이민혁

이민혁 충북연구원 2009 앞,뒤 바라보다 Vol.- No.1

지역 속으로 : 자치단체 정보화사업 ; 민원인은 쉽게! 공무원은 편하게! -사회복지민원이지(easy)시스템

이민혁 한국지역정보개발원(구 자치정보화조합) 2016 지역정보화 Vol.96 No.-

왕우렁이를 이용한 식물플랑크톤 대발생 제어

이민혁,김민지,김용재 한국환경생물학회 2015 환경생물 : 환경생물학회지 Vol.33 No.1

This study is measured the change of chlorophyll-a concentration and phytoplanktondensity, the grazing rates (GR) and pseudofaeces production (PFP), by grazing of freshwaterapple snail, Pomacea canaliculata, to investigated that the snails are able to control of phytoplanktonbloom. The experiments are performed to evaluate the GR and PFP at different conditionssuch as incubation time (0, 2, 4, 6, 8, 10 and 12 hr), shell height (1.0 to 4.0 cm, n=108), snaildensity (1, 1.5, 2.5, 3.5 and 5 indiv. L-1) and food concentration (200, 400, 600, 800 and 1000 μg L-1). Regarding feeding time, the highest GR (2.5 L. gAFDW-1 h-1) and PFP (15.3 mg AFDW-1) showedat 4 hr after snail stocking, respectively. The snail, smaller than 1.5 cm in body size, showed thehighest of GRs (2.54 L. gAFDW-1 h-1) for the initial period (2 hr of stocking), compared to thosegreater than 1.5 cm, which showed a stable FR, higher than 0.099 L. gAFDW-1 h-1. Upon snaildensity effect, the density of 5 indiv. L-1 induced the most effective inhibition on phytoplanktonbiomass with the highest PFP. On the food concentration, the highest GR (0.54 L. gAFDW-1 h-1)and PFP (8.5 mg gAFDW-1) were induced at the level of 600 μg L-1, respectively. We checked thatit is possible to control of phytoplankton bloom by the grazing of apple snail as well as Reeve. However, it required a through research for the remove of pseudofaeces and 2nd problem by thedecomposition of the organic materals.

MIMO-PFDM 시스템에서 적응비트로딩 알고리즘의 성능평가

이민혁,변건석 동아대학교 정보기술연구소 2006 情報技術硏究所論文誌 Vol.14 No.1

Combined with multiple antennas at the transmitter and the receiver as well as adaptive modulation, OFDM proved to be robust against channel delay spread, in this paper. Futhermore, the optimal adaptive bitloading algorithm is proposed and the analysis was considered to involve the application of a variable-bit allocation and variable-power MQAM technique for a Single-Input Single-Output (SISO) OFDM system. This is compared with the performance of fixed OFDM transmission where a constant rate is applied to each subcarrier. The applied adaptive bitloading algorithm was in use as an inherent assumption in subchannel gain. Given this knowledge, the proposed system was designed to allocate the bit and power according to each subchannel. To prove the performance of adaptive bitloading algorithm, the simulation of SISO-OFDM system was conducted. It was concluded that the decision of bit numbers and power optimization algorithm served well to improve performance. Also, adaptive modulation was applied to a general MIMO system by making use of the singular value decomposition(SVD) to separate the MIMO channel into parallel subchannels. We can decompose the MIMO channel on each tone into parallel non-interfering SISO channels using the SVD. Namely, every matrix channel can be decomposed into a set of parallel subchannels over which data can be transmitted independently, given appropriate precoding and shaping transformations at the transmitter and the receiver, respectively. Finally, adaptive modulation combined with MIMO-OFDM system using an adaptive bitloading algorithm was applied to improve system performance. For a two-input antenna, two-output antenna system, the performance is compared with the performance of a system with a four-input antenna and a four-output antenna. Through MIMO-OFDM system simulation, we found that using more transmitter antenna and receiver antenna progress system performance because of increment of channel capacity, finally. Further, we concluded that the MIMO-OFDM system appling bitloading algorithm in general leads to better BER performance, as well as outperforming a common MIMO-OFDM system. A very useful extension of this paper would be in MIMO-OFDM systems with channel estimation technique. Throughout it, the performance analysis of more practical system is expected from now on.

MIMO-OFDM 시스템에서 적응비트로딩 알고리즘의 성능평가

이민혁,변건식,Lee Min-Hyouck,Byon Kuk-Sik 한국정보통신학회 2006 한국정보통신학회논문지 Vol.10 No.4

고속데이터 전송이 요구되는 경우, OFDM(Orthogonal Frequency Division Multiplexing)은 다중경로에 의해 발생되는 주파수 선택성 페이딩에 쉽게 대처할 수 있다는 장점 때문에 다양한 고속 무선 통신 시스템에 채택되어왔다. 본 논문에서는 최적의 적응 비트로딩 알고리즘을 제안하고, 이를 확인하기 위해 SISO(Single Input Single Output)-OFDM 시스템에 이 알고리즘을 적용하고 고정 변조를 사용하는 SISO-OFDM과 비교 분석 하였다. 특히 다중 경로페이딩 채널에서 채널을 알고 있는 경우, MIMO(Multiple Input Multiple Output) 시스템의 적응 비트로딩을 시험하기 위해, 특이치 분해(SVD : Singular Value Decomposition)를 사용하여 MIMO 채널을 SISO 채널로 병렬 분해하여, 제안한 적응비트로딩 알고리즘을 적용하였다. 시뮬레이션 결과, 적응 비트로딩 MIMO-OFDM 시스템은 SISO-OFDM 시스템 보다 BER 성능이 우수함을 확인하였다. In the case of the requirement of high speed transmission, OFDM is a powerful technique employed in communications systems suffering from frequency selective fading. In this paper, we apply an optimal adaptive bitloading algorithm technique. The BER performance of the fixed-rate SISO and adaptive SISO is simulated. Specially, we can decompose the MIMO channel into the SISO channel by making use of the singular value decomposition(SVD) assuming channel knowledge in a multipath environment. As a results of simulation, we confirmed that the BER enhancement of MIMO-OFDM system with the bitloadins algorithm was superior to the SISO-OFDM system.

Invitation

이민혁,정상설 대한외과학회 2013 대한외과학회 학술대회 초록집 Vol.2013 No.11

대피경로 할당 알고리즘을 이용한 실내 대피시뮬레이션

이민혁,남현우,전철민 대한산업공학회 2016 대한산업공학회 춘계학술대회논문집 Vol.2016 No.4

재조합 CGTase를 이용한 vitamin C-Glucoside 유도체의 합성

이민혁,홍남규,이예진,진미정,김준수,유환구,김훈,이우일 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.1

Effect of economic crisis on entrepreneurship

이민혁,백철우,이정동 한국산업경제학회 2015 한국산업경제학회 정기학술발표대회 논문집 Vol.2015 No.12

자색 백향과(Passiflora edulis f. edulis) 과피 추출물의 항산화 효과및 세포 생리 활성에 미치는 영향

이민혁,강상모 대한미용학회 2018 대한미용학회지 Vol.14 No.4

Currently, the passion fruit (Passiflora edulis f. edulis) used in varying drinks tends to be cultivated more in Korea. The rind of passion fruit is thrown away, and its amount is on the rise. Interestingly, a use for passion fruit rind as a cosmetic product material was recently identified. The rind of passion fruit was extracted in 50% ethanol to measure anti-oxidative activity using DPPH radical elimination analysis, as well as FRAP and TEAC assays. The results of these test reveal high anti-oxidative activity of this extract. In addition, total polyphenol and flavonoid contents were measured. Large amounts of polyphenol and flavonoid influenced anti-oxidative activity. Regarding cell bioactivity, neutral red assay was conducted revealing no cytotoxicity associated with this extract. A degree of the generation suppression of ROS in cells, and anti-inflammatory, skin whitening, and anti-ageing effects were measured. Cell bioactivity was significantly effective at 10 μg/mL (considered a low concentration). Therefore, this study suggests that the extract of passion fruit rind can be used as a functional cosmetic product material. 본 연구를 통해 자색 백향과 과피 추출물이 피부개선을 위한 기능성 화장품의 소재로 활용이 가능성을 확인하고자 항산화활성 및 피부세포에서의 항염, 미백, 항노화 효과를 연구하였다. 실험결과 DPPH, FRAP, TEAC assay 모두 농도 의존적으로 항산화력이 증가하는 양상을 보였으며, 총 폴리페놀의 함량은 105.81 ± 2.85 mg/g이었고, 총 플라보노이드 함량은 15.94 ± 2.61 mg/g으로 나타났다. 세포 내 ROS 저해율에 있어서도 50 μg/mL 농도에서 훌륭한 항산화 효과를 확인하였다. 그리고 피부개선효과를 확인하기 위한 독성실험에서 RAW 264.7, B16F10, CCD-986sk의 모든 세포에서 자색 백향과 과피 추출물을 100 μg/mL 농도까지 처리했을 때 모두 85%이상의 세포 생존율을 확인하였다. RAW 264.7 세포를 이용한 항염 실험에서는 10 μg/mL의 저농도에서도 높은 수준의 NO생성 저해효과가 나타났으며, B16F10 세포를 이용한 미백 실험에서도 10 μg/mL의 저농도에서 멜라닌의 생합성을 효과적으로 억제하였다. CCD-986sk 세포를 이용한 항노화 효능 또한 10 μg/mL의 저농도의 추출물처리에도 MMP-1의 발현량을 현저히 낮췄다. 이와 같은 결과를 종합해 볼 때 자색 백향과 과피 추출물에 함유되어 있는 phenolic compounds의 높은 radical 소거 활성과 세포 내 ROS 생성 억제를 통한 항산화 효과를 나타낸 것으로 보인다. 또한 세포 독성이 낮고, 피부 개선 효과를 가진 화장품 소재로서의 개발 가능성이 있을 뿐만 아니라 주스로 가공하고 남은 자색 백향과의 과피 부분을 재활용하여 사용함으로서 경제적 효율성까지 있을 것으로 판단된다.