• Journal of Ginseng Research
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• 제44권5호
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• pp.717-724
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• 2020

Background: Malignant arrhythmias require drug therapy. However, most of the currently available antiarrhythmic drugs have significant side effects. Ginsenoside Rg2 exhibits excellent cardioprotective effects and appears to be a promising candidate for cardiovascular drug development. So far, the oral toxicity and antiarrhythmic effects of Rg2 have not been evaluated. Methods: Acute oral toxicity of Rg2 was assessed by the Limit Test method in mice. Subchronic oral toxicity was determined by repeated dose 28-day toxicity study in rats. Antiarrhythmic activities of Rg2 were evaluated in calcium chloride-induced arrhythmic rats. Antiarrhythmic mechanism of Rg2 was investigated in arrhythmic rats and H9c2 cardiomyocytes. Results: The results of toxicity studies indicated that Rg2 exhibited no single-dose (10 g/kg) acute oral toxicity. And 28-day repeated dose treatment with Rg2 (1.75, 3.5 and 5 g/kg/d) demonstrated minimal, if any, subchronic toxicity. Serum biochemical examination showed that total cholesterol in the high-dose cohort was dramatically decreased, whereas prothrombin time was increased at Day 28, suggesting that Rg2 might regulate lipid metabolism and have a potential anticoagulant effect. Moreover, pretreatment with Rg2 showed antiarrhythmic effects on the rat model of calcium chloride induced arrhythmia, in terms of the reduced duration time, mortality, and incidence of malignant arrhythmias. The antiarrhythmic mechanism of Rg2 might be the inhibition of calcium influx through L-type calcium channels by suppressing the phosphorylation of Ca²⁺/calmodulin-dependent protein kinase II. Conclusion: Our findings support the development of Rg2 as a promising antiarrhythmic drug with fewer side effects for clinical use.

• 한국컴퓨터정보학회논문지
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• 제10권4호
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• pp.385-396
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• 2005

이 논문에서는 온라인 서명 검증에 대한 새로운 접근 방법으로, 서명을 필기의 기본 구성 요소들로 표현하는 구조적인 접근 방법을 제시한다. 속력의 국부 극소점을 분할점으로 하여 얻어지는 부분을 원시 패턴으로 정의하였고, 서브패턴으로서 방향 변화에 의해 얻어지는 단순 회전형 성분, 첨형 성분, 종형 성분의 세 가지 종류를 정의하여 서명을 구조적으로 표현하였다. 그리고 서브패턴을 기본 단위로 한 동적 계획정합 알고리듬을 제시하였다. 또한, 학습 샘플로부터 국부적인 부분에 대한 변화도와 복잡도를 추출하여 참조 패턴의 학습과 진위 판단 임계치를 설정하였다. 실험을 통하여, 함수적 접근과 매개변수적 접근 그리고 제안된 구조적 접근 방법을 동일 조건에서 검증률, 처리시간, 메모리의 측면에서 비교하였다. 제안된 방법에서는, 서명의 국부적인 가중치를 적용하고 복잡도를 판단임계치의 설정에 사용함으로써 평균 오류율이 14.2%에서 4.05%로 검증률이 크게 향상되었다. 또한, 시간과 메모리의 측면에서 함수적 접근 방법에 비해 효과적이면서도 함수적 접근 방법의 최고 성능에 근접한 검증률을 얻을 수 있었다.

• 전자공학회논문지
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• 제51권7호
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• pp.190-200
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• 2014

전 세계적으로 방송사 및 영상 관련 기관들의 비디오 기반 시스템이 디지털로 전환되고 있다. 이송 과정에서 발생하는 디지털 드롭아웃은 콘텐츠의 질을 낮추게 만든다. 게다가 디지털 드롭아웃에 초점이 맞춰진 연구가 매우 미미하며 기존 방법들로 해결하기에는 한계점이 존재한다. 상기 이유로, 우리는 디지털 드롭아웃 블록이 가지는 독특한 패턴들의 주파수 특성을 강조할 수 있도록 이산 코사인 변환 (Discrete Cosine Transform) 계수를 기반으로 하는 새로운 특징표현 방법을 제안한다. 또한, 분류를 위해 특징 벡터를 효율적으로 활용할 수 있는 SVM 기반의 오류블록 분류방법을 활용한다. 더 나아가 이 방법은 기존 방법들의 프레임 간 연속성을 이용해 발생하는 문제점들을 극복하였다. 단독 프레임의 정보만을 이용함으로써 빠른 물체의 존재하에서도 동작이 가능하고, 특정 모델이나 추정이 필요하지 않아 최소의 복잡도 하에 오류 검출이 가능하다.

• Bulletin of the Korean Chemical Society
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• 제30권1호
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• pp.35-42
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• 2009

Headspace micro solid phase extraction using mulberry paper bag (HS-MPB-$\mu$-SPE) has been developed and validated for the analysis of volatile flavor compounds from five spice by gas chromatography-mass spectrometry (GC/MS). HS-MPB-$\mu$-SPE was performed with adsorbent particles enclosed inside a mulberry paper bag. Four different kinds of adsorbents such as Tenax TA, Porapack Q, dimethylpolysiloxane and polyethylene glycol were tested. The extraction solvents compared were petroleum ether, methylene chloride, and chloroform. Better results were obtained when Tenax TA and petroleum ether were used. The limit of detection (LOD) and the limit of quantitation (LOQ) were in the range of 1.3 ng/mL and 4.3 ng/mL, respectively, for o-cymene as a model compound of monoterpene. Proposed method showed good reproducibility (3.3%, RSD) and good recoveries (94.0%). The HS-MPB- μ-SPE is very simple to use, inexpensive, rapid, requires small sample amounts and solvent consumption. Because the solvent for extraction is reduced to only a very small volume (0.6 mL), there is minimal waste or exposure to toxic organic solvent and no further concentration step. This method allows successful characterization of the headspace in contact with the five spice sample. Strong trans-anethole from star anise or fennel is a characteristic flavor of five spice powders. HS-MPB-$\mu$-SPE combined with GC/MS can be a promising technique for the broad spectrum measurement of volatile aroma compounds from solid spices.

• 한국식품과학회지
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• 제31권6호
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• pp.1563-1569
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• 1999

본 연구는 분무건조를 이용한 향기성분의 미세캡슐화를 위해 maltodextrin(MD), gum arabic(GA),alkenylsuccinated modified starch(MS), gellan gum을 피복물질로 사용하여 배합비율을 최적화하는데 목표를 갖고 수행되었다. 핵물질은 특성이 다른 5종류의 향기성분을 채종유와 1 : 4의 비율로 혼합한 flavor model system으로 사용하였다. 예비실험을 통해 핵물질 : 피복물질의 비율을 1 : 4로 하였으며, MD함량은 30%로 고정하였다. GA : MS를 $2\;:\;8{\sim}8\;:\;2$의 비율로 제조하여 유화액에서의 특성을 분석한 결과, GA : MS = 4 : 6에서 유화안정성이 우수하였으며, flavor release가 가장 적었다 이 비율에 gellan gum을 $1{\sim}5%$ 첨가하여 실험한 결과, 4% 첨가한 것이 결과가 가장 우수하였다. 이상의 결과로 MD : GA : MS : gellan gum = 30 : 26.4 : 37.6 : 4의 배합비율이 분무건조를 이용한 향기성분의 미세캡슐화를 위한 피복물질의 최적 배합조건이었다.

• 한국환경성돌연변이발암원학회지
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• 제25권4호
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• pp.157-160
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• 2005

Biofilm 내부의 항생제 내성 박테리아의 성장형태는 만성감염과 질병을 발생한다. 인위적 형성한 biofilm의 체외실험 모델 시스템 통한 항생제 침투 실험을 수행하였다. 항생제 내성 균주 (E. coli, S. aureus)는 항생제 내성균주 은행으로부터 획득하였다 Ca-alginate bead를 인위적 biofilm으로 사용하였고, 세포 생존률을 향상시키기 위해 공기 압축을 이용한 세포 포획 실험도 측정되었다. biofilm의 항생제 감수성은 항생제의 농도 따라 최저 저해 농도 (MIC)를 이용하여 측정되었다. bead생성에 따른 안정성은 bead를 형성하지 않은 세포와 비교하여 감소하였다. 항생제에 민감한 E. coli의 경우 시간이 지남에 따라 균체수도 감소하였으나, 항생제 내성 E. coli는 일정한 균체수를 유지하였다. bead형성 후 항생제 투여 효과는 항생제 내성이 있고, 낮은 농도의 항생제를 처리할수록 더 높은 생존률을 보였다.

• 한국정보과학회논문지:시스템및이론
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• 제32권7호
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• pp.333-340
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• 2005

네트워크 기반 컴퓨터 시스템이 외부 침입이나 혹은 내부 침입에 의해 부분적으로 손상 (Partially Compromised)이 되더라도 최소한의 필수 서비스를 지속적으로 제공할 수 있게 해주는 침입감내시스템(Intrusion Tolerance System) 설계에 요구되는 중요한 요소 기술 중의 하나는 컴퓨터 시스템의 정량적 신인도(Dependability) 분석이라 할 수 있다. 본 논문에서는 침입감내시스템의 방어능력을 확보하기 위해 자율컴퓨팅(Autonomic Computing)의 핵심 기술인 자가 치유(Self-healing) 메커니즘을 적용하였다. 주 서버와 보조서버로 구성된 침입감내시스템의 상태천이(State Transition)를 자가치유 메커니즘의 두 가지 요소(결함모델 및 시스템반응)를 활용하여 분석하였으며, 시뮬레이션 실험을 통해 침입감내시스템의 가용도(Availability)를 계산한 후, 두 가지 경우의 취약성(Vulnerability) 공격에 대한 사례 연구를 진행하였다.

• 수산해양기술연구
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• 제46권2호
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• pp.173-183
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• 2010

In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re $1{\mu}Pa/V$ at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re $1V/{\mu}Pa$ was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.

• Journal of Korean Neurosurgical Society
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• 제60권4호
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• pp.441-447
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• 2017

Objective : Computed tomography (CT)-based method of three dimensional (3D) analysis ($MIMICS^{(R)}$, Materialise, Leuven, Belgium) is reported as very useful software for evaluation of OPLL, but its reliability and reproducibility are obscure. This study was conducted to evaluate the accuracy of $MIMICS^{(R)}$ system, and inter- and intra-observer reliability in the measurement of OPLL. Methods : Three neurosurgeons independently analyzed the randomly selected 10 OPLL cases with medical image processing software ($MIMICS^{(R)}$) which create 3D model with Digital Imaging and Communication in Medicine (DICOM) data from CT images after brief explanation was given to examiners before the image construction steps. To assess the reliability of inter- and intra-examiner intraclass correlation coefficient (ICC), 3 examiners measured 4 parameters (volume, length, width, and length) in 10 cases 2 times with 1-week interval. Results : The inter-examiner ICCs among 3 examiners were 0.996 (95% confidence interval [CI], 0.987-0.999) for volume measurement, 0.973 (95% CI, 0.907-0.978) for thickness, 0.969 (95% CI, 0.895-0.993) for width, and 0.995 (95% CI, 0.983-0.999) for length. The intra-examiner ICCs were 0.994 (range, 0.991-0.996) for volume, 0.996 (range, 0.944-0.998) for length, 0.930 (range, 0.873-0.947) for width, and 0.987 (range, 0.985-0.995) for length. Conclusion : The medical image processing software ($MIMICS^{(R)}$) provided detailed quantification OPLL volume with minimal error of inter- and intra-observer reliability in the measurement of OPLL.

• Steel and Composite Structures
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• 제33권1호
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• pp.19-36
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• 2019

Cyclic behaviour of composite (steel-concrete) plate shear walls (CPSW) with variable column flexural stiffness is experimentally and numerically investigated. The investigation included design, fabrication and testing of three pairs of one-bay one-storey CPSW specimens. The reference specimen pair was designed in way that its column flexural stiffness corresponds to the value required by the design codes, while within the other two specimen pairs column flexural stiffness was reduced by 18% and 36%, respectively. Specimens were subjected to quasi-static cyclic tests. Obtained results indicate that column flexural stiffness reduction in CPSW does not have negative impact on the overall behaviour allowing for satisfactory performance for up to 4% storey drift ratio while also enabling inelastic buckling of the infill steel plate. Additionally, in comparison to similar steel plate shear wall (SPSW) specimens, column "pull-in" deformations are less pronounced within CPSW specimens. Therefore, the results indicate that prescribed minimal column flexural stiffness value used for CPSW might be conservative, and can additionally be reduced when compared to the prescribed value for SPSWs. Furthermore, finite element (FE) pushover simulations were conducted using shell and solid elements. Such FE models can adequately simulate cyclic behaviour of CPSW and as such could be further used for numerical parametric analyses. It is necessary to mention that the implemented pushover FE models were not able to adequately reproduce column "pull-in" deformation and that further development of FE simulations is required where cyclic loading of the shear walls needs to be simulated.