• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.63-66
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• 2003

This study applied a hydrogeological field survey and isotope investigation to identify source locations and delineate pathways of groundwater contamination by nitrogen compounds. The infiltration and recharge processes were analyzed with groundwater-level fluctuation data and oxygen-hydrogen stable isotope data. The groundwater flow pattern was investigated through groundwater flow modeling and spatial and temporal variation of oxygen isotope data. Based on the flow analysis and nitrogen isotope data, source types of nitrate contamination in groundwater are identified. Groundwater recharge largely occurs in spring and summer due to precipitation or irrigation water in rice fields. Based on oxygen isotope data and cross-correlation between precipitation and groundwater level changes, groundwater recharge was found to be mainly caused by irrigation in spring and by precipitation at other times. The groundwater flow velocity calculated by a time series of spatial correlations, 231 m/yr, is in good accordance with the linear velocity estimated from hydrogeologic data. Nitrate contamination sources are natural and fertilized soils as non-point sources, and septic and animal wastes as point sources. Seasonal loading and spatial distribution of nitrate sources are estimated by using oxygen and nitrogen isotopic data.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.8-14
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• 2007

Water quality in Lake Rotorua, New Zealand, deteriorated since the 1960s because of excessive phytoplankton growths due principally to increasing nitrogen and phosphorus in the lake waters. Nutrient concentrations in eight of the nine major streams feeding Lake Rotorua have increased since 1965. The groundwater system has a key role in the hydrology of the Lake Rotorua catchment and the groundwater system is probably the control on the time delay between intensification of agricultural land use and response of surface water quality. All major, and many minor streams, in the catchment are fed by springs. Two lithological units are most important to groundwater flow in the Lake Rotorua catchment: Mamaku Ignimbrite, erupted in about 200,000 years ago and Huka Formation sediments which filled the caldera left by the Mamaku Ignimbrite eruption. Rainfall recharge to groundwater in the groundwater catchment of Lake Rotorua is estimated as approximately 17300 L/s. A calibrated steady-state groundwater flow model estimates that approximately 11100 L/s of this flow discharges into streams and then into the lake and the balance travels directly to Lake Rotorua as groundwater discharge through the lake bed. Land use has impacted on groundwater quality. Median Total Nitrogen (TN) values for shallow groundwater sites are highest for the dairy land use (5.965 mg/L). Median TN values are also relatively high for shallow sites with urban-road and cropping land uses (4.710 and 3.620 mg/L, respectively). Median TN values for all other uses are in the 1.4 to 1.5 mg/L range. Policy development for Lake Rotorua includes defining regional policies on water and land management and setting an action plan for Lake Rotorua restoration. Aims in the action plan include: definition of the current nutrient budget for Lake Rotorua, identification of nutrient reduction targets and identification of actions to achieve targets. Current actions to restore Lake Rotorua water quality include: treatment of Tikitere geothermal nitrogen inputs to Lake Rotorua, upgrade of Rotorua City sewage plant, new sewage reticulation and alum dosing in selected streams to remove phosphorus.

• 대한기계학회논문집A
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• 제41권1호
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• pp.63-68
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• 2017

이 논문에서는 열간 사상압연 공정에서 스트립 통판성의 안정성과 판 품질 향상을 위하여 새로운 선진율 학습모델 개발에 관한 연구를 수행한다. 먼저 기존의 선진율 해석모델에 대한 고찰을 통해 스트립 장력, 루퍼 각도 그리고 롤 주속이 선진율 학습에 크게 영향을 미치는 주요 압연 인자들임을 보인다. 두 번째로는 선진율 학습의 주요 압연 인자들을 이용하여 새로운 선진율 학습모델을 도출한 후, 보조변수 규명 알고리즘을 이용하여 이산시간계 학습모델을 규명한다. 끝으로 컴퓨터 시뮬레이션을 통해 이 논문에서 제안한 새로운 학습모델이 기존의 학습모델보다 유용함을 보인다.

• 한국정밀공학회지
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• 제17권1호
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• pp.83-92
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• 2000

Sound intensity method is well known as a visualization technique of sound field or sound propagation in noise control. Sound intensity or energy flux is a vector quantity which describes the amount and the direction of net flow of acoustic energy at a given position. Especially two dimensional sound intensity method is very useful in evaluating periodic characteristics and acoustic propagation mode of noise source. In this paper, we have studied the noise source Identification, acoustic sound field analysis, and characteristics of noise source of rotary compressor and scroll compressor for air conditioner using complex sound intensity method. Also we proposed a now method of time domain analysis which is used in evaluating of position of noise source in rotary and scroll compressor in this paper This paper presents the advantage, simplicity and economical efficiency of this method by analysing the characteristics of noise source with two dimensional complex sound intensity simultaneously.

• 한국가시화정보학회지
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• 제17권2호
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• pp.48-57
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• 2019

A straightforward strategy for particle image velocimetry (PIV) interrogation and post-processing has been proposed, aiming at reducing errors and clarifying vortex structures. The interrogation window size should be kept small to reduce bias error and improve spatial resolution. A spatial filter is then applied to the velocity field to reduce random error and clarify flow structure. The performance of three popular spatial filters were assessed: box filter, median filter, and local quadratic polynomial regression filter. In order to quantify random uncertainty, the image matching (IM) method is applied to an experimental dataset of homogeneous and isotropic turbulence (HIT) obtained by 2D-PIV. We statistically analyze the uncertainty propagation through the spatial filters, and verify the reduction in random uncertainty. Moreover, we illustrate that the spatial filters help clarify vortex structures using vortex identification criteria. As a result, PIV random uncertainty was reduced and the vortex structures became clearer by spatial filtering.

• 문화기술의 융합
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• 제7권4호
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• pp.635-640
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• 2021

본 논문에서는 촬영된 주차장 사진으로부터 빈 주차 공간을 자동 식별할 수 있는 주차 공간 자동 식별 시스템에 대해 설명한다. 이 시스템은 딥러닝 기법에 기반한 시스템으로, 다양한 주차장 사진들을 토대로 학습을 진행하여 식별 결과의 정확도가 높으며, 기존의 주차 관리 시스템에 적용할 수 있다. 한편, 본 시스템은 손쉬운 적용 테스트를 위해, 스마트폰용 애플리케이션으로도 개발되었다. 따라서 스마트폰 카메라를 통해 주차장 사진을 찍으면, 촬영된 이미지를 자동 인식하며 빈 주차 공간을 자동 식별할 수 있다.

• International Journal of Computer Science & Network Security
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• 제23권11호
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• pp.183-189
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• 2023

A stroke is a medical disease where a blood vessel in the brain ruptures, causes damage to the brain. If the flow of blood and different nutrients to the brain is intermittent, symptoms may occur. Stroke is other reason for loss of life and widespread disorder. The prevalence of stroke is high in growing countries, with ischemic stroke being the high usual category. Many of the forewarning signs of stroke can be recognized the seriousness of a stroke can be reduced. Most of the earlier stroke detections and prediction models uses image examination tools like CT (Computed Tomography) scan or MRI (Magnetic Resonance Imaging) which are costly and difficult to use for actual-time recognition. Machine learning (ML) is a part of artificial intelligence (AI) that makes software applications to gain the exact accuracy to predict the end results not having to be directly involved to get the work done. In recent times ML algorithms have gained lot of attention due to their accurate results in medical fields. Hence in this work, Stroke disease identification system by using Machine Learning algorithm is presented. The ML algorithm used in this work is Artificial Neural Network (ANN). The result analysis of presented ML algorithm is compared with different ML algorithms. The performance of the presented approach is compared to find the better algorithm for stroke identification.

• 한국산학기술학회논문지
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• 제11권9호
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• pp.3125-3134
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• 2010

한국에서 삼원촉매 내구성은 1988년에 5년/80,000 km 이지만 2002년 이후로 10년/120,000 km이 요구된다. 국내의 삼원촉매는 배출가스 정화효율이나 압력강하 등이 만족하지만 열적 내구성은 만족시키지 못하고 있다. 삼원촉매는 내부에서 높은 온도를 유지하지만 외부 표면에서는 낮은 온도를 유지한다. 본 연구는 열유동과 구조해석 및 다음과 같은 과정에 의해서 열적 내구성을 평가하였다. 열유동 매개변수 범위는 차량시험과 열유동 해석에 의해 결정하였다. 후면 촉매 온도에 대한 반응 표면은 열유동 매개변수에 대한 실험계획법을 이용해 구성되었다. 차량시험에서 후면 촉매 온도에 대한 열유동 매개변수는 만족도 함수에 의해 예측하였다. 삼원촉매의 온도분포는 예측된 열유동 매개변수에 대한 열유동 해석에 의해 평가하였다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.423-426
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• 2004

공공건설임대주택의 사업비는 국민주택기금, 임대료, 임대보증금, 공사비, 금융비용 등 다양한 수익과 비용이 복합적으로 나타나게 된다. 따라서 공공건설임대주택 사업은 그 특성상 유동성과 재무탄력성에 대한 유용한 정보를 제공해 줄 수 있는 현금흐름예측이 필요하다. 그러나 현금흐름분석은 일부 시행하고 있었으나, 이를 예측 $\cdot$ 관리하고 있는 곳은 전무한 것으로 나타났다. 현금흐름 예측을 위한 일반적인 사항들은 실적자료와 문헌을 통하여 알 수 있으나, 현금흐름 예측의 정확성을 높이기 위한 리스크에 대한 연구는 전무한 실정이었다. 기존의 리스크에 대한 연구는 사업 전체에 대한 연구로 현금흐름과 정확한 상관관계를 알 수 없었다. 따라서 본 연구에서는 수익성 측면에서의 사업성분석 방법으로 현금흐름 예측방법을 제안하고 공공건설임대주택사업의 정확한 현금흐름예측과 관리를 위하여 현금흐름 각 항목에 영향을 미치는 리스크 인자들을 식별 $\cdot$ 분석 하고 그 대응방안을 모색하고자 한다.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.613-624
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• 2013

Multi-dimensional two-phase phenomena occur in many industrial applications, particularly in a nuclear reactor during steady operation or a transient period. Appropriate modeling of complicated behavior induced by a multi-dimensional flow is important for the reactor safety analysis results. SPACE, a safety analysis code for thermal hydraulic systems which is currently being developed, was designed to have the capacity of multi-dimensional two-phase thermo-dynamic phenomena induced in the various phases of a nuclear system. To validate the performance of SPACE, a two-dimensional two-phase flow test was performed with slab geometry of the test section having a scale of $1.43m{\times}1.43m{\times}0.11m$. The test section has three inlet and three outlet nozzles on the bottom and top gap walls, respectively, and two outlet nozzles installed directly on the surface of the slab. Various kinds of two-dimensional air/water flows were simulated by selecting combinations of the inlet and outlet nozzles. In this study, two-dimensional two-phase void fraction profiles were quantified by measuring the local gap impedance at 225 points. The flow conditions cover various flow regimes by controlling the flow rate at the inlet boundary. For each selected inlet and outlet nozzle combination, the water flow rate ranged from 2 to 20 kg/s, and the air flow rate ranged from 2.0 to 20 g/s, which corresponds to 0.4 to 4 m/s and 0.2 to 2.3 m/s of the superficial liquid and gas velocities based on the inlet port area, respectively.