• 상하수도학회지
• /
• 제25권4호
• /
• pp.489-495
• /
• 2011

Silt Density Index (SDI) has been used as a fouling index for reverse osmosis (RO) processes for decades. In order to decrease RO fouling, feed water should meet SDI standard, which was used to select a proper pretreatment system for RO processes. However, SDI is supposed to be sensitive only to particles larger than 0.45 ${\mu}m$ in terms of diameters while nanoparticles and dissolved organic matter can be potent foulants for RO processes. Our study started from the suspected performance of SDI as a RO fouling index. SDI data from pilot plants located world wide including South Korea were collected and analyzed. Suspended partcle concentration (i.e., turbidity and particle counts), and dissolved organic matter concentration (i.e., dissolved orgnaic carbon (DOC) concentration) data were also collected and compared to SDI values of same water samples. We found that SDI values were not only affected by suspended particle concentration but also by dissolved organic matter concentration. Therefore SDI can be used as a reasonable fouling index for RO feed water because the main foulants for RO processes are suspended particle and dissolved organic matter.

• Journal of Astronomy and Space Sciences
• /
• 제9권1호
• /
• pp.69-88
• /
• 1992

전파 전파에 있어서 전리층의 영향은 산란, 감쇄, 각오차, 위치오차, 및 시간 지연등이다. 적당한 전리층 조건 아래서 하전입자는 전파로 부터 에너지르 뺏어 전파 감쇄의 원인이 되게 한다. 또한 전자밀도가 균일하지 않은 경로를 따라 전파가 전파되는 경우, 전파 방향, 위치, 전파 시간등에 변화가 생기게 된다. 본 논문에서는 1985년 1월 부터 1989년 10월까지 전파연구소에서 관측된 국내 전리층 관측자료를 토대로 Chapman법칙에 따른 전리층 모델을 정립 하였으며, 이로부터 전파 전파에 있어서 각 오차, 위치 오차, 시간 지연, 및 감쇄등을 주파수와 위성의 고도에 따라 고찰하여 보았다.

• 한국식품영양과학회지
• /
• 제20권6호
• /
• pp.603-608
• /
• 1991

고추의 효율적인 이용의 방안으로서 고추 oleoresin추출조건의 구명(究明)과 저장중인 품질변화에 대해서 실험하였다. 고추 oleoresin의 최적 추출용 매로는 사용한 8가지 용매중에서 acetone이 가장 좋았으며, 분쇄한 건조고추의 입자크기는 100 mesh, 시료중량에 대한 용매의 혼합비율은 1 : 3(w/w) 및 추출온도는 $25^{\circ}C$에서 가장 효과적으로 추출되었다. 추출수율을 기준으로 적정 추출시간은 5시간이였으며, 이상의 최적 추출조건에서의 oleoresin 수율은 18.7%였다.

• 한국환경과학회지
• /
• 제11권10호
• /
• pp.1081-1087
• /
• 2002

This study was performed to research the characteristics of suspended particulate for Yellow Sand of January, 1999 in Busan. Yellow Sand frequency during 13 years(1988~2000) in Busan showed maximum in April(57%), next to March(21%), May(16%). According to result of 850hPa weather map and backward isentropic trajectory, this event originated from the Gobi Desert and the Loess Plateau of China. And three mode was found in time series of TSP and PM10 concentration, primary peak showed the maximum hourly concentration at ali station. Gamjeondong as industrial site showed the highest TSP concentration and also had the longest high concentration($geq700\mu\textrm{g}/m^3$). In PM10, concentration of primary peak showed maximum value at Yeonsandong, maximum concentration of secondary and third peak was Deokcheondong. Lasted time from primary peak to secondary peak was about 30 hours, between secondary peak and third peak was 18 hours in Busan, The traveling time between occurrence of Yellow Sand the finding of it was 8~9 hours in Busan and 4~5 hours in central area.

• 한국환경과학회지
• /
• 제11권7호
• /
• pp.705-711
• /
• 2002

In order to determine the factors causing Microcystis spp. bloom in the lower Nakdong River (Mulgum), we prepared wide ranges of pH, nutrient(N, P) concentration and the light through an enclosure experiment far 10days (pH gradient. 6.5, 7.5, 8.5, 9.5; gradient of N, P: ${\frac{1}{2}}DW+{\frac{1}{2}}River$ Water (RW), RW only; four different levels of nutrient addition/day; light: 100, 85, 60, 30, 15% of full sun light). From three days, the difference of Microcystis density in each enclosures was observed. The high density of Microcystis was maintained in the treatments over pH 9.5 and 85% of full sun light. However, in all nutrient treatments, relatively lower cell density than that of pH and light treatments was observed. These results suggested that pH and light input may play more important roles than nutrients in the early development of Microcystis bloom in the eutrophic lower Nakdong River.

• 상하수도학회지
• /
• 제20권6호
• /
• pp.905-910
• /
• 2006

In order to evaluate the optimum operation condition of ozonation to minimize bromate formation, based on the NOM characteristics of raw waters, the pathway of bromate formation by ozonation in domestic raw waters was investigated. Considering the bromate formation reactions, the fractions of bromate formation from bromide by OH radical and molecular ozone were calculated with measured values of ozone decay rate ($k_c$) and Rct. The results showed that molecular ozone is more important role in the formation of bromate in domestic raw waters than OH radical. The ratio of bromide oxidation reaction by molecular ozone ranged 73~88%. Fractions of $HOBr/OBr^-$ reaction with both molecular ozone and OH radical were also determined. OH radical reaction with $HOBr/OBr^-$ was dominant. The differential equations based on the stoichiometry of bromate formation were established to predict the formation rate of bromate by ozonation. The results shows good correlation with experimental results.

• 한국항공운항학회지
• /
• 제29권3호
• /
• pp.44-51
• /
• 2021

PIP is an abbreviation of 'Performance Improvement Package', which is a package that can improve performance by applying some design changes to existing aircraft. Boeing provides PIP applicable to B777-200, and Airbus provides PIP applicable to A350-900 as standard. PIP provided by Boeing and Airbus is a separate task, but it is expected to reduce fuel consumption by reducing drag through aerodynamic improvements. The PIP applied to the A350-900 includes work such as increasing Winglet Height and re-twisting Outboard Wing. This study is to verify the effect of PIP application of the A350-900 aircraft and use it as basic data for economic analysis. The aerodynamic improvement studies and expected effects of the PIP application were examined, and the actual flight data of the PIP-applied and the non-applied aircraft were compared to confirm the PIP application effect. This paper provides empirical results for the aviation industry on the PIP application efficiency as a method of improving fuel efficiency and reducing carbon emission.

• 한국항공운항학회지
• /
• 제29권2호
• /
• pp.14-24
• /
• 2021

This study aims to examine probable human errors when landing an airplane by the use of SHERPA(systematic human error reduction and prediction approach) and propose methods for preventing the predictive human errors. It has been reported that human errors are concerned with a lot of accidents or incidents of an airplane. It is significant to predict presumable human errors, particularly in the operation mode of human-automation interaction, and attempt to reduce the likelihood of predicted human error. By referring to task procedures and interviewing domain experts, we analyzed airplane landing task by using HTA(hierarchical task analysis) method. In total, 6 sub-tasks and 19 operations were identified from the task analysis. SHERPA method was used for predicting probable human error types for each task. As a result, we identified 31 human errors and predicted their occurrence probability and criticality. Based on them, we suggested a set of methods for minimizing the probability of the predicted human errors. From this study, it can be said that SHERPA can be effectively used for predicting probable human error types in the context of human-automation interaction needed for navigating an airplane.

• 한국항공운항학회지
• /
• 제30권2호
• /
• pp.34-43
• /
• 2022

In Efforts to prevent CFIT accidents so far, have been emphasizing various education measures to minimize the occurrence of human errors, as well as enforcement measures. However, current engineering measures remain in a system (TAWS) that gives warnings before colliding with ground or obstacles, and even actual automatic avoidance maneuvers are not implemented, which has limitations that cannot prevent accidents caused by human error. Currently, various attempts are being made to apply machine learning-based artificial intelligence agent technologies to the aviation safety field. In this paper, we propose a deep reinforcement learning-based artificial intelligence agent that can recognize CFIT situations and control aircraft to avoid them in the simulation environment. It also describes the composition of the learning environment, process, and results, and finally the experimental results using the learned agent. In the future, if the results of this study are expanded to learn the horizontal and vertical terrain radar detection information and camera image information of radar in addition to the terrain database, it is expected that it will become an agent capable of performing more robust CFIT autonomous avoidance.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2020년도 춘계학술발표대회
• /
• pp.91-94
• /
• 2020

본 연구에서는 4차 산업혁명의 핵심 분야인 가상현실을 헬스 엔터테인먼트 서비스에 응용하는 시스템을 개발하였다. 스마트폰에 내장된 GPS와 GYRO센서를 활용하여 로잉머신의 동작 상태를 이중 데이터로 측정하고, 분석한 값을 활용해서 Unity를 사용하여 AR 어플리케이션을 설계, 구현하였다. 어플리케이션을 AR 글라스를 통해 실행한 결과, 생동감 넘치는 운동 환경을 사용자에게 제공한다. 그러나 사용자의 시각적 부담 과다로 인하여 로잉머신 운동효과 경험에 부분적 장애를 유발할 수 있어 2차적 개선으로 VR 콘텐츠로 전환을 적용하여 안전한 운동효과를 검증하였다. 본 연구의 VR 콘텐츠 개선기술을 적용하면 사용자 안전에 우선하는 헬스 엔터테인먼트 시장의 활성화가 기대된다.