23권1호
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• pp.58-65
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• 2014

We developed a low-cost automatic diagnosis system for water quality in cooling towers to measure the concentrations of key ingredients such as $Ca^{2+}$, $Cl^-$, $PO{_4}^{3-}$, and $Fe^{2+}$. $Ca^{2+}$, and $Cl^-$ are the main factors that cause the generation of scale, corrosion, and sludge in water pipes. $PO{_4}^{3-}$ prevents corrosion, sludge and scale by inhibiting the ions (i.e., $Ca^{2+}$, $Cl^-$) from sticking to the pipes. $Fe^{2+}$ is an indicator of pipe corrosion. The proposed system consists of a microprocessor, a specimen container and heater, a precision pump, relays and valves, LED optical sources, and photo detectors. It automatically collects water samples and carries out pretreatment for determining the concentration of each chemical, and then estimates the concentration of each ion using low-cost LED optical sources and detectors. Experimental results showed that the accuracy of the proposed system is sufficiently high for water quality diagnosis and management of cooling towers, demonstrating the possibility of the proposed system's wide usage in real environments.

• Safety and Health at Work
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• 제15권1호
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• pp.33-41
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• 2024

Background: Dust generated during the processing of building materials enterprises can pose a serious health risk. The study aimed to compare and analyze the results of ART and the Monte Carlo model for the dust exposure assessment in building materials enterprises, to derive the application scope of the two models. Methods: First, ART and the Monte Carlo model were used to assess the exposure to dust in each of the 15 building materials enterprises. Then, a comparative analysis of the exposure assessment results was conducted. Finally, the model factors were analyzed using correlation analysis and the scope of application of the models was determined. Results: The results show that ART is mainly influenced by four factors, namely, localized controls, segregation, dispersion, surface contamination, and fugitive emissions, and applies to scenarios where the workplace information of the building materials enterprises is specific and the average dust concentration is greater than or equal to 1.5 mg/m³. The Monte Carlo model is mainly influenced by the dust concentration in the workplace of building materials enterprises and is suitable for scenarios where the dust concentration in the workplace of the building materials enterprises is relatively uniform and the average dust concentration is less than or equal to 6mg/m³. Conclusion: ART is most accurate when workplace information is specific and average dust concentration is > 1.5 mg/m³; whereas, The Monte Carlo model is the best when dust concentration is homogeneous and average dust concentration is < 6 mg/m³.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.314-314
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• 2016

In this paper, the effects of carrier concentration on dielectric constant of ITO films were investigated by spectroscopic ellipsometry. From SE results, we find the pronounced shift of the ${\varepsilon}1$ peaks toward high energy with concentration; while contrarily, the ${\varepsilon}2$ values at low energy region increases with decreasing concentration. These shifts are attributed to the Burstein-Moss and free-carrier absorption effects within ITO films. With increases carrier concentration, the values of extinction coefficients show quite different behaviors in range of wavelength from 200 to 1200 nm. The reduction in k at ${\lambda}{\leq}500nm$, while increasing at ${\lambda}{\geq}500nm$ was observed. The QE of HJ solar cells behaviors can be roughly classified into two regions: short-wavelengths (${\leq}650nm$) and long-wavelengths region (${\geq}650nm$). With increasing carrier concentration as well as energy band gap, QE shows improvement at short-wavelength, while at long-wavelength QE shows opposite trend. Widening band gap energy due to Burstein-Moss shift is the key to improve QE in short-wavelength; simultaneously FCA effect due to optical scattering is attributed to the reduction in QE at long-wavelength. In spite of band gap extension, Jsc calculated from QE decreases from 34.7 mA/cm2 to 33.2 mA/cm2 with increasing carrier concentration. It demonstrated that FCA effect may more govern Jsc in the HJ solar cells.

• 전자공학회논문지
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• 제50권12호
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• pp.254-260
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• 2013

뇌전도 분석에 의한 제어신호의 검출은 다양한 분야에 활용될 수 있다. 다채널 뇌파 연구는 측정 시스템이 복잡해지고 착용이 불편해진다는 단점이 있어서 본 논문에서는 실용적인 응용을 우선으로 하였고 단 채널 기반으로 집중에 의한 on/off 제어 신호를 신뢰성 있게 검출할 수 있는 방법을 연구하였다. 평상시 휴식 상태와 집중하였을 때의 알파, 베타 및 세타파의 대역 신호를 분석하였으며 이 때 파워스펙트럼과 히스토그램에서의 차이를 검출하였다. 세타파를 이용하였을 때 보다 베타/세타를 이용해 집중력 검출을 하는 것이 더 좋은 결과를 나타내었다. 세타파만을 이용하였을 때보다 평균 검출 시간이 단축되었으며 또한 집중 전 휴식시간이 길어질수록 검출 성공률이 낮아지며, 검출 시간도 상대적으로 길어졌다. 휴식시간 10초의 경우 개인마다 검출 성능의 차이는 있었지만 평균 91%의 검출 성공률과 검출 시간은 평균 20.2초의 결과를 얻었다.

• 대한환경공학회지
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• 제39권8호
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• pp.441-448
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• 2017

본 연구에서는 미세기포를 산란체로 사용한 편광산란 측정법을 이용하여 수중 계면활성제의 농도를 측정하는 방법을 개발하였다. Mueller 요소 $M_{11}$은 계면활성제의 농도가 0 ppm부터 60 ppm 사이 영역에서 농도와 선형적인 비례관계를 가져 계면활성제 농도를 측정할 수 있는 유용한 파라메터로 사용될 수 있음을 알았다. 이 측정은 산란각이 150도, 소광비가 56.2 조건에서 가장 효과적 이였다. 이 연구 결과를 볼 때, 편광산란 측정법(EPLS)은 강이나 호수에서 수질을 실시간적으로 모니터하는데 있어 충분히 효과적인 수단으로 보인다.

• 한국컴퓨터정보학회논문지
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• 제17권4호
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• pp.59-65
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• 2012

고추는 건조과정에서 부패되거나 색이변하는 경우가 발생하므로 건고추 품질을 높이기위해서는 건고추를 선별 할 수 있는 기법이 필요하다. 독립성분분석은 블라인드소스분리에서 가장 널리 사용되는 방법으로 이 기법을 사용하여 건조시킨 고추 영상에서 가장 중요한 성분에 대한 농축영상을 얻는다. 취득한 농축영상은 일반 이진(BW) 영상과 달리 주요 성분만 반영한 것으로 영상의 주요 성분 분포 상태를 알 수 있으며 품질을 판단하여 선별하는 것이 가능하다. 또한, 추출된 농축영상의 크기는 고추의 매운 맛을 내는 주요 성분인 캡사이신류의 양과 관련성이 있음을 알 수 있다. ICA 독립성분을 기반으로 한 농축영상 추출을 통해 고추 건조과정에서 부패되어 색상이 좋지 않거나 캡사이신류과 같은 주요 성분이 없게 된 고추를 선별해하는 방법을 제안한다.

• 국제물리치료학회지
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• 제1권2호
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• pp.155-161
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• 2010

Purpose: The purpose of this study was to estimate the effects of subliminal music with balance imagery training on balance and concentration. Methods: The participants were 45 seniors in an undergraduate school in Korea. The subliminal music with balance imagery training intervention was carried out for 20 minutes. Other interventions were also carried out for 20 minutes. 12 seniors(Group A) listened to subliminal music with balance imagery training, 12 seniors(Group B) listened to subliminal music, 11 seniors(Group C) received balance imagery training, and 10 seniors(Group D) had no intervention(Control group). The grid test is related to measured levels of concentration intensity. Romberg one legged standing test was carried out for 30 seconds. The collected data was analyzed by one-paired t test and one way ANOVA using the SPSS Windows 12 ver. program. Results: The major findings of this study were as follows: Concentration levels of Group A and C improved, and balance levels of Group C and D improved. There was a statistically significant decrease in concentration between Group A and B, Group A and C after intervention. Conclusion: These findings suggest that listening to subliminal music with balance imagery training may be useful in managing concentration in seniors. So it provides basic information for further concentration on improving education on music with balance imagery training.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.209-216
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• 2016

Holes of rivets, bolts and nuts may cause stress concentration on the plates used in aircraft, ship and other structures. Excessive stress concentration may lead to severe breakage of the plates. Thus, accurate analysis of the stress concentration at the design stage will be important. In this paper, accuracy of EDISON program in stress concentration analysis was examined. By changing hole size on a narrow plate, the change of the stress concentration factor(K) was investigated. Additionally, the same experiment was conducted about series of holes on plate to investigate the interaction between adjacent holes. Then, these numerical results were compared with the analytic prediction. EDISON program showed very high accuracy about stress concentration, since the numerical results was correlated well with the analytic prediction.

• 한국정보전자통신기술학회논문지
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• 제16권6호
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• pp.540-546
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• 2023

IoT는 관련 기술의 발전으로 인해 사용범위가 넓어졌으며 다양한 서비스의 구현을 위한 수요를 충족하기 위해 다양한 센서가 개발되고 보급되었다. 센서를 이용한 알코올 농도의 측정은 음주운전 방지에 활용할 수 있으며 이를 가능하게하기 위해서는 정확한 알코올 농도를 측정하고 스마트폰에서 서버로 안전한 전송을 보장하여야 한다. 또한 측정한 알코올 농도 값을 음주 수준을 판단하는 기준값으로 변환하는 과정이 필요하다. 본 논문에서는 센서를 사용하여 알코올 탐지기술을 적용한 음주측정기기에서 수집한 알코올 농도 정보를 보정 알고리즘을 통해 수치를 변환하고 원격지에 위치한 서버에 안전하게 전송하고 관리하는 시스템을 제안하고 구현한다. 원격지 서버와의 보안은 네트워크 계층의 SSL을 적용하여 데이터의 무결성과 기밀성을 보장하도록 하였으며 서버는 수신된 정보를 암호화하여 데이터베이스에 저장하여 추가적인 보안을 제공하도록 하였다. 알코올 농도 측정의 정확성, 통신의 효율성을 분석한 결과 에러 허용치 내에서 측정되고 전송되는 것을 확인하였다.