• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1799-1810
• /
• 2011

Origin-Destination(OD) trip survey being used in travel demand forecasting has been obtained through totalizing process with direct sample survey techniques such as plate license survey, roadside interview, household travel survey, and cordon line counts. However, the OD survey has many discrepancies in sampling, totalizing process, and such discrepancies contains problems of difference between forecasted traffic volume and observed data. On the other hand, transit smart card data recently collected has credible resource of obtaining travel information for bus and metro. This paper presents parameter estimation of gravity model by using transit smart card data. Through the parameter estimation method, we estimated =0.57, ${\beta}$=0.14 of gravity model for bus, and ${\alpha}$=-0.21, ${\beta}$=0.05 for metro. The statistical test such as T-test, coefficient of correlation, Theil`s inequality coefficient showed no difference between observed volume and estimated volume. Elasticities of bus and metro derived in this paper are also reasonable.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.373-375
• /
• 2002

4D CT is a dynamic volume imaging system of moving organs with an image quality comparable to conventional CT, and is realized with continuous and high-speed cone-beam CT. In order to realize 4D CT, we have developed a novel 2D detector on the basis of the present CT technology, and mounted it on the gantry frame of the state-of-the-art CT-scanner. In the present report we describe the design of the first model of 4D CT-scanner as well as the early results of performance test. The x-ray detector for the 4D CT-scanner is a discrete pixel detector in which pixel data are measured by an independent detector element. The numbers of elements are 912 (channels) ${\times}$ 256 (segments) and the element size is approximately 1mm ${\times}$ 1mm. Data sampling rate is 900views(frames)/sec, and dynamic range of A/D converter is 16bits. The rotation speed of the gantry is l.0sec/rotation. Data transfer system between rotating and stationary parts in the gantry consists of laser diode and photodiode pairs, and achieves net transfer speed of 5Gbps. Volume data of 512${\times}$512${\times}$256 voxels are reconstructed with FDK algorithm by parallel use of 128 microprocessors. Normal volunteers and several phantoms were scanned with the scanner to demonstrate high image quality.

• Asian Journal of Atmospheric Environment
• /
• v.12 no.1
• /
• pp.78-86
• /
• 2018

Filter-based sampling techniques are the conventional way to collect particulate matter, but particles collected and entangled in the filter fibers are difficult to be removed and thus not suited for the following cell- and animal-based exposure experiments. Collecting aerosol particles in powder form using a cyclone instead of a filter would be a possible way to solve this problem. We developed a hybrid virtual-impactor/cyclone high-volume fine and coarse particle sampler and assessed its performance. The developed system achieved 50% collection efficiency with components having the following aerodynamic cut-off diameters: virtual impactor, $2.4{\mu}m$; fine-particle cyclone, $0.18-0.30{\mu}m$; and coarse-particle cyclone, $0.7{\mu}m$. The virtual impactor used in our set-up had good $PM_{2.5}$ separation performance, comparable to that reported for a conventional real impactor. The newly developed sampler can collect fine and coarse particles simultaneously, in combination with exposure testing with collected fine- and coarse-particulate matter samples, should help researchers to elucidate the mechanism by which airborne particles result in adverse health effect in detail.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.562-571
• /
• 2003

A series of factors such as sampling, pretreatment measurement, volume estimation which induces uncertainty of the calculated radioactivity in liquid effluent released from a nuclear power plant were analyzed. It is innately impossible to estimate exact error of the calculated radioactivity, since most of the input parameters are determined by a single measurement and true value of the released radioactivity cannot be known. In this paper, a systematic model to calculate uncertainty of the released liquid radioactivity was developed based upon the guidance report published by the ISO in 1993, and the model was applied to a set of hypothetical batch release conditions. As a result, the Priority of each input parameter was turned out to be (1) wastewater volume, (2) sample volume, and (3) measured radioactivity of the sample. In addition, probability distribution of the released radioactivity was simulated by Monte Carlo method combining the probability distribution of each input parameter It was shown that the radioactivity released to the environment, which has been reported as a single value, has a certain form of probability distribution.

• Asian Journal of Atmospheric Environment
• /
• v.7 no.2
• /
• pp.65-71
• /
• 2013

Japanese cedar (Cryptomeria japonica) pollinosis is the most popular pollinosis in Japan. It has been reported that Cryptomeria japonica pollen allergenic species are suspended as fine particles in the urban atmosphere. These allergenic fine particles are responsible for inducing asthma by breaking into the lower respiratory tract. It has also been found that pollinosis symptoms on the sufferers appear mainly at night-time by the results from epidemiological studies. However, the exact reason for these phenomena is not yet clarified. In this study, the diurnal and nocturnal behaviours of Cryptomeria japonica pollen grains and their allergenic species in the urban area of Saitama city of Kanto Plain were investigated. Airborne pollen grains and allergenic Cry j 1 concentrations in total suspended particulate matter (TSP) were investigated at two sampling sites, a heavy traffic road (roadside site) and at the balcony of the $10^{th}$ floor of the Building of Research and Project of Saitama University (general urban site). The latter sampling site where located about 300 m away from the roadside site was used as a general urban site unaffected by automobile traffic. The airborne pollen counts were measured with a real-time pollen monitor. Cry j 1 particles were collected with two high volume air samplers, and these concentrations were measured by surface plasmon resonance method with a Biacore J system. The diurnal variation of the airborne pollen counts was similar to the trends of temperature and wind speed during the day-time; whereas its tendency with wind speed trend was not observed during the night-time. Airborne pollen counts were lower with northern wind than with southern wind because the pollen comes from the mountainous areas, and the mountains in the south are closer, about half the distance to the northern mountains. It is suggested that the peaks of airborne pollen counts during night-time in the sampling site occurred by transport of pollen grains released during day-time in the mountainous forest areas, located c.a. 100 km away from the sampling site. On the roadside site the allergenic Cry j 1 concentrations were higher than at the general urban site, nevertheless pollen grains counts were lower. These results suggested that worsening of pollinosis symptoms during night-time in urban area was caused by transport of pollen grains during day-time in the mountainous forest areas. Moreover, pollen allergenic species become different morphology from pollen grain at roadside site, and the subsequent pollen grains re-suspension by automobile traffic.

• Journal of Korean Society for Atmospheric Environment
• /
• v.30 no.6
• /
• pp.586-599
• /
• 2014

During the last two decades, indoor air quality and volatile organic compounds (VOCs) have been of concern in Korean society due to their nature of potential health impacts. In order to investigate the pollution levels of VOCss in indoor environments, establishment of a solid test method for monitoring the airborne VOCss is essential. In Korea, a method based on adsorbent sampling and GC analysis coupled with thermal desorption was proclaimed as the Korea Standard Method for Indoor Air Quality Test. This study was carried out to examine some inherent problems of the VOCs measurement method. The VOCs method does not describe in detail preparing the standard samples. The standard samples may be prepared by impregnation of either liquid standard solutions or a mixture of standard gases. In this study, we investigated the optimal temperature condition for transferring the liquid standards onto a standard adsorbent tube. As a result, keeping the impregnation temperature at $250^{\circ}C$ will be recommended in regard of the boiling points of multiple target analytes and the thermal stability of the adsorbent. We also demonstrated some problems associated with handling of a syringe used for transferring the standard solutions onto the adsorbent tubes, and a best way to get rid of the syringe problems was suggested. Finally, a number of field works were conducted to evaluate the performance of adsorbent sampling methods. Comparison of different adsorbent tubes, i.e. tube packed with single sorbent (Tenax) and double sorbents (Tenax with Carbotrap), revealed that 30 to 40% differences between the two groups, implying that sampling efficiency is depending on the volatility and the strength of adsorbents. However, duplicate precisions for VOCs sampling with a same type of adsorbent and at same flow rates appeared to be satisfactory to be all within 20%, which is a quality control guideline. Distributed volume precisions were also found to be within a guideline value, 25%, although the precision was in general inferior to the duplicate precision. The Korea indoor VOCs test method should be more refined and improved in many aspects, particularly procedure and instrumentation for preparing the standard samples and specification of quality control assessment.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.2
• /
• pp.131-141
• /
• 2004

For geotechnical applications, engineers use data obtained from a site investigation to interpret the structure and potential behavior of the subsurface. In most cases, these data consist of samples that represent 1/100,000 or less of the total volume of soil. These samples and associated field and lab testing provide the information used to estimate soil parameter values. The resulting values are estimated ones and there exists some likelihood that actual soil conditions are significantly different from the estimates. This may be the case even if the sampling and interpretation procedures are performed in accordance with standard practice. Although these efforts have been made to characterize the uncertainty associated with geotechnical parameters, there is no commonly accepted method to evaluate quantitatively the quality of an investigation plan as a whole or the relative significance of individual sampling points or potential sampling points.

• Journal of Biomedical Engineering Research
• /
• v.25 no.6
• /
• pp.557-563
• /
• 2004

A new vacuum assisted auto-lancing technique is proposed to minimize pain. Specially designed lancing device was introduced, which applied -100mmHg right after skin puncture on the forearm. Sampled blood volumes were measured in 58 normal females. Mean volume of 464 samples was approximately 2.6$\muL$ and the frequency of more than 0.5$\muL$ was 86%. Thus the success rate of blood sugar test should also be the same when using modern glucose meters capable of testing with only 0.3~0.5$\muL$ of capillary blood. When pain scores were quantitatively evaluated by the visual pain measure, only 23% pain of the traditional finger sampling was experienced, demonstrating that capillary blood sampling was performed on the forearm with almost no pain. The present technique reduced pain to a great degree, though resampling might be unavoidable due to 14% of test failure rate estimated for modern glucose meters. However, minimized pain makes the present technique of great convenience for diabetic patients who need blood sampling a few times a day.

• Journal of the korean Society of Automotive Engineers
• /
• v.7 no.2
• /
• pp.18-26
• /
• 1985

최근에 들어 환경보전에 대한 시민의식이 고조되고 깨끗한 자연 및 생활환경을 유지하려는 노력 이 각계에서 일고 있다. 이와 관련된 문제점의 하나가 대기오염이며 이 오염원 중의 하나가 자 동차 배기물로서 특히 탄화수소(hydrocarbon:HC), 일산화탄소(CO), 질소산화물(NO$_{x}$)에 의 한 대기오염의 심각히 대두되어 왔으며 현재 환경청 등에 의해 국가적 차원에서 자동차 배기물에 대한 규젤ㄹ 강화하려는 움직임을 보이고 있다. 미국의 경우 연도별 배기규제기준을 살펴 보면 표.1 과 같으며, 국내에서도 88년까지 미국, 일본수준으로 신규제작차의 배출혀용기준을 강화할 계획으로 있다. 표1의 규제치르 보면 60년대의 비규제기간중의 배출량에 비해 탄화수소의 경우 96%, CO는 96%, NO$_{x}$는 76%의 감소를 보여주고 있으며 이 규제치는 5만mile을 규정된 방법으로 주행한 후 복잡한 사이클과정의 연방정부 시험절차 (Federal Test Procedure, FTP 또는 Constant Volume Sampling-Cold and Hot, CVS-CH)를 거쳐 만족하여야 한다. 상기의 규제치들을 만족시키기 위한 실용적 방법으로서 촉매전환기(catalytic converter)가 채택되고 있 으며 따라 본 해설에서는 자동차용 촉매전화기에 대한 자료들을 정리하여 특성, 문제점 등을 살펴 보고자 한다.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2666-2671
• /
• 2007

This work presents microchannel heat sink shape optimization procedure using Kriging method. Design variables relating to microchannel width, depth and fin width are selected, and thermal resistance has been taken as objective function. Design points are selected through a three-level fractional factorial design of sampling method. Navier-Stokes and energy equations for laminar flow and conjugate heat transfer are solved at these design points using a finite volume solver. Solutions are carefully validated with experimental results. Using the numerically evaluated objective function, a surrogate model (Kriging) is constructed and optimum point is searched by sequential quadratic programming. The process of shape optimization greatly improves the thermal performance of microchannel heat sink under constant pumping power.