• 센서학회지
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• 제22권3호
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• pp.191-196
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• 2013

A particulate matter sensor fabricated by MEMS process is proposed. It is developed to accommodate Euro6 on-board diagnostics regulation for diesel automobile. In the regulation, emission of diesel particulate matter is restricted to 9 mg/km. Particulate matter sensor is designed to use induced charges by charged particulate matter. To increase sensitivity of the sensor, groove is formed on sensor surface because wider surface area generates more induced charges. Sensitivity of the sensor is measured 10.6 mV/(mg/km) and the sensor shows good linearity up to 15.7 mg/km. Also its minimum detectable range is about 0.25 mg/km. It is suitable to detect failure of a diesel particulate filter which should filter particulate matter more than 9 mg/km. For removing accumulated particulate matter on the sensor which can disturb normal operation, platinum heater is designed on the backside of the sensor. The developed sensor can sense very low amount of particulate matter from exhaust gas in real-time with good linearity.

• Journal of Astronomy and Space Sciences
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• 제35권2호
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• pp.83-92
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• 2018

The summer polar lower thermosphere (90-100 km) has an interesting connection to meteors, adjacent to the mesopause region attaining the lowest temperature in summer. Meteors supply condensation nuclei for charged ice particles causing polar mesospheric summer echoes (PMSE). We report the observation of meteor trail with nearly horizontal transit at high speed (20-50 km/s), and at last with re-enhanced echo power followed by diffusive echoes. Changes in phase difference between radar receivers aligned in meridional and zonal directions are used to determine variations in horizontal displacements and speeds with respect to time by taking advantage of radar interferometric analysis. The actual transit of echo target is observed along the straight pathway vertically and horizontally extended as much as a distance of at least 24 km and at most 29 km. The meteor trail initially has a signature similar to 'head echoes', with travel speeds from 20 - 50 km/s. It subsequently transforms into a different type of echo target including specular echo and then finally the power reenhanced. The reenhancement of echo power is followed by fume-like diffusive echoes, indicating sudden release of plasma as like explosive process probably involved. We discuss a possible role of meteor-triggered secondary plasma trail, such as fireball embedded with electrical discharge that continuously varies the power and transit speed.

• 지구물리
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• 제9권3호
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• pp.273-286
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• 2006

The Kyongsang Basin is the most representative Cretaceous basin in the Korean Peninsula where extensive crustal deformation and non-marine sedimentation took place in the early Cretaceous period. The lithology of the basement of the basin and adjacent areas is comprised of mainly Precambrian gneiss complex and Mesozoic granite intrusions. We have carried out magnetotelluric (MT) surveys to investigate the deep geoelectric structure around the Kyongsang Basin. The MT data were collected in the frequency range from 0.00042 to 320 Hz at 24 sites along a profile across the northern part of Kyongsang Basin. The results of MT inversion show that the thickness of sediments is estimated about 3 km to 9 km and the depth to base of granite intrusion is about 20 km. A remarkable discovery in this study is the highly conductive layer beneath the basin, having the resistivity of 1 ohm-m to 30 ohm-m and the thickness of about 3 km to 4 km or more. Although we are not able to reveal the nature of this layer, the result of this study could provide some basic information with respect to the formation process and deposit environment of the proto-Kyongsang Basin.

• 한국측량학회지
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• 제18권2호
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• pp.111-120
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• 2000

상수, 하수, 전기 그리고 가스 등의 시설물들은 우리 생활에 필요한 도시기반시설로서 대부분 지하에 매설되어 있어 지상시설물에 비해 효율적인 관리가 어렵다. 지하시설물 관리소홀로 발생하는 도시재난을 방지하고 도로굴착 중복공사에 따른 예산낭비와 교통체증을 감소시키기 위해서는 지하시설물에 대한 조사 탐사 및 데이터베이스 구축과 함께 지하시설물 데이터를 효율적으로 관리하기 위한 응용시스템 개발이 요구된다. 전주시는 국가지리정보체계 사업의 일환으로 1998년 12월부터 상수도 지하시설물 전산화 사업을 실시하여 시가화 구역 39.6$km^2$내 80 mm 이상의 상수관 물량 402.89 km 대한 조사/탐사 작업을 수행하였다. 또한 80mm 이하 537 km관에 대해서는 별도의 조사/탐사작업을 수행하지 않고 급수카드를 기초로 데이터베이스를 구축하였다. 또한 기존의 각 부서별 업무프로세스를 GIS 시스템을 활용할 수 있는 체계로 수정하였고 업무프로세스를 기반으로 상수도 지하시설물 관리시스템을 개발하였다. 개발된 상수도 지하시설물 관리시스템은 기본도관리, 상수도검수, 관로관리 및 관로조회, 공사관리, 운영관리 그리고 도면관리등의 하위시스템으로 구성되어 있다. 본 연구에서는 지하시설물 조사/탐사 과정 및 방법 그리고 조사/탐사 과정중 발생한 문제점을 도출하고 개발한 상수도 지하시설물 관리시스템을 구성하고 있는 각각의 서브시스템들의 기능들을 제시하였다.

• 한국지진공학회논문집
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• 제26권5호
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• pp.191-202
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• 2022

Markov envelope as a theoretical solution of the parabolic wave equation with Markov approximation for the von Kármán type random medium is studied and approximated with the convolution of two probability density functions (pdf) of normal and gamma distributions considering the previous studies on the applications of Radiative Transfer Theory (RTT) and the analysis results of earthquake records. Through the approximation with gamma pdf, the constant shape parameter of 2 was determined regardless of the source distance r_o. This finding means that the scattering process has the property of an inhomogeneous single-scattering Poisson process, unlike the previous studies, which resulted in a homogeneous multiple-scattering Poisson process. Approximated Markov envelope can be treated as the normalized mean square (MS) envelope for ground acceleration because of the flat source Fourier spectrum. Based on such characteristics, the path duration is estimated from the approximated MS envelope and compared to the empirical formula derived by Boore and Thompson. The results clearly show that the path duration increases proportionately to r_o^1/2-r_o², and the peak value of the RMS envelope is attenuated by exp (-0.0033r_o), excluding the geometrical attenuation. The attenuation slope for r_o≤100 km is quite similar to that of effective attenuation for shallow crustal earthquakes, and it may be difficult to distinguish the contribution of intrinsic attenuation from effective attenuation. Slowly varying dispersive delay, also called the medium effect, represented by regular pdf, governs the path duration for the source distance shorter than 100 km. Moreover, the diffraction term, also called the distance effect because of scattering, fully controls the path duration beyond the source distance of 300 km and has a steep gradient compared to the medium effect. Source distance 100-300 km is a transition range of the path duration governing effect from random medium to distance. This means that the scattering may not be the prime cause of peak attenuation and envelope broadening for the source distance of less than 200 km. Furthermore, it is also shown that normal distribution is appropriate for the probability distribution of phase difference, as asserted in the previous studies.

• 천문학회보
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• 제38권2호
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• pp.90.2-90.2
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• 2013

Filament eruptions are one of the energetic phenomena on the solar surface with flares and coronal mass ejections (CMEs). We observed the whole process of filament eruption that occurred in AR 11305 in association with a C5.6 flare on 2011 September 29th using the Fast Imaging Solar Spectrograph (FISS) and the Solar Dynamics Observatory (SDO). The eruption consists of a slow phase with a transverse speed of ~10 km $s^{-1}$ in 16 minutes and a fast phase with a transverse speed of ~200 km $s^{-1}$ in 3 minutes. Near the beginning of slow phase eruption, preflare brightening occurred beneath the filament in $H{\alpha}$ and some EUV images. The preflare brightening region is associated with a blue-shifted $H{\alpha}$ feature with a speed of ~60 km $s^{-1}$. It appears that this is the outflow from magnetic reconnection which may have occurred at relatively low atmosphere. Our result support the notion that the preflare brightening is a process of magnetic reconnection playing an important role in triggering the filament eruption by deformative the magnetic field lines under the eruptive filament.

• 한국환경농학회지
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• 제19권2호
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• pp.177-182
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• 2000

토양 미생물을 이용한 고농도 축산폐수의 과부하 처리를 위한 공정개발 연구결과 유기물 제거율은 99%이었다. 상온 혐기조에서 $0.7kg\;BOD/m^3/d$ 이하에서 처리수의 BOD 농도는 150mg/L 이하를 이었다. 상온 혐기조를 운전한 실험에서 후속 폭기조의 물질 대사계수(km)는 $0.73hr^{-1}$, 세포증식계수(Y)는 0.433 g/VSS/g BODrm/d 였으며 중온으로 운전한 경우 후속 폭기조에서 각각 $1.45hr^{-1}$과 0.776 g VSS/g BODrm/d 로 반응계수 값이 두 배에 가깝게 개선되었다.

• 한국군사과학기술학회지
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• 제14권5호
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• pp.888-896
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• 2011

A white smoke hand grenade, KM8 is used to make smoke screen in order to provide visual field interceptions or signals. The grenade fails when its time to emit smoke is longer than the specified emission time so that the smoke concentration becomes lighter. This paper considered failure in smoke emission time, and evaluated its storage lifetime. The main objective of this paper is to modify the present specification limits of smoke emission time for the efficient process control in manufacturing, through analyzing effect of its specification change on the storage lifetime, based on the lifetime evaluation results. Accelerated degradation test was performed and then failure in smoke emission time was reproduced from the test. And estimated storage lifetimes from the accelerated test results was compared to evaluated lifetimes of grenades using the ASRP data. Past process testing results of the grenade in manufacturing were analyzed in this paper. Then, each storage lifetime for the specifications, ${\pm}3$ and ${\pm}5$ in seconds, extended from the current specification in manufacturing were estimated using the past testing results, and compared to one another.

• 한국분무공학회지
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• 제23권4호
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• pp.227-233
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• 2018

An automobile is composed of a combination of a lot of parts, and it is difficult to maintain the same performance from a new car until it's scrapped. Greenhouse gases included in automobile emissions are typically carbon dioxide and methane. It is expected that this greenhouse gas will change depending on the aging (cumulative mileage) of the automobile However, the greenhouse gas characteristics by cumulative mileage lack of actual data due to time and economic difficulties. Therefore, in this paper, we selected automobile with high sales by displacement in korea and carbon dioxide and methane were measured by using method of the related law. The cumulative mileage is as follows; within 160 km (Statutory mileage by 2010), 6500 km (current statutory mileage), 15000 km (approximately 1-year average mileage of Non-business passenger vehicle). As a result of the test, the emission of carbon dioxide and methane was the smallest at 6,500 km, and increased in order of 15000 km, within 160 km. Also, it was confirmed that the $CO_2$ emission change of a large displacement automobile is more smaller at each mileage. Although the greenhouse gas tends to increase as the mileage of the vehicle, it is thought that additional confirmation is required of since 15,000 km as well, because it can occur deviations due to taming process or mechanical friction of the automobile.

• 대한예방한의학회지
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• 제23권2호
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• pp.25-42
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• 2019

Objectives : The purpose of this study was to identify factors that affect the utilization of Korean medicine (KM) among children with cerebral palsy (CP) and explore a processing model of decision-making by their parents. Methods : We conducted an individual in-depth interview with 21 mothers of children with CP who were recruited during the observational study. A grounded theory of Strauss and Corbin was used for qualitative analysis. Thus, collected data were classified into open coding including 121 concepts, 27 sub-categories and 7 categories. Results : The central phenomenon of the process of using KM for children with CP is 'KM as an optional treatment not essential'. Therefore there are many obstacles to starting KM treatment and it is easily interrupted for various reasons, unlike general rehabilitation treatment. However, if the patient experiences the therapeutic effect, the parents want to continue KM treatment. They try to provide treatment as much as possible if they can afford it. The parents give priority to general rehabilitation treatment and value the information and experience provided by the caregivers in similar situation as well as expert opinions. Conclusions : To expand and generalize KM treatment for children with CP, efforts to change interventional conditions such as treatment effect, treatment cost, treatment compliance, and convenience of treatment based on the understanding of the strategy used by the parents in KM utilization.