150 ㎒ 대역에서의 SAR 측정시스템의 유효성 연구

최동근(Donggeun Choi),김기회(Kihwea Kim),최재훈(Jaehoon Choi) 한국전자파학회 2013 한국전자파학회논문지 Vol.24 No.10

한국전파법에서 휴대전화에만 적용되었던 전자파흡수율(SAR: Specific Absorption Rate) 측정 대상기기가 2012년 1월 이후 인체로부터 20 ㎝ 이내에 위치하는 휴대용 송신 무선통신기기로 확대됨에 따라 150 ㎒ 대역의 무전기가 포함되어 이에 대한 SAR 적합성 평가를 위한 SAR 측정방법이 필요하다. 그러나 현재 SAR 측정방법에 대한 국제표준(IEC 62209-2)에서는 300 ㎒ 대역 이상의 주파수에 대해서 적용하고 있으며, 상용 SAR 측정시스템에서도 300 ㎒ 대역 이상의 주파수에 대해서만 측정이 가능하도록 되어 있는 실정이다. 본 논문에서는 150 ㎒ 대역의 SAR 측정 유효성 평가를 위한 기준 다이폴 안테나(복사체 길이: 760 ㎜, 반사 손실 : ?25.48 ㏈) 및 평면형 모의인체의 크기(1,300 ㎜(L)×900 ㎜m(W)×200 ㎜(H)), 수치해석 SAR 목표값(1 g: 1.08W/㎏, 10 g: 0.77 W/㎏)을 제시하였다. 제시된 기준 다이폴 안테나 및 평면형 모의인체를 제작하여 상용 SAR 측정시스템의 적합성 여부를 확인하였다. 측정된 1 g 및 10 g SAR 값은 각각 1.13 W/㎏, 0.81 W/㎏으로, IEC 국제 표준의 유효 범위인 ±10 % 이내를 만족하였다. 본 연구를 통해 도출된 규격들은 국내 SAR 측정방법 및 IEC 국제 표준으로 반영될 수 있을 것으로 기대된다. SAR measurement which was applied only to the mobile phone has been expanded in the Korean radio regulation law to the portable wireless communication equipments within 20 ㎝ from the human body since Jan. 2012. The two-way radio operating at 150 ㎒ frequency band was newly included following the revised radio regulation in the target equipment of measurement. SAR measurement system at 150 ㎒ satisfying this regulation is necessary accordingly for SAR conformity assessment. The international SAR measurement standard(IEC 62209-2) includes the evaluation method on frequencies above 300 ㎒, and the commercial SAR measurement system can measure SAR above 300 ㎒ only. The size of the reference dipole antenna(760 ㎜, return loss: ?27.57 ㏈) and flat phantom (1,300 ㎜(L)×900 ㎜(W)×200 ㎜(H)), targeted SAR values for numerical analysis(1 g: 1.08 W/㎏, 10 g: 0.77 W/㎏) for SAR validation evaluation at 150 ㎒ frequency are proposed in this paper. The suggested dipole antenna and flat phantom are assembled and used to verify the conformity assessment of commercial SAR measurement system. The measured SAR values of 1 g and 10 g were obtained respectively to be 1.13 W/㎏, 0.81 W/㎏, and they satisfied the effective range(within ±10 %) of IEC international standard. The standards based on this study are expected to be used for the domestic SAR measurement standard and IEC(International Electrotechnical Commission) international standard.

[특집/국제표준화기구] ITS 표준화 동향

최동근(Donggeun Choi) 한국자동차공학회 2002 오토저널 Vol.24 No.2

이중전극을 갖는 마이크로 팁 전극 어레이 제작

최동근(Donggeun Choi),박재형(Jae-Hyoung Park),이승기(Seung-Ki Lee) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.7

835 ㎒ 및 1,800 ㎒ 대역에서 인체의 전기적 특성을 가지는 한국인 손 모양의 팬텀 제작

최동근(Donggeun Choi),김윤명(Yoonmyoung Gimm),최재훈(Jaehoon Choi) 한국전자파학회 2013 한국전자파학회논문지 Vol.24 No.5

휴대전화의 이용이 증가하면서, 손에 미치는 전자파의 영향에 대한 관심이 증가하고 있다. IEC TC106에서도 휴대전화의 전자파 인체 노출량 평가 방법 표준에 손 영향을 반영하기 위하여 국제적인 교류 연구가 활발하게 진행되고 있다. 현재 상용화된 손 팬텀은 평균 서양인 손을 이용하고 있을 뿐만 아니라, 한 가지 형태의 파지(把持)만 가능하기 때문에, SAR 측정 결과에 대한 분석에 제한이 많은 실정이다. 손의 영향을 제대로 분석하기 위해서는 다양한 형태의 파지가 가능한 손 팬텀이 필요하다. 또한, 국내 환경에 맞는 손 팬텀의 개발이 필수적이다. 본 논문에서는 다양한 형태의 파지가 가능한 835 ㎒ 대역과 1,800 ㎒ 대역의 한국인의 젤리형 손 팬텀을 제작하였다. 제작된 손 팬텀의 전기적 특성은 비유전율과 도전율이 CTIA(미국이동통신산업협회) 권고 기준 값의 ±10 %이내로서, CTIA에서 제시하는 오차 기준(±20 %)보다 더 우수한 특성을 나타냈다. 또한, 손 팬텀의 3D CAD(3차원 컴퓨터 이용 설계) 파일을 개발하여 손에 의한 SAR 영향 분석을 위한 시뮬레이션에서 활용할 수 있도록 하였다. 본 연구를 통해 제작된 젤리형 손 팬텀과 3D 파일은 휴대 전화의 손 영향에 대한 연구에 유용하게 이용될 수 있을 것으로 본다. Interest of the hand effect on the electromagnetic wave are internationally increasing with the increase of the use of the mobile phone. IEC TC106(International Electrotechnical Commission, Technical Committee 106) promotes international research exchange program in order to reflect the effect of human hands in the standard assessment method of human exposure dosimetry by the electromagnetic wave of mobile phones. Since current commercialized hand phantom is manufactured by taking into account the average size of westerners and provides only one grip posture, it imposes many restrictions on the accurate SAR measurement. Therefore, the development of proper hand phantom accounting for domestic situation and various grip posture capability is essential in order to analyze the accurate effect of human hand on the exposure estimation. In this paper, a jelly hand phantom suitable for Korean was manufactured with various grip posture capability at 835 ㎒ and 1,800 ㎒ bands. Although the tolerances of permittivity and conductivity of the manufactured hand phantom are with ±10 % each, it was much less than CTIA(Cellular Telecommunication IndustryAssociation) tolerance of ±20 % at both bands. Its 3D CAD(3 Dimensional Computer Aided Design) file which was developed can be utilized for the simulation of human hand effect on SAR measurement of mobile phones. The findings in this study can be utilized for the analysis of human hand effect on SAR measurement of a mobile phone.

Molecular Biological Analysis for the Identification of Meloidogyne Species on Strawberry in Korea

Heonil Kang,Namsook Park,Donggeun Kim,Insoo Choi 한국응용곤충학회 2016 한국응용곤충학회 학술대회논문집 Vol.2016 No.04

This study is the identification of root-knot nematode (RKN), Meloidogyne hapla, from strawberry in Korea using molecular analyses. Strawberry plants showed localized stunting and galled roots. Molecular analyses of COⅡ/lrRNA, 28S rDNA D2-D3 segment and internal transcribed spacer (ITS) region were employed for the identification of Meloidogyne spp. Polymerase Chain Reaction (PCR) amplification of COⅡ/lrRNA region produced a single fragment ca 528bp. Restriction digestion of the amplified PCR products with Dra1 enzyme produced two fragments at 200 and 250bp indication M. hapla. 28S rDNA D2-D3 segment and ITS were cloned and sequenced. 28S rDNA D2-D3 segment and ITS region produced a single fragment of 1004bp and 560bp, respectively. In BLAST search in Genbank, all sequences accord with other known M. hapla. As a result, all of the RKN samples were M. hapla. This study suggests that the dominant species of RKN on strawberry is M. hapla in Korea.

Screening of Nematode Extraction Papers for Baermann Funnel Method

Heonil Kang,Jaehyun Lee,Insoo Choi,Donggeun Kim 한국응용곤충학회 2016 한국응용곤충학회 학술대회논문집 Vol.2016 No.04

The Baermann funnel method requires three to four Kimwipes tissues for clean nematode extraction. To find more efficient and economical nematode extraction paper, 14 different kinds of tissue papers were tested and compared with Kimwipes tissues. Nematode species used in the extraction efficiency test were juvenile (J2) of Heterodera spp., J2 of Meloidogyne spp., Pratylenchus spp., Rhabditis spp., Acrobeloides spp., Panagrolaimus spp., Poikilolaimus spp. and Diplogasterida. Extraction efficiency varied between 42.0 to 88.8%. Considering costs, extraction efficacy, and cleanness, one sheet of Pulling Kitchen Towel (MONALISA Co., Korea) is selected.

Resistance of Oil Seed Crops to Meloidogyne arenaria and M. incognita in Korea

Jihye Ha,Eulsoo Yun,Insoo Choi,Donggeun Kim 한국응용곤충학회 2016 한국응용곤충학회 학술대회논문집 Vol.2016 No.04

To select resistant oil seed crops against two species of root-knot nematodes, M. incognita and M. arenaria, 10 cultivars of sesame (Sesamum indicum) and 10 cultivars of perilla (Perilla frutescens var. japonica) were screened in greenhouse pot test. All sesame cultivars tested were resistant to M. incognita but susceptible to M. arenaria. While, perilla was resistant to both Meloidogyne species. Therefore, perilla cultivars could be used as rotation crops in greenhouses infested with both M. incognita and M. arenaria. But, sesame cultivars only can be used as a rotation crops in greenhouses infested with M. incognita but not for M. arenaria.

Fabrication and Characterization of Plasma-Polymerized Poly(ethylene glycol) Film with Superior Biocompatibility

Choi, Changrok,Hwang, Inseong,Cho, Young-Lai,Han, Sang Y.,Jo, Dong H.,Jung, Donggeun,Moon, Dae W.,Kim, Eun J.,Jeon, Chang S.,Kim, Jeong H.,Chung, Taek D.,Lee, Tae G. American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.3

<P>A newly fabricated plasma-polymerized poly(ethylene glycol) (PP-PEG) film shows extremely low toxicity, low fouling, good durability, and chemical similarity to typical PEG polymers, enabling live cell patterning as well as various bioapplications using bioincompatible materials. The PP-PEG film can be overlaid on any materials via the capacitively coupled plasma chemical vapor deposition (CCP-CVD) method using nontoxic PEG200 as a precursor. The biocompatibility of the PP-PEG-coated surface is confirmed by whole blood flow experiments where no thrombi and less serum protein adsorption are observed when compared with bare glass, polyethylene (PE), and polyethylene terephthalate (PET) surfaces. Furthermore, unlike bare PE films, less fibrosis and inflammation are observed when the PP-PEG-coated PE film is implanted into subcutaneous pockets of mice groin areas. The cell-repellent property of PP-PEG is also verified via patterning of mammalian cells, such as fibroblasts and hippocampal neurons. These results show that our PP-PEG film, generated by the CCP-CVD method, is a biocompatible material that can be considered for broad applications in biomedical and functional materials fields.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-3/am302208f/production/images/medium/am-2012-02208f_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am302208f'>ACS Electronic Supporting Info</A></P>

Identification of toxicological biomarkers of di(2-ethylhexyl) phthalate in proteins secreted by HepG2 cells using proteomic analysis

Choi, Seonyoung,Park, So-Young,Jeong, Ji,Cho, Eunkyung,Phark, Sohee,Lee, Min,Kwak, Dongsub,Lim, Ji-Youn,Jung, Woon-Won,Sul, Donggeun WILEY-VCH Verlag 2010 Proteomics Vol.10 No.9

<P>The effects of di(2-ethylhexyl) phthalate (DEHP) on proteins secreted by HepG2 cells were studied using a proteomic approach. HepG2 cells were exposed to various concentrations of DEHP (0, 2.5, 5, 10, 25, 50, 100, and 250 μM) for 24 or 48 h. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and comet assays were then conducted to determine the cytotoxicity and genotoxicity of DEHP, respectively. The MTT assay showed that 10 μM DEHP was the maximum concentration that did not cause cell death. In addition, the DNA damage in HepG2 cells exposed to DEHP was found to increase in a dose- and time-dependent fashion. Proteomic analysis using two different pI ranges (4–7 and 6–9) and large size 2-DE revealed the presence of 2776 protein spots. A total of 35 (19 up- and 16 down-regulated) proteins were identified as biomarkers of DEHP by ESI-MS/MS. Several differentiated protein groups were also found. Proteins involved in apoptosis, transportation, signaling, energy metabolism, and cell structure and motility were found to be up- or down-regulated. Among these, the identities of cystatin C, Rho GDP inhibitor, retinol binding protein 4, gelsolin, DEK protein, Raf kinase inhibitory protein, triose phosphate isomerase, cofilin-1, and haptoglobin-related protein were confirmed by Western blot assay. Therefore, these proteins could be used as potential biomarkers of DEHP and human disease associated with DEHP.</P>

Surface analysis of protein‐resistant, plasma‐polymerized ethylene glycol thin films

Choi, Changrok,Jung, Donggeun,Moon, Dae Won,Lee, Tae Geol John Wiley Sons, Ltd. 2011 Surface and interface analysis Vol.43 No.1

<P><B>Abstract</B></P><P>Poly(ethylene glycol) (PEG) has been widely used in biomedical applications because of its protein‐resistant and nontoxic properties. In this study, a plasma‐polymerized ethylene glycol (PPEG) thin film was deposited on a substrate using a capacitively coupled plasma chemical vapour deposition (CCP‐CVD) method with various plasma powers and ethylene glycol as a precursor. The surfaces of the PPEG thin films were characterized using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) along with a principal component analysis (PCA), and XPS. We confirmed that the PPEG thin film deposited at low plasma power closely resembles PEG polymers in terms of surface chemical composition and protein‐resistant property. To make patterned surfaces with protein‐resistant property for proteins, a PPEG thin film was first uniformly deposited on a glass slide and patterns were produced on the PPEG coated surface by depositing a plasma‐polymerized amine film through a metal shadow mask. When we spotted proteins on the patterned surface, they were immobilized only onto the plasma‐polymerized amine areas but not onto the PPEG areas. These results show that PPEG surfaces would be useful for the construction of various protein arrays. Copyright © 2010 John Wiley & Sons, Ltd.</P>