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- 검색키워드
- 저자 : Lee Joonhee (검색결과 173 건)
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Current status and management of fluvalinate resistance of Varroa mites in Korea
Susie Cho,Joonhee Lee,Youngcheon Lim,Jonghyeok Lee1,Si Hyeock Lee 한국응용곤충학회 2023 한국응용곤충학회 학술대회논문집 Vol.2023 No.10
The Varroa mite, Varroa destructor is an ectoparasite that parasitizes honey bees. The widespread usage of acaricides, particularly fluvalinate, has resulted in the emergence of resistance in Varroa mite populations all over the world. The goal of this study is to track fluvalinate resistance in Varroa mite field populations in Korea using both bioassay and molecular markers. To accomplish this, a residual contact vial (RCV) bioassay for on-site resistance monitoring was developed. Early mortality evaluation in the RCV bioassay was effective for reliably separating mites with the knockdown resistance (kdr) genotype, but late mortality evaluation was useful for distinguishing mites with additional resistance factors. The RCV bioassay of 14 field mite populations collected in 2021 revealed potential resistance development in four populations. Quantitative sequencing was used as an alternate method to examine the frequency of the L925I/M mutation in the voltage-gated sodium channel (vgsc), which is related with the fluvalinate kdr phenotype. While the mutation was not present in Varroa mite populations in 2020, it appeared in 2021, rose in frequency in 2022, and was practically ubiquitous across the country by 2023. This recent emergence and rapid spread of fluvalinate resistance within a span of three years demonstrate the Varroa mite's significant potential for developing resistance. This situation emphasizes the critical necessity to replace fluvalinate with alternate acaricides, such as fenpyroximate, coumaphos, and amitraz. A few novel vgsc mutations potentially involved in resistance were identified. Potential factors driving the rapid expansion of resistance were further discussed.
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Development of an infant formula certified reference material for the analysis of organic nutrients
Lee, Joonhee,Kim, Byungjoo,Lee, Sun Young,Choi, Jongoh,Kang, Dukjin,Lee, Hwasim,Choi, KiHwan,Lee, Hyeyoung,Sim, Hee-Jung,Baek, Song-Yee,Lee, Honghee,Hyung, Seok-Won,Ahn, Seonghee,Seo, Dongwon,Hwang, J Applied Science Publishers 2019 Food chemistry Vol.298 No.-
<P><B>Abstract</B></P> <P>Infant formula certified reference material (CRM, KRISS CRM 108-02-003) were developed for the analysis of organic nutrients. The CRM is a milk-based infant formula powder, packaged at 14 g per unit. Ten thousand units were prepared and stored at −70 °C. For the certification of each nutrient, ten units were analyzed for simultaneous value-assignment and homogeneity test. Analytical methods used were isotope dilution mass spectrometry (IDMS) based on liquid chromatography mass spectrometer (LC/MS) or gas chromatography mass spectrometer (GC/MS) as higher-order reference methods.13 vitamins, 3 fatty acids, and total cholesterol were certified. The between-unit relative standard deviation of measurement results for each nutrient ranged 0.2% to 2.5%, showing very good homogeneity. The expanded relative uncertainties of the certified values ranged from 1% to 8%, indicating that they have higher-order metrological quality. The values of proximates (proteins, lipids, carbohydrates, water, and ash) were assigned through inter-laboratory comparisons.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An infant formula CRMs for the analysis of organic nutrients was developed. </LI> <LI> Organic nutrients were certified by IDMS approaches as higher-order reference methods. </LI> <LI> Homogeneities and stability of the CRM were evaluated by IDMS approaches. </LI> <LI> Metrological qualities of the certified values were proved by their small uncertainties. </LI> <LI> Five proximates were value-assigned by interlaboratory comparison. </LI> </UL> </P>
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Lee, Joonhee,Kim, Byungjoo Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.11
A mass balance method for purity assessment of thermolabile organic reference materials was established by combining several techniques, including liquid chromatography with UV/VIS detector (LC-UV), Karl-Fischer (K-F) Coulometry, and thermal gravimetric analysis (TGA). This method was applied to three fluoroquinolones like enrofloxacin, norfloxacin and ciprofloxacin. LC-UV was used to analyze structurally related organic impurities based on UV/VIS absorbance spectra obtained in combination with LC separation. For all three organic reference materials, the UV/VIS spectra of the separated impurities were similar to that of the major component of the corresponding materials. This indicates that the impurities are structurally related to the respective reference material sharing common chromophores. Impurities could be quantified by comparing their absorbances at the wavelength of maximum absorbance (${\lambda}_{max}$). The water contents of the reference materials were measured by K-F Coulometry by an oven-drying method. The total inorganic impurities contents were assayed from ash residues in TGA analysis with using air as a reagent gas. The final purities estimated from results of those analytical techniques were assigned as ($99.91{\pm}0.06$), ($97.09{\pm}0.17$) and ($91.85{\pm}0.17$)% (kg/kg) for enrofloxacin, norfloxacin and ciprofloxacin, respectively. The assigned final purities would be applied to the reference materials which will be used as calibrators for the certification of those compounds in matrix CRMs as starting points for the traceability of their certified values to SI units.
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Lee, Joonhee,Kim, Byungjoo Korean Society for Mass Spectrometry 2017 Mass spectrometry letters Vol.8 No.3
Ibuprofen is one of the most popular analgesic and antipyretic drugs. An isotope dilution mass spectrometry method based on LC/MS was developed as a candidate reference method for the accurate determination of ibuprofen in pharmaceutical tablets. Isotope labelled ibuprofen, $ibuprofen-d_3$, was added as an internal standard into sample extracts. Ibuprofen and $ibuprofen-d_3$, was analysed by LC/MS in a selected ion monitoring (SIM) mode to detect ions at m/z 205 and 208, respectively. The repeatability and reproducibility of the developed ID-LC/MS method were tested for the validation and assessment of metrological quality of the method.
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Lee, Jaeick,Lee, Seunghwa,Kim, Byungjoo,Lee, Joonhee,Kwon, Oh-Seung,Cha, Eunju Korean Society for Mass Spectrometry 2018 Mass spectrometry letters Vol.9 No.1
A quantitation method for free amino acids in human serum was developed using a stepwise-dilution method and a bimodal cation exchange (CEX)/hydrophilic interaction liquid chromatography (HILIC)-tandem mass spectrometry system equipped with an electrospray ionization source (ESI/MS/MS). This method, which was validated using quality control samples, was optimized for enhanced selectivity and sensitivity. Dithiothreitol (DTT) was used as a reducing agent to prevent the oxidation of a serum sample ($50{\mu}L$), which was then subjected to stepwise dilution using 3, 30, and 90 volumes of acetonitrile containing 0.1% formic acid. Chromatographic separation was performed on an Imtakt Intrada Amino Acid column ($50mm{\times}3mm$, $3{\mu}m$) in mixed mode packed with CEX and HILIC ligands embedded in the stationary phase. Underivatized free amino acids were eluted and separated within 10 min. As a result of the validation, the precision and accuracy for the inter- and intraday assays were determined as 2.11-11.51% and 92.82-109.40%, respectively. The lowest limit of quantification (LLOQ) was $0.5-4.0{\mu}g/mL$ and the matrix effect was 80.22-115.93%. The proposed method was successfully applied to the quantitative analysis of free amino acids in human serum.
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Joonhee Lee,Hyunjun Lee,Minkwang Lee,Myoungho Sunwoo 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
This paper proposes a nonlinear sliding mode observer for exhaust pressure estimation. A precise estimation of the exhaust pressure is important for the control of a variable geometry turbocharger (VGT) and exhaust gas recirculation (EGR) system. In order to estimate the exhaust pressure accurately, we derive nonlinear dynamic models of the intake and exhaust pressure in diesel engines based on the energy and mass conservation laws. The model parameters which vary with the engine operating conditions are modeled through an empirical approach to consider physical phenomenon of each component. We develop the nonlinear sliding mode observer for the exhaust pressure estimation to deal with nonlinear dynamics of the diesel engine air system. The stability of the proposed observer is guaranteed by the Lyapunov stability criterion. Moreover, the estimation performance is improved by adding a damping term into the observer. The proposed observer is implemented in a real-time embedded system and the experimental results represent that the observer estimates exhaust pressure precisely in both steady and transient engine operating conditions.
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Joonhee Lee,Dong-Ho Kim,Jaehoon Kim,전헌수 한국물리학회 2009 Current Applied Physics Vol.9 No.3
As an approach to enhance light extraction from GaN-based light-emitting diodes (LEDs), we inserted a submicron period photonic crystal (PC) pattern at the interface between GaN epilayer and sapphire substrate. A two-dimensional square-lattice pillar array of 600-nm period was produced directly onto the sapphire substrate by a combination of laser holography and inductively-coupled-plasma etching. A standard GaN LED heterostructure was grown on top of the nano-patterned substrate, which was then processed to conventional bottom-emitting LED chips. At the drive current of 20 mA, the PC-LED produced surface-normal output power about 40% higher than that of the reference LED (with no PC integrated). Temperature-dependent photoluminescence measurement indicated that the emission enhancement was solely a structural effect by the integrated PC pattern.
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Lee, JoonHee 대한물리치료학회 2020 대한물리치료학회지 Vol.32 No.1
Purpose: This study examined the level of self-esteem and awareness of sexual harassment among college students majoring in physical therapy to discover the status of sexual harassment and the types of and responses to sexual harassment at clinical training sites. Methods: The study participants included 195 college students majoring in physical therapy in Gyeonggi and Chungcheong provinces, who responded fully to the survey questionnaire. The data were prepared through self-reporting on a structured questionnaire and collected from September to November 2018. Results: The difference in the mean value of self-esteem was evident between the two groups investigated. The most common types of sexual harassment were verbal, visual, and physical. The types of damage reported by the participants were emotional, physical, and social. The group of participants who experienced sexual harassment had a high rate of avoidance, while the group of participants who did not experience sexual harassment exhibited a high rate of coping. Conclusion: The incidence of verbal sexual harassment was reported to be significantly higher, and the emotional damage was the most serious. Students should be provided with more specific and realistic preventive education or countermeasures so they can respond more proactively to real situations.
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