• 약학회지
• /
• 제50권4호
• /
• pp.278-286
• /
• 2006

Classical dihydropyrrole[3,4-f]quinazoline antifolates 7,8 and 9, in which the tricyclic ring is structurally similar to the pteridine ring of $CH_2-THF(1)$, the cofactor of thymidylate synthase (TS), were synthesized, and their in vitro antitumor activity was evaluated by measuring the cell growth inhibitory activity against cancer cell lines. The target compounds were cytotoxic against CCRF-CEM, human T-cell acute lymphoblastic leukemia, with the cell growth inhibitory activity $(IC_{50})$ of $0.8{\sim}8.3\;{\mu}M$. Among the three compounds, 3-amino analog 7 was 10- and 3.5-fold more cytotoxic compared to the 3-methyl analogs 8 and 9, and its cytotoxicity was similar to that of the reference compound with the $IC_{50}$ value of $0.83\;{\mu}M$. This result was supposed as the consequence of the fact that dihydropyrroloquinazolinone ring with amino group was able to bind well in the active site of TS. In the case of 3-methyl analogs, analog 9, which has two-carbon bridge between the dihydropyrroloquinazolinone ring and benzoyl-L-glutamic acid, was 3-times more potent in cytotoxicity than analog 8 which has one-carbon bridge, and this result indicates that the distance and conformational orientation of the benzoyl-L-glutamic acid moiety with respect to the tricyclic ring may also be a crucial determinant of cell growth inhibitory activity.

• 대한원격탐사학회지
• /
• 제19권1호
• /
• pp.61-70
• /
• 2003

This paper proposes an autonomous approach to localize the center of fiducial marks included in aerial photographs without precise geometric information and human interactions. For this localization, we present a conceptual model based on two assumptions representing symmetric characteristics of fiducial area and fiducial mark. The model makes it possible to locate exact center of a fiducial mark by checking the symmetric characteristics of pixel value distribution around the mark. The proposed approach is composed of three steps: (a) determining the symmetric center of fiducial area, (b) finding the center of a fiducial mark with unit pixel accuracy, and finally (c) localizing the exact center up to sub-pixel accuracy. The symmetric center of the mark is calculated tv successively applying three geometric filters: simplified ${\nabla}^2$G (Laplacian of Gaussian) filter, symmetry enhancement filter, and high pass filter. By introducing a self-diagnosis function based on the self-similarity measurement, a way of rejecting unreliable cases of center calculation is proposed, as well. The experiments were done with respect to 284 samples of fiducial marks composed of RMK- and RC-style ones extracted from 51 scanned aerial photographs. It was evaluated in the visual inspection that the proposed approach had resulted the erroneous identification with respect to only one mark. Although the proposed approach is based on weak constraints, being free from the exact geometric model of the fiducial marks, experimental results showed that the proposed approach is sufficiently robust and reliable.

• Journal of Korea Trade
• /
• 제23권4호
• /
• pp.131-148
• /
• 2019

Purpose - Based on the Korea-China FTA as the starting point, this paper makes an empirical analysis of the main influencing factors of the FTA utilization and performance of SMEs. Design/methodology - Taking into account the relationship between the internal and external environmental factors on FTA activities and performance of Korea's SMEs, with PLS-SEM and data obtained by the questionnaire, Smart PLS was applied for the analysis. Findings - The recognition of FTA in SMEs has a significant positive effect on FTA utilization and performance, the international marketing orientation factor only has a significant positive effect on the performance, while the inadequate improvement of non-tariff barriers has a significant negative impact on FTA utilization. In addition, FTA activity has a significant mediation effect on two paths. Originality/value - This paper is of great practical relevance as a tool to enable SMEs to make effective utilization of Korea-China FTA and improve their imports and exports. The paper helps grasp the main factors affecting the utilization and performance of FTA for SMEs, also to establish FTA Business Model and FTA utilization plans for specific industries in the future regarding tariff and non-tariffs compatibility.

• International Journal of Computer Science & Network Security
• /
• 제21권8호
• /
• pp.276-280
• /
• 2021

The article presents the concept of ICT - competence, which is considered as the most important characteristic of professional competence, which includes a combination of the following components: motivational-value (orientation of the individual to the development of his ITC-competence in future professional activities); technological (complex of skills and abilities of ICT activities); cognitive (a system of knowledge of modern technologies of future professional activity); it is determined that the pedagogical support of the formation of ICT competence of future specialists is the individualization of the process training, due to their personal and professional needs and the specifics of a regional university, providing the necessary conditions for the implementation of this process.

• 반도체디스플레이기술학회지
• /
• 제20권1호
• /
• pp.1-6
• /
• 2021

We have investigated the effect of the substrate temperature and hydrogen flow rate on the characteristics of AZO thin films for the TCO (transparent conducting oxide). For this purpose, AZO thin films were deposited by RF magnetron sputtering at room temperature and 300℃ with various H2 flow rate. Experiments were carried out while varying the hydrogen gas flow rate from 0sccm to 5.0sccm in order to see how the hydrogen gas affects the AZO thin films. AZO thin films deposited at 300℃ showed amorphous structure, whereas IZO thin films deposited at room temperature showed crystalline structure having an (222) preferential orientation. The electrical resistivity of the AZO films deposited at 300℃ was 4.388×10-3Ωcm, the lowest value. As the hydrogen gas flow rate increased, the resistivity tended to decrease.

• 정보보호학회논문지
• /
• 제18권3호
• /
• pp.61-68
• /
• 2008

본 논문에서는 지문 영상의 품질을 평가하는 새로운 방법을 제안한다. 제안한 방법은 지문 융선의 분포와 방향성, 특징점의 밀도 뿐 아니라 지문의 크기, 위치 등을 분석하여 지문 영상의 품질을 평가하게 된다. 특히 지문의 입력 위치를 분석하여 한쪽으로 치우치거나 일부만 입력된 지문을 걸러냄으로서 인식 성능을 향상시킬 수 있다. 또한 제안한 품질 평가 방법을 다양한 지문 데이터베이스에 적용하여 지문 영상의 품질과 인식 성능 간의 상관도 분석을 수행하였으며, 이를 통하여 인식 성능 향상을 위한 영상의 품질에 대한 임계값을 결정할 수 있었다.

• Journal of Korea Trade
• /
• 제25권1호
• /
• pp.133-151
• /
• 2021

Purpose - This study examines the effects of expatriate transfer on foreign affiliate's labor productivity. Design/methodology - Using Korean-owned foreign affiliate-level data, we estimate the effect of expatriate transfer on foreign affiliate's labor productivity using the system generalized method of moments model. We also consider foreign affiliate- and host country-specific contingencies and test how they are associated with expatriates in enhancing foreign affiliate's labor productivity. Findings - We consider foreign production intensity and cultural distance between the home (i.e., South Korea) and host countries as key contingencies that influence the effect of expatriates on foreign affiliate's labor productivity. We find that expatriates are effective in enhancing the labor productivity of less production-intensive foreign affiliates. This effect is strengthened as expatriates are deployed to countries that share cultural similarities with the home country. Originality/value - Considering that previous studies provide mixed results on the effect of expatriates, our findings suggest that foreign affiliate-specific operational orientation and cultural distance should be considered jointly to understand the true effect of expatriate staffing on foreign affiliate performance.

• Journal of the Korean Wood Science and Technology
• /
• 제50권5호
• /
• pp.353-364
• /
• 2022

The crystalline domain of thermosetting urea-formaldehyde (UF) resins at low formaldehyde-to-urea (F/U) molar ratios (≤ 1.0) is known to be responsible for their poor performance as wood adhesives. Crystallization has been observed in 1.0 F/U UF resins during the addition reaction stage and at the end of the synthesis process (neat UF resins). The crystallinity and X-ray diffraction (XRD) spectra of the uncured neat UF resins, on the other hand, differed significantly from those of the cured neat UF resins, raising the possibility that their crystal structures were also different. This study demonstrates for the first time that the crystalline domains in 1.0 F/U UF resins generated from uncured and cured samples are identical. Despite having a lower crystallinity value, the synchrotron XRD patterns of purified neat UF resins were equivalent to the XRD patterns of cured neat UF resins. Transmission electron microscope images of the cured UF resins showed that the crystals were lamellar structures. This finding suggests that the crystal at low molar ratio UF resins are isotropic polycrystals with random orientation.

• 한국표면공학회지
• /
• 제34권5호
• /
• pp.421-428
• /
• 2001

New WC-CrN superlattice film was deposited on Si substrate (500$\mu\textrm{m}$) using cathodic arc ion plating system. The microstructure and mechanical properties of the film depend on the superlattice period (λ). In the X-ray diffraction analysis (XRD), preferred orientation of microstructure was changed according to various superlattice periods(λ). During the Transmission Electron Microscope analysis (TEM), microstructure and superlattice period (λ) of the WC - CrN superlattice film was confirmed. Hardness and adhesion of the deposited film was evaluated by nanoindentation test and scratch test, respectively. As a result of nanoindentation test, the hardness of WC - CrN superlattice film was gained about 40GPa at superlattice period (λ) with 7nm. Also residual stress with various superlattice period (λ) was measured on Si wafer (100$\mu\textrm{m}$) by conventional beam-bending technique. The residual stress of the film was reduced to a value of 0.2 GPa by introducing Ti - WC buffer layers periodically with a thickness ratio ($t_{buffer}$/$t_{buffer+superlattice}$ ). To the end, for the evaluation of oxidation resistance at the elevated temperature, CrN single layer and WC - CrN superlattice films with various superlattice periods on SKD61 substrate was measured and compared with the oxidation resistance.

• 한국정밀공학회지
• /
• 제12권8호
• /
• pp.147-155
• /
• 1995

Recent experimental studies have been shown that strain gages can be employed to determine either static or dynamic stress intensity factors $K_{I}$ wiht relatively simple experiments. However, it does not usually provide a reliable value of stress intensity factor because of local yielding and limited regions for strain gage placement at the vicinity of the crack tip. This paper attempted to define a valid region and to indicate procedures for locating and orienting the strain gage to determine static toughness $K_{Is}$ accurately form one strain gage readings with respect to varying loadings. The strain gage methods was used for compact tension specimens made of Polycarbonate and PMMA(polymethyl methacrylate). Series expansions of the static and dynamic strain fields are applied. Strain gage orientation and location are then studied to optimize the strain response. Especially, in the dynamic experiment, the specimen employed is an oversized Charpy V-notch specimen which has been modified to provide significant constraint with a large elevation of the flow stress. The impact behavior of the specimen is monitored by placing strain gage near the crack tip. The dynamic toughness $K_{Id}$ is determined from the strain time traces of this gage.e.