• Journal of Microbiology and Biotechnology
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• 제24권10호
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• pp.1346-1353
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• 2014

In the present study, an anthraquinone derivative, questinol was successfully isolated from the broth extract of the marine-derived fungus Eurotium amstelodami for the first time. The structure of questinol was determined based on the analysis of the MS and NMR spectral data as well as comparison of those data with the published data. Moreover, the anti-inflammatory effect of questinol in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells was investigated. The results showed that questinol did not exhibit cytotoxicity in LPS-stimulated RAW 264.7 cells up to $200{\mu}M$. Questinol could significantly inhibit NO and $PGE_2$ production at indicated concentrations. Questinol was also found to inhibit the production of pro-inflammatory cytokines, including TNF-${\alpha}$, IL-1${\beta}$, and IL-6. Furthermore, the western blot analysis showed that questinol suppressed the expression level of iNOS in a dose-dependent manner. However, questinol could slightly inhibit the expression of COX-2 at the concentration of $200{\mu}M$. Therefore, our study suggests that questinol might be selected as a promising agent for the prevention and therapy of inflammatory disease.

• 한국통신학회논문지
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• 제31권11C호
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• pp.1071-1076
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• 2006

본 논문에서는 수화 인식을 위한 얼굴 및 손 추적시스템을 제안한다. 제안된 시스템은 검출 및 추적 단계로 구분된다. 검출 단계에서는 신호의 주체인 얼굴과 손에 위치한 피부 특징을 이용하였다. CbCr 공간에서의 타원 모델을 구성하여 피부 색상을 검출하고 피부 영역을 분할한다. 그리고 크기와 얼굴 특징을 이용하여 얼굴과 손 영역을 정의한다. 추적 단계에서는 동작 추정을 위하여 첫 번째 손 영역으로 예측된 다음의 손위치를 연산함으로써 두 번째 손의 영역을 유도해낸다. 그러나 갑작스런 움직임의 속도 변화가 있을 경우 연속된 프레임에서 추적된 위치는 부정확하였다. 이러한 점을 해결하고자 손 영역에 대하여 반복적인 재연산을 수행하여 적응적으로 영역을 찾음으로써 오차를 보정하도록 하였다. 실험 결과 제안된 방법은 기존의 방법보다 4%의 처리 시간이 증가된 반면, 예측 오차는 96.87%까지 감소시킬 수 있었다.

• 비파괴검사학회지
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• 제26권5호
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• pp.321-328
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• 2006

본 논문에서는 전단간섭계를 이용하여 감육 곡관부의 변형을 계측하고 내부 감육 결함의 위치를 찾고자 하였다. 전단간섭법은 비파괴검사(NDT)와 응력/변형률 해석에 적용되어왔던 광학적 방법의 한가지이다. 이 기술은 간섭계에서 tilt mirror를 조작함으로써 조절이 가능한 민감도를 갖는 변위의 1차 도함수를 직접 측정할 수 있다는 이점을 지니고 있다. 본 논문에서는, 국부적으로 감육이 발생한 탄소강 곡관부에 대해 실험하였으며, 전단간섭법을 곡관부의 변형량 측정과 내부 감육결함 검사에 적용하였다. 실험 결과로부터, 이 기술이 내부 결함이 있는 배관부에도 적용이 가능함을 확인하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.15-22
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• 2006

This paper presents a novel signal tracking algorithm for GNSS receivers using a MLE technique. In order to perform a robust signal tracking in severe signal environments, e.g., high dynamics for navigation vehicles or weak signals for indoor positioning, the MLE based signal tracking approach is adopted in the paper. With assuming white Gaussian additive noise, the cost function of MLE is expanded to the cost function of NLSE. Efficient and practical approach for Doppler frequency tracking by the MLE is derived based on the assumption of code-free signals, i.e., the cost function of the MLE for carrier Doppler tracking is used to derive a discriminator function to create error signals from incoming and reference signals. The use of the MLE method for carrier tracking makes it possible to generalize the MLE equation for arbitrary codes and modulation schemes. This is ideally suited for various GNSS signals with same structure of tracking module. This paper proposes two different types of MLE based tracking method, i.e., an iterative batch processing method and a non-iterative feed-forward processing method. The first method is derived without any limitation on time consumption, while the second method is proposed for a time limited case by using a 1st derivative of cost function, which is proportional to error signal from discriminators of conventional tracking methods. The second method can be implemented by a block diagram approach for tracking carrier phase, Doppler frequency and code phase with assuming no correlation of signal parameters. Finally, a state space form of FLL/PLL/DLL is adopted to the designed MLE based tracking algorithm for reducing noise on the estimated signal parameters.

• Journal of Biosystems Engineering
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• 제26권6호
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• pp.571-578
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• 2001

Production of green pepper has increased for ten years in Korea, as customer's preference of a pepper tuned to fiesta one. This study was conducted to develop an on-line fading algorithm of green pepper using machine vision and aimed to develop the automatic on-line grading and sorting system. The machine vision system was composed of a professive scan R7B CCD camera, a frame grabber and sets of 3-wave fluorescent lamps. The length and curvature, which were main quality factors of a green pepper were measured while removing the stem region. The first derivative of the thickness profile was used to remove the stem area of the segmented image of the pepper. A new boundary was generated after the stem was removed and a baseline of a pepper which was used for the curvature determination was also generated. The developed algorithm showed that the accuracy of the size measurement was 86.6% and the accuracy of the bent was 91.9%. Processing time spent far grading was around 0.17 sec per pepper.

• 한국주조공학회지
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• 제30권1호
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• pp.34-45
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• 2010

The effects of alloy elements and cooling rate on the solidification path and the formation behavior of $\beta$ phase in Fe-containing Al-Si alloys were studied based on the thermodynamic analysis and the pertinent experiments. The thermodynamic calculation was systematically performed by using Thermo-Calc program. For the thermodynamic analysis in high alloy region of Al-Si-Fe ternary system, a thermodynamic database for Thermo-Calc was correctly updated and revised by the collected up-to-date references. For the thermodynamic-based prediction of various solidification paths in Fe-containing Al-Si system, liquidus projection of Al-Si-Fe ternary system, including isotherms, invariant, monovariant, bivariant reactions and equilibrium temperatures, was calculated and analyzed as functions of composition and temperature. The calculated results were compared to the experimental results using various casting specimens. In order to analyze various solidification sequences as functions of Si and Fe content, 4 representative alloy compositions, low Fe content in both low and high Si contents and high Fe content again in both low and high Si contents, were designed in this study. For better understanding of the influence of cooling rate on the formation behavior of $\beta$ phase, 4 alloys were solidified under furnace and rapidly cooled conditions. Cooling curves of solidified alloys were recorded by thermal analysis. Various important solidification events were evaluated using the first derivative-cooling curves. Microstructures of the casting samples were studied by the combined analysis of optical microscopy (OM) and scanning electron microscopy (SEM).

• Near Infrared Analysis
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• 제1권2호
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• pp.21-27
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• 2000

Temperature-dependent changes in near-infrared (NIR) spectra have been measured for oleic acid, and nonanoic acid in the pure liquid state. Particular attention has been paid to the 5400-4800 cm$\^$-1/ region where a number of combination bands appear. The NIR spectra of oleic acid show that a band at 5303 cm$\^$-1/ increases with temperature while that at 5270 cm/sup-1/ decreases. It ha been found from their second derivative spectra that these spectral changes take place stepwisely with two break points at 30 and 53$\^{C}$, which correspond to the phase transition temperatures oleic acid reported previously. Principle component analysis (PCA) has been carried out for the NIR spectra of oleic acid in the 5400-4800 cm$\^$-1/ region measured over a temperature range of 15-80$\^{C}$. core plots of the first and second principal components (PCs) show that the NIR spectra are classified into three groups; the spectra measured in the temperature range of 15-30$\^{C}$, those in the range of 31-53$\^{C}$, and those in the range of 54-80$\^{C}$. These temperature ranges correspond to those for quasi-smectic liquid crystal, disordered liquid crystal, and isotropic liquid of oleic acid in the pure liquid state. In other words, PCA provides unambiguous evidence for the phase transitions. similar studies have been carried out for petroselinic acid and nonanoic acid in the pure liquid states, but they do not show any evidence for phase transitions.

• Wind and Structures
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• 제25권3호
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• pp.283-299
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• 2017

Two types of aerodynamic admittance function (AAF) that have been adopted in bridge aerodynamics are addressed. The first type is based on a group of supposed relations between flutter derivatives and AAFs. In so doing, the aero-elastic properties of a section could be used to determine AAFs. It is found that the supposed relations hold only for cases when the gust frequencies are within a very low range. Predominant frequencies of long-span bridges are, however, far away from this range. In this sense, the AAFs determined this way are of little practical significance. Another type of AAFs is based on the relation between the Theodorsen circulation function and the Sears function, which holds for thin airfoil theories. It is found, however, that an obvious illogicality exists in this methodology either. In this article, a viewpoint is put forward that AAFs of bluff bridge deck sections are inherently dependent on oncoming turbulent properties. This kind of dependence is investigated with a thin plate and a double-girder bluff section via computational fluid dynamics method. Two types of wind fluctuations are used for identification of AAFs. One is turbulent wind flow while the other is harmonic. The numerical results indicate that AAFs of the thin plate agree well with the Sears AAF, and show no obvious dependence on the oncoming wind fields. In contrast, for the case of bluff double-girder section, AAFs identified from the turbulent and harmonic flows of different amplitudes differ among each other, exhibiting obvious dependence on the oncoming wind field properties.

• 대한의생명과학회지
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• 제23권1호
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• pp.8-16
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• 2017

p-Coumaric acid is an organic compound that is a hydroxyl derivative of cinnamic acid. Due to its multiple biological activities p-coumaric acid has been widely studied in biochemical and cellular systems and is also considered as a useful therapeutic candidate for various neuronal diseases. However, the efficacy of p-coumaric acid on zebrafish developmental regulation has not been fully explored. In this study, therefore, we first investigated the action mechanism of the p-coumaric acid on the zebrafish development in a whole-organism model. p-Coumaric acid treated group significantly inhibited the pigmentation of the developing zebrafish embryos compared with control embryos without any severe side effects. In addition, p-coumaric acid down-regulated more effectively in a lower concentration than the well-known zebrafish's melanogenic inhibitor, phenylthiourea. We also compared the molecular docking property of p-coumaric acid with phenylthiourea on the tyrosinase's kojic acid binding site, which is the key enzyme of zebrafish embryo pigmentation. Interestingly, p-coumaric acid interacted with higher numbers of the amino acid residues and exhibited a tight binding affinity to the enzyme than phenylthiourea. Taken all together, these results strongly suggest that p-coumaric acid inhibits the activity of tyrosinase, consequently down-regulating zebrafish embryo pigmentation, and might play an important role in the reduction of dermal pigmentation. Thus, p-coumaric acid can be an effective and non-toxic ingredient for anti-melanogenesis functional materials.

• Plant Biotechnology Reports
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• 제2권2호
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• pp.123-131
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• 2008

Vitrification methods are convenient for cryopreserving plant specimens, as the specimens are plunged directly into liquid nitrogen (LN) from ambient temperatures. However, tissues and species with poor survival are still not uncommon. The development of vitrification solutions with high survival that cover a range of materials is important. We attempted to develop new vitrification solutions using bromegrass cells and found that VSL, comprising 20% (w/v) glycerol, 30% (w/v) ethylene glycol, 5% (w/v) sucrose, 10% (w/v) DMSO and 10 mM $CaCl_2$, gave the highest survival following cryopreservation, as determined by fluorescein diacetate staining. However, the cryopreserved cells showed little regrowth, for unknown reasons. To check its applicability, VSL was used to cryopreserve gentian axillary buds and the performance was compared with those of conventional vitrification solutions. Excised gentian stem segments with axillary buds (shoot apices) were two-step precultured with sucrose to induce osmotic tolerance prior to cryopreservation. Gentian axillary buds cryopreserved using VSL following the appropriate preculturing approach exhibited 78% survival (determined by the regrowth capacity), which was comparable to PVS2 and PVS1 and far better than PVS3. VSL had a wider optimal incubation time (20-45 min) than PVS2 and was more suitable for cryopreserving gentian buds. The optimal duration of the first step of the preculture was 7-11 days, and preculturing with sucrose and glucose gave a much higher survival than fructose and maltose. VSL was able to vitrify during cooling to LN temperatures, as glass transition and devitrification points were detected in the warming profiles from differential scanning calorimetry. VSL and its derivative, VSL+, seem to have the potential to be good alternatives to PVS2 for the cryopreservation of some materials, as exemplified by gentian buds.