• 한국군사과학기술학회지
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• 제25권2호
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• pp.135-143
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• 2022

In this paper, the compact waveguide slot array antenna for interferometric radar altimeter is proposed. The proposed antenna structure consist of corrugation structure which is applied between each channel to improve isolation, three-channel waveguide slot array antenna and feeder. In addition, to reduce the occurrence of phase ambiguity, the baseline spacing of the three-channel antenna is analyzed and the results are applied to the design. For compact design, reduced height and SMP connector structure are used and the dip brazing method which is the conjugation method after dipping to flux is used for the fabrication of the lightweight antenna. The measurement result of the proposed antenna shows less than 1.41 : 1 (VSWR) and 48.3 dBc (isolation). The antenna gain is higher than 20.2 dBi and the side lobe levels are lower than 18.8 dB (vertical plane) and 10.0 dB (horizontal plane).

• 전자공학회논문지
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• 제51권1호
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• pp.24-30
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• 2014

디지털 역지향성 안테나 시스템은 사전정보 없이 입사된 신호를 신호의 위상을 추정하여 추정한 각도만큼 다시 돌려서 신호가 수신된 방향으로 재전송하는 시스템이다. 디지털 역지향성 안테나는 모든 방향에 대해 전력을 송출해야 하는 무지향성 안테나에 비해 신호가 수신된 방향으로 신호를 재전송하기 때문에 입사된 방향으로 신호가 집중되어 지향성이 높아지므로 전력의 소모를 줄일 수 있다. 일반적으로 디지털 역지향성 안테나는 다중경로 환경에서 단일 안테나 시스템에 비해 좋은 성능을 보이는 것으로 알려져 있지만, 심각한 ISI의 영향에서는 성능의 저하가 일어난다. 본 논문에서는 이러한 문제점을 극복하기 위해 심각한 ISI의 보상이 가능한 터보등화기를 결합하여 역지향성 안테나를 제안하였다. 제안하는 터보등화기를 이용한 디지털 역지향성 안테나를 통해 심각한 ISI 환경에서의 BER 성능을 개선하였다.

• 한국항행학회논문지
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• 제22권3호
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• pp.240-245
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• 2018

전체 광 중계 구간 모두 불규칙한 분산 계수를 갖는 단일 모드 광섬유와 분산 보상 광섬유 (DCF; dispersion compensating fiber)를 이용한 융통적인 분산 제어 링크 구조를 제안하였다. 링크의 융통적 구성은 각 전송 반 구획에서 DCF의 분산 계수를 기준으로 이들을 인위적으로 분포시켜서 가능하게 하였다. 광 위상 공액기 전의 전송 반 구획에서는 DCF의 분산 계수를 점진적으로 증가시키고, 광 위상 공액기 다음의 전송 반 구획에서는 DCF의 분산 계수를 점진적으로 감소시키는 'AD' 분포에서 왜곡된 파장 분할 다중(WDM; wavelength division multiplexed) 신호가 최상으로 보상되는 것을 확인하였다. 따라서 왜곡된 WDM 채널의 보상 효과를 더욱 증가시키기 위해서는 광섬유의 길이, 중계 구간 당 잉여 분산뿐만 아니라 광섬유의 분산 계수에 상관없이 'AD' 분포를 선택할 필요가 있다는 것을 확인하였다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.191-191
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• 1998

It has been hypothesized that formation of oxygen-derived free radicals may play an important part in ischemically induced tissue injury. In this study, the effects of vitamin C treatment on hepatic reperfusion model were investigated. Livers isolated from 18 hrs fasted rats were subjected to low flow hypoxia (1 $m\ell$/g liver/min, for 45min) followed by reoxygenation (for 30min). The perfusion medium used was Krebs-Henseleit bicarbonate buffer (KHBB, pH 7.4) and vitamin C (0.25, 0.5, 1.0 and 2.0 mM) was added to perfusate. 7-Ethoxycoumarin was used as substrate of phase and metbolism. After hypoxia oxygen consumption significantly dropped but vitamin C 0.25, 0.5 and 1.0 mM treatments restored oxygen consumption to the level of control group. LDH and lipid peroxidation were not changed in all experimental groups. Oxidation, phase metabolism, significantly decreased following hypoxia but improved during reoxygenation. Vitamin C 0.25 mM treatment significantly improved the oxidation of 7-ethoxycoumarin during hypoxia and reoxygenation, but the oxidation significantly decreased by vitamin C 2.0 mM treatment. Similarly, sulfate conjugation decreased in hypoxic group, but this decrease was inhibited by vitamin C 0.25, 0.5 and 1.0 mM treatments. Our findings suggest that hypoxia/reoxygenation diminishes hepatic drug metabolizing function, vitamin C at concentration of 0.25-1.0 mM ameliorates but at higher concentration aggravates these hypoxia/reoxygenation-induced changes.

• 한국통신학회논문지
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• 제38A권2호
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• pp.209-216
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• 2013

본 논문에서는 저전력 고품질의 60GHz 대역 무선 통신을 위한 디지털 역지향성 안테나 시스템의 설계와 성능을 분석하였다. 디지털 역지향성 안테나는 수신된 방향에 대한 정보 없이 자동적으로 빔을 신호원 방향으로 생성할 수 있다. 제안된 시스템은 신호원 방향으로 빔을 형성하여 간섭 신호를 감소시키고 SINR 을 향상시킴으로써 저전력 통신이 가능하다. 초고속 통신을 위해서 60GHz 와 같은 밀리미터파 대역에서 통신을 할 경우 주파수 오프셋이 심하게 발생된다. 본 논문에서는 디지털 PLL 을 사용하여 주파수 오프셋에 강한 시스템을 설계하였다. 또한, 안테나 수에 따른 빔 성능 및 디지털 역지향성 안테나의 위상 공액 기법을 사용한 경우에 대해서 주파수 오프셋을 고려하여 성능을 분석하였다.

• Genomics & Informatics
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• 제16권3호
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• pp.52-58
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• 2018

In this report, we present a case study of how pharmacogenomics and pharmacometabolomics can be useful to characterize safety and pharmacokinetic profiles in early phase new drug development clinical trials. During conducting a first-in-human trial for a new molecular entity, we were able to determine the mechanism of dichotomized variability in plasma drug concentrations, which appeared closely related to adverse drug reactions (ADRs) through integrated omics analysis. The pharmacogenomics screening was performed from whole blood samples using the Affymetrix DMET (Drug-Metabolizing Enzymes and Transporters) Plus microarray, and confirmation of genetic variants was performed using real-time polymerase chain reaction. Metabolomics profiling was performed from plasma samples using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. A GSTM1 null polymorphism was identified in pharmacogenomics test and the drug concentrations was higher in GSTM1 null subjects than GSTM1 functional subjects. The apparent drug clearance was 13-fold lower in GSTM1 null subjects than GSTM1 functional subjects (p < 0.001). By metabolomics analysis, we identified that the study drug was metabolized by cysteinylglycine conjugation in GSTM functional subjects but those not in GSTM1 null subjects. The incidence rate and the severity of ADRs were higher in the GSTM1 null subjects than the GSTM1 functional subjects. Through the integrated omics analysis, we could understand the mechanism of inter-individual variability in drug exposure and in adverse response. In conclusion, integrated multi-omics analysis can be useful for elucidating the various characteristics of new drug candidates in early phase clinical trials.

• 한국응용과학기술학회지
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• 제31권3호
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• pp.367-374
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• 2014

In this study, skin permeation enhancement was confirmed by designing it to have a structure and composition similarity to the intercellular lipids that improve miscibility with skin by cross-linked lipids poloxamer. The cross-linked lipids poloxamer was synthesized and analyzed by 1H NMR that structure dose had conjugated pluronic with ceramide3. Active component is released by modification of liquid crystal structure because PPO part, large-scale molecule block of pluronic, has hydrophobic nature at skin temperature of $35^{\circ}C$. Conjugated pluronic with ceramide3 was synthesized using Pluronic F127 and p-NPC (4-nitrophenyl chloroformate) at room temperature yielded 89%. Pluronic(Ceramide 3-conjugated Pluronic) was synthesized by reaction of p-NP-Pluronic with Ceramide3 and DMAP. The yield was 51%. This cross-linked lipids poloxamer was blended and dissolved at isotropic state with skin surface lipids, phospholipid, ceramide, cholesterol and anhydrous additive solvent. Next step was preceded by ${\alpha}$-Transition at low temperature for making the structure of Meso-Phase Lamella, and non-hydrous skin analogue liquid crystal using thermo-sensitivity smart sensor, lamellar liquid crystal structure through aging time. For confirmation of conjugation thermo-sensitivity smart sensor and non-hydrous skin analogue liquid crystal, structural observation and stability test were performed using XRD(Xray Diffraction), DSC(Differential Scanning Calorimetry), PM (Polarized Microscope) And C-SEM (Cryo-Scanning Electron Microscope). Thermo-sensitivity observation by Franz cell revealed that synthesized smart sensor shown skin permeation effect over 75% than normal liquid crystal. Furthermore, normal non-hydrous skin analogue liquid crystal that not applied smart sensor shown similar results below $35^{\circ}C$ of skin temperature, but its effects has increased more than 30% above $35^{\circ}C$.

• Archives of Pharmacal Research
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• 제22권2호
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• pp.99-107
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• 1999

A series of organosulfur compounds were synthesized with the aim of developing chemopreventive compounds active against hepatotoxicity and chemical carcinogesis. 2-(Allylthio) prazine (2-AP) was effective in inhibiting cytochrome P450 2E1-mediated catalytic activities and protein expression, and in inducing microsomal epoxide hydrolase and major glutathione S-transferases. 2-AP reduced the hepatotoxicity caused by toxicant sand elevated cellular GSH content. Development of skin tumors, pulmonary adenoma and aberrant crypt foci in colon by various chemical carcinogens was inhibited by 2-AP pretreatment. Anticarcinogenic effects of 2-AP at the stage of initiation of tumors were also observed in the aflatoxin B1 ($AFB_1$)-induced three-step medium-term hepatocarcinogenesis model. Reduction of $AFB_1$-DNA adduct by 2-AP appeared to result from the decreased formation of $AFB_1$-8,9-epoxide via suppression of cytochrome P450, while induction of GST 2-AP increases the excretion of glutathione-conjugated $AFB_1$ . 2-AP was a radioprotective agent effective against the lethal dose of total body irradiation and reduced radiation-induced injury in association with the elevation of detoxifying gene expression. 2-AP produces reactive oxygen species in vivo, which is not mediated with the thiol-dependent production of oxidants and that NF-KB activation is not involved in the induction of the detoxifying enzymes. the mechanism of chemoprotection by 2-AP may involve inhibition of the P450-mediated metabolic activation of chemical carcinogens and enhancement of electrophilic detoxification through induction of phase II detoxification enzymes which would facilitate the clearance of activated metabolites through conjugation reaction.

• 환경분석과 독성보건
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• 제21권4호
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• pp.243-251
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• 2018

Pharmaceuticals in wastewater effluents have been recognized as emerging pollutants threatening freshwater organisms. To extend understanding for bioaccumulation and toxicity in those organisms, information on biotransformation products (or metabolites) and their metabolic pathway are crucial. The aim of the present study is to identify and elucidate metabolites of pharmaceuticals formed in exposed organisms using suspect and nontarget screening approach using LC-HRMS. As the target pharmaceuticals, carbamazepine, ketoprofen, metoprolol, propranolol, and verapamil were selected whereas Daphnia magna and Gammarus pulex were used as test organisms. After 24h exposure, metabolites formed in the organisms were identified using LC-HRMS. The structures of metabolites were elucidated via analysis of MS/MS fragment pattern and the comparison with fragment database. As the results, a total of 10 metabolites were identified for 5 parent compounds (C253/C356 for carbamazepine, K211 for ketoprofen, M256 for metoprolol, P218/P276/P306 for propranolol, V196/V291/V441 for verapamil). Among them, the presence of C253 and V291 was confirmed using standard materials. Most of the identified metabolites were formed through oxidative reactions such as hydroxylation, N-demethylation, and dealkylation. Cysteine conjugation (phase II reaction) metabolite (C356) for carbamazepine was found in daphnia. The metabolic pathway of verapamil showed similar metabolic pathways and metabolic pathways for both species. Although the toxicological information on the identified metabolites could not be confirmed, the molecular structure information of the proposed metabolites can be used for future evaluation and prediction of toxicity.

• Fisheries and Aquatic Sciences
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• 제27권5호
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• pp.314-328
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• 2024

The mechanism for the elimination of xenobiotics undergoes three different phases of reactions in organisms. Among these, glutathione S-transferases (GSTs) are classified as phase II detoxification enzymes, catalyzing the conjugation of electrophilic substrates to glutathione or reduced hydroperoxides. This study aimed to investigate the molecular characteristics, detoxification functions, and immune responses of GST omega (LhGSTO1) and kappa (LhGSTK1) in redlip mullet. The open reading frames of LhGSTO1 (720 bp) and LhGSTK1 (687 bp) encoded proteins of 239 and 228 amino acids, respectively. Sequence analysis revealed that LhGSTO1 and LhGSTK1 possessed GSH-binding sites in their N-terminal domains. Substrate-binding sites in the C-terminal domain were exclusively identified in LhGSTO1. In the tissue-specific transcription profile analysis, both LhGSTO1 and LhGSTK1 were ubiquitously expressed in all tissues of healthy mullets. Temporal expression analysis of LhGSTO1 and LhGSTK1 in the blood showed that their expression was significantly modulated by polyinosinic:polycytidylic (poly I:C), lipopolysaccharide (LPS), and Lactococcus garvieae. Different chemical and cellular assays were performed to assess the detoxification and cellular protective abilities of the two proteins. A substrate specificity test using the recombinant proteins revealed that both proteins possessed specific activity toward 1-chloro-2,4-dinitrobenzene (CDNB). In the disk diffusion assay, the smallest clearance zones were observed for LhGSTO1 and LGSTK1 against CdCl₂. In the cell protection assay, both LhGSTO1 and LhGSTK1 showed significant Cd detoxification ability compared to the control. Collectively, these results demonstrate that GST omega and kappa are involved in host defense against immune stimulants and xenobiotics in redlip mullet.