• The Korean Journal of Physiology
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• 제30권1호
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• pp.85-96
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• 1996

Adenosine and its analogues are known to possess analgesic effects and to be involved in the opiate-induced antinociception as well. This study was designed to investigate the effects of three adenosine agonists, 5'- (N-cyclopropyl) -carboxamidoadenosine(CPCA), 5'-N-ethylcarboxamidoadeno-sine (NECA) and $N^6-cyclohexyladenosine$ (CHA) on the signal transmission in the spinal cord and also to elucidate mechanisms of their actions in the anesthetized cat. All the tested adenosine agonists(i.v,) exerted inhibitory effects on the responsiveness of the wide dynamic range (WDR) cells, the inhibitory action of CHA, an adenosine $A_1$ receptor agonist, $(80{\mu}g/Kg)$ being most weak. The intravenous CPCA, an adenosine $A_2$ receptor agonist, $(20{\mu}g\;/Kg)$ and NECA, nonspecific adenosine receptor agonist, $(20{\mu}g\;/Kg)$ inhibited the responses of WDR cells to pinch and C fiber stimulation more strongly than those to brush and A fiber stimulation. CPCA (i.v.) also suppressed the responses of WDR cells to thermal stimulus. And all the CPCA-induced inhibitions were caffeine-reversible. When CPCA was directly applied onto the spinal cord or intravenously administered into the spinal cat, on average, about three quarters of the CPCA-induced inhibitory effect was abolished. On the other hand, in the animal with spinal lesions in the ipsilateral dorsolateral area, the CPCA-induced inhibition was comparable to that observed in the spinal cats. In conclusion, this study shows that adenosine agonists strongly suppress the responses of WDR cells to pinch, C fiber stimulation and thermal stimuli mainly through the supraspinal adenosine $A_2-receptors$.

• Journal of Microbiology and Biotechnology
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• 제16권10호
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• pp.1605-1612
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• 2006

Interleukin (IL)-18, a member of the family of IL-l cytokine, is one of the principal inducers of $interferon-{\gamma}(IFN-{\gamma})$ in T lymphocytes and natural killer cells. The objective of the present study was to evaluate the effect of IL-18 on the expression of chemokine IP-10 (CXCL-10) mRNA in mouse peritoneal macrophages. IL-18 had very weak direct effect or synergistic effect with IL-12 on the expression of IP-10 mRNA in C57BL/6 mouse peritoneal macrophages. However, IL-18 pretreatment was found to playa cooperative role in the expression of lipopolysaccharide (LPS)-induced IP-10 mRNA. For the expression of LPS-induced IP-10 mRNA, the synergistic effect was detected after 16 h of IL-18 pretreatment prior to LPS stimulation. The expression level of CD14 in cells stimulated with LPS was not changed by IL-18 pretreatment, and the level of $IFN-{\gamma}$ production during IL-18 pretreatment plus LPS stimulation was barely discernible ($0.36{\pm}0.31pg/ml$). Namely, the synergistic effect of IL-18 pretreatment was not related to a change of LPS receptor, CD14 expression, and the production of $IFN-{\gamma}$ by the interaction between IL-18 and LPS. The synergistic effect of IL-18 pretreatment on the expression of LPS-induced IP-10 was related to not NF-kB but AP-1 activation, and associated with the extracellular signal-regulated kinase (ERK) pathway, one of the mitogen-activated protein kinase signaling pathways. These results provide useful information that may elucidate the mechanisms underlying the effect of IL-18 on the expression of IP-10 mRNA.

• 한국항공우주학회지
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• 제45권5호
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• pp.409-416
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• 2017

공중의 비행체에 필요한 정보를 전달하는 광대역 송신시스템은 근거리에서 동시에 운용될 수 있도록 다수의 부채널 주파수를 확보하고 있다. 취약한 외부환경에 노출되는 송신기의 경우, 시스템의 신뢰성을 높이기 위하여 안테나를 포함하여 다른 내부의 하위 구성품들의 자체고장진단을 할 수 있도록 설계되어야 한다. 안테나 자체고장진단은 보통의 경우 안테나 반사세기를 기준으로 판정 내리는데, 증폭단과 안테나가 긴 길이의 케이블로 연결될 경우는 안테나 반사세기가 주파수마다 많은 차이가 발생된다. 본 논문에서는 증폭단과 안테나의 연결에 사용되는 케이블 길이에 따라 안테나 반사세기가 주기성을 갖는 현상을 이론적으로 살펴보고, 반사세기 반복주기를 기반으로 점검주파수 범위설정, 다수 주파수 설정 점검 등을 이용하여 효과적인 안테나 고장진단 방법에 대하여 제시한다.

• Journal of Astronomy and Space Sciences
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• 제19권4호
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• pp.377-384
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• 2002

GPS L1 반송파 위상을 이용한 실시각 정밀측위 알고리즘(Real-time Phase DAta Processor: RPDAP)을 개발하고, 이를 기존의 L1 RTK(Real Time Kinematic) 측위정밀도와 비교하였다. 기존의 L1 RTK 기법은 관측환경에 매우 민감한 반면, RPDAP은 공통관측위성의 검색에 있어서 고도각이 낮거나 신호세기가 약한 위성을 제외함으로써 안정적인 결과를 산출할 수 있었다. RPDAP은 저가의 수신기를 이용하여 GPS 위상자료 측위기법을 실시각 응용분야에 적용하기 위한 것으로, 본 연구를 통한 L1 RTK기법과의 정밀도 비교·분석을 통해 RPDAP 알고리즘의 장·단점을 검토하고 향후 실용화를 위한 개선방안에 대해 논의하고자 한다. 향후 RPDAP과 함께 이동체의 고정밀 항법이나 개인위치추적 등에 RPDAP을 활용할 계획이다.

• 한국정밀공학회지
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• 제27권6호
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• pp.82-89
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• 2010

Ankle-foot orthosis with an artificial pneumatic muscle which is intended for the assistance of plantarfelxion torque was developed. In this study, power pattern of the device in the various pneumatics and the effectiveness of the system were investigated. The pneumatic power was provided by ankle-foot orthosis controlled by user‘s physiological signal, that is, muscular stiffness in soleus muscle. This pneumatic power can assist plantarflexion torque of ankle joint. The subjects performed maximal voluntary isokinetic plantarflexion motion on a biodexdynamometer in different pneumatics, and they completed three conditions: 1) without wearing the orthosis, 2) wearing the orthosis with artificial muscles turned off, 3) wearing the orthosis activated under muscular stiffness control. Through these experiments, we confirmed the effectiveness of the orthosis and muscular stiffness control using the analyzing isokinetic plantarflexion torque. The experimental results showed that isokinetic torques of plantarflexion motion of the ankle joints gradually increased in incremental pneumatic. The effectiveness of the orthosis was -7.26% and the effectiveness of the muscular stiffness control was 17.83% in normalized isokinetic plantarflexion torque. Subjects generated the less isokinetic torques of the ankle joints in wearing the orthosis with artificial muscles turned off, but isokinetic torques were appropriately reinforced in condition of wearing the orthosis activated under muscular stiffness control(17.83%) compared to wearing the orthosis(-7.26%). Therefore, we respect that developed powered orthosis is applied in the elderly that has weak muscular power as the rehabilitation equipment.

• Bulletin of the Korean Chemical Society
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• 제19권6호
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• pp.654-660
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• 1998

$[Fe^{II}Fe^{III}BPLMP(OAc)_2](BPh_4)_2$ (1), a new model for the reduced form of the purple acid phosphatases, has been synthesized by using a dinucleating ligand, 2,6-bis[((2-pyridylmethyl)(6-methyl-2-pyridylmethyl)amino) methyl]-4-methylphenol (HBPLMP). Complex I has been characterized by X-ray diffraction method as having (μ-phenoxo)bis(acetato)diiron core. Complex 1 was crystallized in the monoclinic space group C2/c with the following cell parameters: a=41.620(6) Å, b=14.020(3) Å, c=27.007(4) Å, β=90.60(2)°, and Z=8. The iron centers in the complex 1 are ordered as indicated by the difference in the Fe-O bond lengths which match well with typical $Fe^{III}-O\; and\; Fe^{II}-O$ bond lengths. Complex 1 has been studied by electronic spectral, NMR, EPR, SQUID, and electochemical methods. Complex 1 exhibits strong bands at 592 nm, 1380 nm in $CH_3CN$ (ε = 1.0 × 103 , 3.0 × 102). These are assigned to $phenolate-to-Fe^{III}$ and intervalence charge-transfer transitions, respectively. Its NMR spectrum exhibits sharp isotropically shifted resonances, which number half of those expected for a valence-trapped species, indicating that electron transfer between $Fe^{II}\;and\;Fe^{III}$ centers is faster than NMR time scale. This complex undergoes quasireversible one-electron redox processes. The $Fe^{III}_2/Fe^{II}Fe^{III}\;and\;Fe^{II}Fe^{III}/Fe^{II}_2$ redox couples are at 0.655 and -0.085 V vs SCE, respectively. It has $K_{comp}=3.3{\times}10^{12}$ representing that BPLMP/bis(acetate) ligand combination stabilizes a mixed-valence $Fe^{II}Fe^{III}$ complex in the air. Complex 1 exhibits a broad EPR signal centered near g=1.55 which is a characteristic feature of the antiferromagnetically coupled high-spin $Fe^{II}Fe^{III}$ system $(S_{total}=1/2)$. This is consistent with the magnetic susceptibility study showing the weak antiferromagnetic coupling $(J= - 4.6\;cm^{-1},\; H= - 2JS_1{\cdot}S2)$ between $Fe^{II}\; and \;Fe^{III}$center.

• Steel and Composite Structures
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• 제21권6호
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• pp.1183-1210
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• 2016

Viscoelastic sandwich structures (VSSs) are widely used in mechanical equipment, but in the service process, they always suffer from aging which affect the whole performance of equipment. Therefore, aging state recognition of VSSs is significant to monitor structural state and ensure the reliability of equipment. However, non-stationary vibration response signals and weak state change characteristics make this task challenging. This paper proposes a novel method for this task based on adaptive second generation wavelet packet transform (ASGWPT) and multiwavelet support vector machine (MWSVM). For obtaining sensitive feature parameters to different structural aging states, the ASGWPT, its wavelet function can adaptively match the frequency spectrum characteristics of inspected vibration response signal, is developed to process the vibration response signals for energy feature extraction. With the aim to improve the classification performance of SVM, based on the kernel method of SVM and multiwavelet theory, multiwavelet kernel functions are constructed, and then MWSVM is developed to classify the different aging states. In order to demonstrate the effectiveness of the proposed method, different aging states of a VSS are created through the hot oxygen accelerated aging of viscoelastic material. The application results show that the proposed method can accurately and automatically recognize the different structural aging states and act as a promising approach to aging state recognition of VSSs. Furthermore, the capability of ASGWPT in processing the vibration response signals for feature extraction is validated by the comparisons with conventional second generation wavelet packet transform, and the performance of MWSVM in classifying the structural aging states is validated by the comparisons with traditional wavelet support vector machine.

• 한국전자통신학회논문지
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• 제13권6호
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• pp.1333-1342
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• 2018

지금까지 뇌파(Electroencephalography - EEG)는 뇌전증 진단 및 치료를 위한 가장 중요하고 편리한 방법이었다. 그러나 뇌전증 뇌파 신호의 파형 특성은 매우 약하고 비 정지 상태이며 배경 노이즈가 강하기 때문에 식별하기가 어렵다. 이 논문에서는 간질 뇌파의 특징 선택을 통한 차원 감소를 통한 분류 방법의 효과를 분석한다. 우리는 차원 감소를 위해 주 요소 분석, 커널 요소 분석, 선형 판별 분석 방법을 사용하였다. 차원 감소방법의 성능 분석을 위해 Support Vector Machine: SVM), Logistic Regression(: LR), K-Nearestneighbor(: K-NN), Decision Tree(: DR), Random Forest(: RF) 분류 방법들을 사용해 평가하였다. 실험 결과에 따르면, PCA는 SVM, LR 및 K-NN에서 75% 정확도를 나타냈다. KPCA는 SVM과 K-KNN에서 85%의 성능을 보였으며 LDA는 K-NN를 이용했을 때 100 %의 정확도 보여주었다. 따라서 LDA를 이용한 차원 감소가 뇌전증 EEG 신호에 대한 최고의 분류 결과 보여주었다.

• 융합보안논문지
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• 제20권4호
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• pp.217-225
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• 2020

최근 "사회적 거리 두기"로 인해 해외 여행객이 대폭 감소하는 반면 개인의 안전과 보안을 위해 CCTV나 전기경보 및 신호장치, 전기진단 및 의료기기에 대한 관심과 수요가 증가할 것으로 기대하고 있다. 본 논문의 목적은 공항 환승여객과 CCTV, 전기진단 및 의료기기, 전기경보 및 신호장치의 수출이 한국 수출에 미치는 영향을 살펴보면서 각 변수별 동조화현상을 찾아보는데 있다. 이를 위해 본 연구에서는 통계청 국가통계포털과 관세청 수출입 무역통계에서 2000년 1월부터 2020년 04월까지 총 231개 월별자료를 이용하였다. 실증분석결과, CCTV와 전기진단 및 의료기기의 수출이 한국 수출에 상대적으로 높은 동조화현상을 보여주었다. 전기경보 및 신호장치의 수출과 환승여객이 수출액과 일정 수준 동조화현상을 보여주었으나 상대적으로 약하게 나타났다.

• Journal of Korean Neurosurgical Society
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• 제65권4호
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• pp.572-581
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• 2022

Objective : Compared to microscopes, exoscopes have advantages in field-depth, ergonomics, and educational value. Exoscopes are especially well-poised for adaptation into fluorescence-guided surgery (FGS) due to their excitation source, light path, and image processing capabilities. We evaluated the feasibility of near-infrared FGS using a 3-dimensional (3D), 4 K exoscope with near-infrared fluorescence imaging capability. We then compared it to the most sensitive, commercially-available near-infrared exoscope system (3D and 960 p). In-vitro and intraoperative comparisons were performed. Methods : Serial dilutions of indocyanine-green (1-2000 ㎍/mL) were imaged with the 3D, 4 K Olympus Orbeye (system 1) and the 3D, 960 p VisionSense Iridium (system 2). Near-infrared sensitivity was calculated using signal-to-background ratios (SBRs). In addition, three patients with brain tumors were administered indocyanine-green and imaged with system 1, with two also imaged with system 2 for comparison. Results : Systems 1 and 2 detected near-infrared fluorescence from indocyanine green concentrations of >250 ㎍/L and >31.3 ㎍/L, respectively. Intraoperatively, system 1 visualized strong near-infrared fluorescence from two, strongly gadolinium-enhancing meningiomas (SBR=2.4, 1.7). The high-resolution, bright images were sufficient for the surgeon to appreciate the underlying anatomy in the near-infrared mode. However, system 1 was not able to visualize fluorescence from a weakly-enhancing intraparenchymal metastasis. In contrast, system 2 successfully visualized both the meningioma and the metastasis but lacked high resolution stereopsis. Conclusion : Three-dimensional exoscope systems provide an alternative visualization platform for both standard microsurgery and near-infrared fluorescent guided surgery. However, when tumor fluorescence is weak (i.e., low fluorophore uptake, deep tumors), highly sensitive near-infrared visualization systems may be required.