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Jiho Lee,Tae Sung Lee,Oh Jun Kwon,Haigun Lee,Tae Kuk Ko IEEE 2014 IEEE transactions on applied superconductivity Vol.24 No.3
<P>This paper deals with the low-pass filtering characteristic of the axial magnetic field of no-insulation and partial-insulation high temperature superconducting (HTS) coils carrying a dc-biased ac current. Recently, the no-insulation winding technique has been issued as a key technique to enhance the performance of HTS coils in terms of the overall current density, thermal stability, and mechanical integrity. In this paper, to verify the effect of time-varying external distortion on no-insulation HTS coils, an experimental analysis is carried on three HTS coils-insulation, no-insulation, and partial-insulation coils. To simulate the environment in which time-varying external distortion influences the HTS coils, a dc-biased ac current is carried by the HTS coils. The axial magnetic fields of no-insulation, partial insulation, and insulation HTS coils are experimentally tested and analyzed. When the coils carry a dc-biased ac current, the no-insulation and partial-insulation coils have a tendency to attenuate the high-frequency components and to act as a low-pass filter on the axial magnetic field; however, the insulation coil does not attenuate the high-frequency components of the axial magnetic field. The analysis of the experimental results can be useful data for the adoption of no-insulation and partial-insulation windings in superconducting applications.</P>
Validation protocol for whole-body dosimetry in an agricultural exposure study
Lee, Jiho,Kim, Eunhye,Shin, Yongho,Lee, Jonghwa,Lee, Junghak,Maasfeld, Wolfgang,Kim, Jeong-Han The Korean Society for Applied Biological Chemistr 2018 Applied Biological Chemistry (Appl Biol Chem) Vol.61 No.1
Agricultural workers exposed to pesticides can experience adverse health impacts depending on toxicity and exposure amount. Whole-body dosimetry (WBD) is the most reliable, practical, and realistic method for measuring exposure. Since validation of analytical and experimental methodologies is critical for quantitative determination of exposure, we conducted a validation procedure to design an essential protocol for WBD exposure studies. Using the fungicide kresoxim-methyl, matrixmatched standards were prepared with various matrices including outer cloth, inner cloth, washing solution for gloves and hands, gauze, and glass fiber filter (IOM sampler) to determine the instrumental limit of quantitation for high-performance liquid chromatography (HPLC) (2 ng) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) (10 pg). Method limits of quantitation (MLOQ) were also set for HPLC (0.1 mg/L) and LC-MS/MS (0.005 mg/L). We observed good analysis repeatability (coefficient of variation < 6%), and the linearity of the calibration curves was reasonable ($r^2$ > 0.998) in the range of 0.001-10 mg/L in various matrices. Recovery tests were carried out at three levels of concentration (MLOQ, 10 MLOQ, and 100 MLOQ) and resulted in good recoveries (72.7-105.6%). We did not observe breakthrough of the compound in tests of holding capacity for glass fiber pesticide filters. The procedures established in the present study are applicable as an essential, comprehensive protocol for exposure assessment studies using WBD.
Lee, Jiho,Lee, Jaehan,Ahn, Jaewuk,Jo, Kyusik,Hong, Sung Pil,Kim, Choonsoo,Lee, Changha,Yoon, Jeyong American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.40
<P>Desalination technologies have heavily been investigated to utilize the abundant salt water on Earth due to the global freshwater shortage. During recent years, the desalination battery (DB) has attracted attention for its low-cost, eco-friendly, and energy-efficient characteristics. However, the current DB system is subject to inevitable performance degradation because of the mass-transfer limitation at the electrode-electrolyte interface, particularly when the system is used to treat brackish water. Here, we present a novel strategy to overcome the intrinsic mass-transfer limitation of DB in brackish water using an effective cell design based on a multichannel flow system. Compared to the conventional DB that consists of one feed channel, the multichannel desalination battery (MC-DB) is configured using two side channels introducing a highly concentrated solution to the electrodes and one middle feed channel for water desalination. The MC-DB showed a desalination capacity of 52.9 mg g<SUP>-1</SUP> and a maximum salt removal rate of 0.0576 mg g<SUP>-1</SUP> s<SUP>-1</SUP> (production rate of 42.3 g m<SUP>-2</SUP> h<SUP>-1</SUP>) when a salinity gradient between the feed streams in the middle (10 mM NaCl) and side (1000 mM NaCl) channels was present, which were 3-fold higher than those in the case with no salinity gradient. In addition, the high concentration solution in the side channel significantly enhanced the rate capability of MC-DB, allowing the system to operate under a high current density of 40 A m<SUP>-2</SUP> with a desalination capacity of 34.1 mg g<SUP>-1</SUP>. Considering the effect of electrolyte concentration on the battery electrode performance through electrochemical characterization, the highly saline medium at the side channel in the MC-DB creates an optimal environment for the battery electrode to fully capitalize the high desalination capacity, salt removal rate, and capacity retention of the battery electrodes.</P> [FIG OMISSION]</BR>
GC-ECD/NPD를 이용한 축산물 중 잔류농약 동시 다성분 기기분석조건 확립
이지호 ( Jiho Lee ),이종화 ( Jonghwa Lee ),최훈 ( Hoon Choi ),신용호,이정학 ( Junghak Lee ),정민우 ( Min Woo Jung ),백수진 ( Sujin Baek ),김정한 ( Jeong-han Kim ) 한국환경농학회 2016 한국환경농학회 학술대회집 Vol.2016 No.-
본 연구에서는 GC를 이용하여 현행 식품공전의 축산물 잔류농약시험법 대상 농약 대부분을 통합 분석할 수 있는 새로운 신속 다종농약 다성분 분석체계를 개발하여 축산물 잔류농약 분석기술의 선진화, 간편화 및 체계화에 그 목적이 있다. 축산물에 잔류허용기준이 설정된 농약 92 성분 중 물리화학적 특성과 기술적 검토를 통하여 GC로 분석이 가능한 75 성분에 대하여 GC-ECD/NPD 분석을 수행하였다. 분석기기 조건은 식품공전 상 다종농약 다성분 분석법 4.1.2.2법을 기반으로 이를 변형하여 확립하였다. 개별 성분들의 ECD 및 NPD 분석을 통해, 75 성분 중, ECD 검출가능 성분 41종, NPD 검출가능 성분 24종, 검출이 불가능한 성분 10종을 확인하였고, 각 성분들의 머무름 시간(Retention time)을 확인하였으며, 컬럼오븐조건의 변화를 통하여 ECD 2 그룹(21 성분, 20 성분), NPD 2 그룹(13 성분, 11 성분)으로 그룹화하였다. 그룹화 완료 후, 각 그룹별로 혼합용액을 조제하고 기기상 검출한계(Limit of detection)를 확인하기 위해 이들을 단계적으로 희석하여 GC-ECD/NPD에 주입하여 크로마토그램상의 시그날 대 노이즈 비율(Signal to Noise rate)을 기준으로 검출한계를 설정하였다. 기기상 검출한계는 0.01 mg/kg 35종, 0.02 mg/kg 10종, 0.05 mg/kg 11종, 0.1 mg/kg 5종, 0.2 mg/kg 1종, 0.5 mg/kg 3종으로 설정하였다. 이를 토대로 각 농약의 잔류허용기준 (Maximum Residue Limits, MRL) 수준의 검출을 위하여 전처리법에서의 농축배수는 최소 2배 이상 필요함을 확인할 수 있었다. 본 연구결과에서 얻은 기기조건을 토대로 축산물시료(소, 돼지, 닭, 계란, 우유)에서의 잔류농약 분석을 위한 기기분석 조건으로 유용하게 활용될 수 있을 것으로 판단된다.
Jang-Ho Lee,Joon-Soo Lee,Woo-Saeng Kwon,Je-Yong Kang,Dong-Yun Lee,Jun-Gyo In,Yun-Soo Kim,Jiho Seo,In-Ho Baeg,Il-Moo Chang,Keith Grainger 고려인삼학회 2015 Journal of Ginseng Research Vol.39 No.2
Background: Ginseng (Panax ginseng Meyer) is an important medicinal herbs in Asia. However, ginsengvarieties are less developed. Method: To developed ginseng varieties, a pure line selection method was applied in this study. Results: Gumpoong was testing of 4-yr-old specimens in 2002, the proportions of the below-groundroots that were rusty colored for Gumpoong was 1.29 in Daejeon and 1.45 in Eumseong, whereas theproportions for its yellow berry variant were 2.60 and 2.45 in the two regions, respectively. Thus theGumpoong was resistant to root rust. Sunpoong has a high yielding property. Its average root weight is70.6 g for 6-yr-old roots. Its yield is 2.9 kg/1.62m2 and the rate of heaven- and earth-grade product is20.9%, which is very high compared to 9.4% for Yunpoong. Sunone is resistance to root rot and thesurvival rate of 4-yr-old roots was 44.4% in 1997, whereas that of the violet-stem variant landrace was21.7%. Sunhyang has content of arginyl-fructosyl-glucose (AFG), which produces the unique scent of redginseng, is 95.1 mmol/g and greater than the 30.8 mmol/g of Chunpoong in 6-yr-old plants. Sunun andCheongsun are being nurtured to protect genetic resources. Conclusion: Developed ginsneg varieties will be used as the basis for the protection of genetic resourcesand breeding. Jang-Ho Lee