• Asian Journal of Atmospheric Environment
• /
• 제11권2호
• /
• pp.107-113
• /
• 2017

This study describes (1) the impact of positive sampling artifacts caused by not only a filter-based sampling, but also a denuder-based sampling in the determination of particle-phase organic carbon (POC), (2) the effect of sample flow rate on positive artifacts, and (3) an optimum flow rate that provides a minimized negative sampling artifact for the denuder-based sampling method. To achieve the goals of this study, four different sampling media combinations were employed: (1) Quartz filter-alone (Q-alone), (2) quartz filter behind quartz-fiber filter (QBQ), (3) quartz filter and quartz filter behind Teflon filter (Q-QBT), and (4) quartz filter behind carbon-based denuder (Denuder-Q). The measurement of ambient POC was carried out in an urban area. In addition, to determine gas-phase OC (GOC) removal efficiency of the denuder, a Teflon filter and a quartz filter were deployed upstream and downstream of the denuder, respectively with varying sample flow rates: 5, 10, 20, and 30 LPM. It was found that Q-alone sampling configuration showed a higher POC than QBQ, Q-QBT, and Denuder-Q by 12%, 28%, and 23%, respectively at a sample flow rate of 20 LPM due to no correction for positive artifact caused by adsorption of GOC onto the filter. A lower quantity of GOC was collected from the backup quartz filter on QBQ than that from Q-QBT. This was because GOC was not in equilibrium with that adsorbed on the front quartz filter of QBQ during the sampling period. It is observed that the loss of particle number and mass across the denuder increases with decreasing sample flow rate. The contribution o f positive arti facts to POC decreased with increasing sample flow rate, showing 29%, 25%, and 22% for 10, 20, and 30 LPM, respectively. The 20 LPM turns out to be the optimum sample flow rate for both filter and denuder-based POC sampling.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제10권4호
• /
• pp.300-308
• /
• 2010

This paper describes the development of a low-power electrocardiogram (ECG) touch sensor intended for the use with two dry metal electrodes. An equivalent ECG extraction circuit model encountered in a ground-free two-electrode configuration is investigated for an optimal sensor read-out circuit design criteria. From the equivalent circuit model, (1) maximum sensor resolution is derived based on the electrode's background thermal noise, which originates from high electrode-skin contact impedance, together with the input referred noise of instrumentation amplifier (IA), (2) 60 Hz electrostatic coupling from mains and motion artifact are also considered to determine minimum requirement of common mode rejection ratio (CMRR) and input impedance of IA. A dedicated ECG read-out front end incorporating chopping scheme is introduced to provide an input referred circuit noise of 1.3 ${\mu}V_{rms}$ over 0.5 Hz ~ 200 Hz, CMRR of IA > 100 dB, sensor resolution of 7 bits, and dissipating only 36 ${\mu}W$. Together with 8 bits synchronous successive approximation register (SAR) ADC, the sensor IC chip is implemented in 0.18 ${\mu}m$ CMOS technology and integrated on a 5 cm $\times$ 8 cm PCB with two copper patterned electrodes. With the help of proposed touch sensor, ECG signal containing QRS complex and P, T waves are successfully extracted by simply touching the electrodes with two thumbs.

• 한국의학물리학회지:의학물리
• /
• 제31권4호
• /
• pp.189-193
• /
• 2020

An MR-based attenuation correction (MRAC) map plays an important role in quantitative positron emission tomography (PET) image evaluation in PET/magnetic resonance imaging (MRI) systems. However, the MRAC map is affected by the magnetic field inhomogeneity of MRIs. This study aims to evaluate the characteristics of MRAC maps of physical phantoms on PET/MRI images. Phantom measurements were performed using the Siemens Biograph mMR. The modular type physical phantoms that provide assembly versatility for phantom construction were scanned in a four-channel Body Matrix coil. The MRAC map was generated using the two-point Dixon-based segmentation method for whole-body imaging. The modular phantoms were scanned in compact and non-compact assembly configurations. In addition, the phantoms were scanned repeatedly to generate MRAC maps. The acquired MRAC maps show differently assigned values for void areas. An incorrect assignment of a void area was shown on a locally compact space between phantoms. The assigned MRAC values were distorted using a wide field-of-view (FOV). The MRAC values also differed after repeated scans. However, the erroneous MRAC values appeared outside of phantom, except for a large FOV. The MRAC map of the phantom was affected by phantom configuration and the number of scans. A quantitative study using a phantom in a PET/MRI system should be performed after evaluation of the MRAC map characteristics.

• 복식
• /
• 제67권1호
• /
• pp.56-73
• /
• 2017

The purpose of this study is to categorize the lotus patterns of traditional Korean fabrics. This study collected 169 fabrics of Korean lotus flower patterns and then made a list of era, configuration of pattern, type of artifact, findspot and holding institutions. It analyzes the characteristics of 251 kinds of lotus woven on 169 Korean fabrics, 251 kinds of lotus on 169 fabrics divided into Realistic Type, Design Type, and Abstract Type. They consist of 213 kinds of Design Type(84.8%), 21 kinds of Realistic Type(8.4%), and 17 kinds of Abstract Type(6.8%). The largest part of lotus patterns is Design Type. Design Types are subdivided into 14 types. This result contrasted with the conclusion of the research paper about peony patterns in Traditional Korean Textiles. The largest part of peony patterns was Realistic Types. Realistic Types of lotus patterns in Korean textiles are subdivided into 6 types. Korea has more diverse forms and a higher ratio of Realistic Types than China and this can be interpreted to reflect that there is a tendency in Korea to prefer natural patterns. Besides abstract Types are subdivided into 3 types. When the lotus flower patterns of Korea and China are categorized and similar types are compared, there are some unique patterns that appear only in Korea or China. Not only that, similar types display differences in pattern arrangement methods and portrayal among the two countries. If such study results are utilized, they can be grounds for distinguishing the production area of lotus flower textile fabrics when they are newly excavated in the future.

• 한국융합학회논문지
• /
• 제11권3호
• /
• pp.19-26
• /
• 2020

본 논문에서는 학습된 사전 기반 초해상도 결과를 개선하기 위해 분석한 손실 영역을 기반으로 학습 데이터를 적용하는 방법을 제안하였다. 기존의 학습된 사전 기반 방법은 입력 영상의 특징을 고려하지 않는 학습된 영상의 형태로 출력할 수 있으며, 이 과정에서 인공물이 발생할 수 있다. 제안하는 방법은 입력 영상과 학습된 영상의 일치하지 않는 특징으로 인한 인공물 발생을 줄이기 위해 1차 복원 결과를 분석함으로써 손실 정보를 추정하였다. 추정된 결과의 잡음 및 화소 불균형을 가우시안 기반의 커널로 개선하여 생성된 특징 맵에 따라 학습 데이터를 매핑하였다. 결과 비교를 위해 기존의 초해상도 방법과 제안 방법의 결과를 고화질 영상과 PSNR(Peak Signal to Noise Ratio), SSIM(Structural SIMilarity Index) 으로 비교한 결과 각각 4%와 3%의 향상된 결과를 확인하였다.

• 정보보호학회논문지
• /
• 제31권3호
• /
• pp.353-363
• /
• 2021

언택트(Untact) 시대로의 급속한 변화 속에서 협업 툴(Collaboration Tool)은 비대면 업무를 위한 디지털 솔루션으로써 그 활용도와 가치가 증대되고 있다. 협업 툴은 다양한 기능을 지원하는 한편, 그 편의성에 비례하여 정보 유출, 보안사고 등 디지털 범죄 및 사고우려 또한 내재되어 있어 디지털 포렌식 관점에서의 연구가 필요하다. 본 연구에서는 세계적으로 점유율이 가장 높은 협업 툴 Microsoft Teams에 대한 윈도우즈 및 안드로이드 포렌식 연구를 통해 주요 사용자 행위를 정의하고 각 행위들을 수행한 뒤 의미 있는 아티팩트가 존재하는지 확인하였다. 이후 각 운영환경에서 획득 가능한 아티팩트를 비교·분석하고 여기에서의 차이점을 바탕으로 한 차분 포렌식(differential forensic)을 통해 협업 툴 분석기법 및 수사 시나리오 등 활용 방안을 제시하였다.

• 지질공학
• /
• 제11권2호
• /
• pp.163-174
• /
• 2001

탄성파 굴절법 탐사를 이용한 지반조사시 탐사 결과로부터 표토층 및 풍화대 깊이, 연암 또는 기반암의 심도, 단층 파쇄대나 연약지반의 위치 및 규모, 지질경계 등을 파악, 지하 속도분포를 도출함으로서 Rippability 등 지반 공학적 특성의 정량적 평가가 가능하다. 이를 위하여는 양질의 자료 취득은 물론 조사 목적과 탐사심도에 맞는 측선길이 및 배치, 수진점과 진원점 감격 및 배치, 지형기복 여부 등 현장조사 파라미터의 설정이 중요하다. 택지개발 지역의 절토 사면부에서는 수진점 간격을 3∼5m 정도가 적합하며 측선의 배열은 주측선과 주요 지점에서 이에 사교하는 부측선 배치가 필요하다. 굴절법 토모그라피 해석기법의 적용시, 조사장비의 가용 채널 수에 1/4 이상의 진원점으로부터 자료를 취득해야 지하구조 해석시 지형의 영향에 의한 왜곡현상을 감소시킬 수 있다. 편마암 지대인 절토사면부에서 시추자료와 비교하여 탄성파 속도 토모그램에 의한 지반분류는 토사 700 m/s 이하, 풍화암 700∼1,200m/s, 연암 1,200∼1,800m/s 이고 굴삭난이도(리퍼빌리티)는 리핑암 700∼1,200m/s, 발파암 1,800m/s 이상으로 나타났다.