• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1505-1515
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• 2009

A new method to semicontinuously determine $PM_{2.5}$ ionic species with a short time resolution is described in detail. In this system, a particle collection section (mixing part, particle collection chamber, and air/liquid separator) was developed. A Y-type connector was used to mix steam and an air sample. The particle collection chamber was constructed in the form of a helix coil and was cooled by a water circulation system. Particle size growth occurred due to the high relative humidity and water absorbed particles were efficiently collected in it. Liquid samples were drained out with a short residence time (0.08-0.1 s). The air/liquid separator was also newly designed to operate efficiently when the flow rate of the air sample was 16.7 L $min^{-1}$. For better performance, the system was optimized for particle collection efficiency with various types of test aerosols such as ($NH_4)_2SO_4,\;NaCl,\;NH_4HSO_4,\;and\;NH_4NO_3$. The particle collection efficiencies were almost 100% at different concentration levels in the range over 500 nm in diameter but 50-90% in the range of 50-500 nm under the following experimental conditions: 15 coil turns, a water flow rate for steam generation of 0.65 mL $min^{-1}$, and an air sample flow rate of 16.7 L $min^{-1}$. Finally, for atmospheric applications, chemical compositions of $PM_{2.5}$ were determined with a time resolution of 20 min on January 11-24, 2006 in Seoul, Korea, and the chemical characteristics of $PM_{2.5}$ ions were investigated.

• 정보보호학회논문지
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• 제28권4호
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• pp.859-868
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• 2018

데이터베이스의 삭제된 데이터 복구와 관련된 그간의 연구는 삭제된 레코드가 트랜잭션 로그에 존재하는 경우이거나 데이터베이스 원본을 물리적 방식으로 수집하여 삭제 데이터의 탐지와 복구를 진행하는 방식이 주를 이루었다. 그러나 트랜잭션 로그가 존재하지 않거나 증거수집 현장에서 물리적 방식의 원본수집이 불가능한 경우 즉, 데이터베이스 서버 정지로 인해 피압수인이 업무상 손실 또는 권리침해를 이유로 거부하는 경우에는 적용하기 곤란한 한계가 있었다. 그러므로 증거수집 현장의 제약을 대비하기 위해 다양한 수집 방식을 살펴보고 이에 따른 삭제된 레코드의 복구 가능성에 대해서 확인해볼 필요가 있다. 이 논문에서는 Microsoft SQL Server 데이터베이스를 대상으로 하는 디지털포렌식 조사 시 원본 수집의 논리적 물리적 방식별로 수집된 원본 파일 내 삭제된 데이터의 잔존 여부를 실험하여 각 수집 방식에 따른 데이터 복구 가능성을 확인하였다.

• 한국정보전자통신기술학회논문지
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• 제14권4호
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• pp.300-306
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• 2021

IT기술의 발달로 인해 최근 IoT 장비에 적용되는 하드웨어 기술이 저비용, 고성능 RF 및 연산장치를 사용한 스마트 시스템들로 변화되고 있다. 그러나 방대한 양의 IoT 장비들이 설치된 인프라 환경에서 빅데이터 수집은 전송되는 데이터간 병목현상으로 인해 수집 서버의 부하가 발생한다. 이로인해 데이터수집 서버로 전송되는 데이터는 패킷 손실 및 데이터 처리율 감소 현상이 발생한다. 따라서 방대한 양의 IoT 장비들이 설치된 인프라 환경에서 효율적인 빅데이터 수집 기법이 필요하다. 이에 본 논문에서는 방대한 양의 IoT 장비들이 설치된 인프라 환경에서 효율적인 빅데이터 수집 기법을 제안한다. 성능평가 결과, 제안하는 기법의 패킷 손실 및 데이터 처리율은 전송되는 파일의 손실없이 전송이 완료된다. 향후 본 설계를 기반으로 시스템이 구현이 필요하다.

• 창의정보문화연구
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• 제7권4호
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• pp.265-277
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• 2021

인공지능 기술의 핵심은 데이터다. 기술의 발달로 데이터의 양이 이전보다 폭발적으로 증가하면서 인공지능 기술 또한 빠르게 발전하고 있다. 하지만 인공지능 교육에 대한 높은 관심에 비해 인공지능과 연계된 데이터 교육 연구는 아직 부족하다. 기존의 인공지능 데이터 교육의 사례 분석 결과, 데이터 과학의 과정 및 일부를 교육하는 사례를 확인할 수 있었으나, 데이터 수집과 관련된 연구는 많지 않았다. 피지컬 컴퓨팅 교구의 활용이 초등학생의 인공지능 교육에 긍정적인 영향을 줄 것이라는 연구와 함께 피지컬 도구를 활용한 데이터 수집 사례를 연구하였으나, 데이터 수집과 관련한 연구 사례 또한 드물었다. 따라서 본 연구에서는 피지컬 도구를 활용한 효율적인 데이터 수집 방법을 설계하였다. 모듈형 피지컬 컴퓨팅 교구인 코블S를 활용하여 데이터 수집 프로그램의 구조도를 만들고 서비스 측면과 사용자 측면의 프로그램 화면의 예시를 구성하였다. 본 연구는 설계 측면의 제안으로 향후 프로그램 제작 및 프로그램과 연동하여 사용할 수 있는 인공지능 교육 플랫폼 구축이 되어야 한다는 점에서 제한점이 있다.

• International Journal of Contents
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• 제6권4호
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• pp.22-29
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• 2010

In flash memory, many previous garbage collection methods only merge blocks statically and do not consider the contents of buffer. These schemes may cause more unnecessary block erase operations and page copy operations. However, since flash memory has the limitation of maximum rate and life cycle to delete each block, an efficient garbage collection method to evenly wear out the flash memory region is needed. This paper proposes a memory compaction scheme based on block-level buffer for flash memory. The proposed scheme not only merges the data blocks and the corresponding log block, but also searches for the block-level buffer to find the corresponding buffer blocks. Consequently, unnecessary potential page copying operations and block erasure operations could be reduced, thereby improving the performance of flash memory and prolonging the lifetime of flash memory.

• Journal of Nutrition and Health
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• 제20권2호
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• pp.83-89
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• 1987

This study was conducted to investigate the effect of repeated blood collection on the amount of vitamin E in serum and liver of the rats fed standard diet. Rats (Sprague Dawley strain) were fed standard were fed standard diet for several weeks. Blood was collected with on improved cardiac puncture method at regular intervals . The amount of vitamin E analogs were measured by the HPLC. 1) The growth curve of all groups was normal, but bodyweight gains of group II were significantly decreased in case of 7 week- rats whose blood was collected at intervals of two weeks. 2) The amount of vitamin E analogs in serum of rats during growth increased, but continuos blood collection could not affect on the amount of vitamin E in serum. Especially, in the group I serum vitamin E equivalent were significantly higher in case of 7 weeks than first week. 3) The amount of liver vitamin E analogs were changed irregularly, and especially, $\alpha$-Tocopherol equivalent were significantly higher in group II then other groups.

• 한국대기환경학회지
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• 제17권3호
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• pp.259-268
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• 2001

In this study, we have developed a simulation method to predict the initial collection efficiency of a unipolar charged fiber in the electret filters. The particle sizes considered were in the submicron range and thus Brownian motion of particles was also taken into consideration along with electrostatic forces acting on the particles. The simulation results were compared with other investigators experimental data on single fiber efficiency as well as with the calculated results using the existing correlations on single fiber efficiency. It has been shown that simulation results are in good agreement both with the experimental data with those predicted by the correlations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1236-1238
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• 2001

The electrified railway has various power supply schemes. Although the identical trains are operated in same condition and the impedance of track are equal, the genealogy impedance of track is changed according to composition method of feeding scheme. So, the collection voltage of train and supplying power from railway substation are greatly unlike. For simulation of collection voltage and power supply according to feeding scheme, using 6-port network analysis proposed previously simulate collection voltage and supply power according to feeding scheme(Parallel Post feeding system, normal feeding system and tie feeding system) and compare and investigate each characteristics.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2004년도 춘계학술대회
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• pp.211-224
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• 2004

Distributing information on the internet is common in our daily life. In the past, e-mail has been the primary choice of exchanging information, but instant messengers are gaining popularity abroad and domestically because of their immediate responses. Instant messaging has become the fastest growing communication technology in recent years. Instant messaging is effectively a chat room for two people. Users that have accounts with the same provider are able to send messages via computer in real time. Instant messaging has exploded into the business world as companies now utilize the technology for everything from interoffice communication to client/customer communication. In this paper, we propose a method of instant messenger system design for effective collaboration of statistical data collection.

• International Journal of Oral Biology
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• 제44권3호
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• pp.101-107
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• 2019

The purpose of this study was to investigate the antimicrobial activity of the ethanol extract of Garcinia mangostana L. (mangosteen) against Cutibacterium acnes (6 strains) and Staphylococcus aureus (6 strains). The antimicrobial activity of the mangosteen extract was evaluated based on its minimal bactericidal concentration. Cytotoxicity of the mangosteen extract against human embryonic kidney 293 (HEK 293) cells was determined using the cell counting method. The data showed that the mangosteen extract was not toxic to HEK 293 cells at a concentration of up to $16{\mu}g/mL$ and killed 87.0% and 99.9% of C. acnes and S. aureus after 10 minutes and 1 hour of treatment, respectively. These results suggest that ethanol extract of mangosteen can be used as an anti-acne agent.