• Journal of Preventive Medicine and Public Health
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• 제49권4호
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• pp.197-204
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• 2016

Objectives: In the context of the global decrease in mortality due to gastric cancer, previous studies have reported that the effect of chronic Helicobacter pylori (H. pylori) infection on the incidence of gastric cancer varies among regions. This systematic review was conducted to investigate H. pylori as a risk factor for gastric cancer in Korea, where the incidence of gastric cancer is among the highest in the world. Methods: A search strategy was established to identify articles published in Korean as well as in English. Ultimately, we included observational studies conducted among Korean patients that designed with an age-matched and sex-matched control group that reported the odds ratio associated with H. pylori. Gastric cancer cases were subdivided into overall (OGC), cardia (CGC), non-cardia (NGC), early (EGC), advanced, intestinal (IGC), and diffuse forms of gastric cancer. Summary odds ratios (SORs) with 95% confidence intervals (CIs) were calculated in the meta-analysis using a random-effect model. Results: Eleven case-control studies were ultimately selected. H. pylori was associated with an SOR of 1.81 (95% CI, 1.29 to 2.54) for OGC. Additionally, statistically significant risks were observed for CGC, NGC, EGC, and IGC. Conclusions: Chronic H. pylori infection was found to raise the risk of gastric cancer among Koreans, with the highest risk observed for CGC and EGC (SOR=2.88 for both). Follow-up clinical epidemiologic studies are needed to assess the effects of current treatments aimed at eradicating H. pylori infections.

• 한국초전도ㆍ저온공학회논문지
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• 제19권1호
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• pp.5-8
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• 2017

A series of high gradient superconducting magnetic separator (HGMS) for kaolin has been developed. It is used for processing kaolin to increase the brightness or whiteness whether it is for paper or ceramic applications. The HGMS system mainly consists of a solenoid magnet with a zero boil-off helium cryostat, a double reciprocating canisters system, and a PLC (Process Logic Controller) fully automatic control system based on SCADA (Supervisory Control and Data Acquisition) system. We have successfully developed CGC-5.5/300 and CGC-5.0/500 HGMS systems in the recent years, and now three sets of them are on-site operation in different customers. This paper will present recent progress of the HGMS system, the results of some experiments on processing kaolin clay used HGMS, and the on-site operation.

• 한국정밀공학회지
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• 제11권1호
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• pp.54-62
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• 1994

This paper presents active control methodologies to suppress structural deflections of a composite beam using a distributed piezoelectric-film actuator and sensor. Three types of different controllers are employed to achieve vibration suppression. The controllers are established depending upon the information on the velocity components of the structrue and on the deflection magnitudes as well. They are constant-amplitude controller(CAC), constant-gain mcontroller(CGC), and constant-amplitude-gain controller(CAGC). For the minimization of the residual vibration (chattering in a settled phase), which is the practical shortcoming of the conventional CAC dur to time delay phenomenon of the hardware system, a new control algoritym CAGCis designed by selecting switching constants in an optimal manner with respect to the initial tip deflection and the applied voltage. The experimental investigations of the transient and forced vibration control for the first vibrational mode are undertaken in order to compare the suppression efficiency of each control algorithm. Moreover, simultaneous controllability of various vibrational modes through the proposed scheme is also experimentally verified by pressenting both the transfer function and the phase.

• 폴리머
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• 제31권6호
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• pp.497-504
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• 2007

길이가 다른 폴리메틸렌 다리로 연결된 이핵 CGC(Constrained geometry catalyst) $[Zr({\eta}^5\;:\;{\eta}^1-C_9H_5-SiMe_2NCMe_3)Me_2]_2\;[(CH_2)_n]$ [n=6(4), 9(5), 12(6)]를 2 당량의 MeLi과 대응되는 염소화합물을 반응시켜 합성하고 이들의 구조를 확인하였다. 합성된 이핵메탈로센의 중합 특성을 에틸렌과 1-hexene의 공중합을 통해 조사하였다. 이때에 사용된 조촉매로는 일반 조촉매 $Ph_3C^+[B(C_6F_5)_4]^-\;(B_1)$과 $(B(C_6F_5)_5)_3\;(B_3)$ 그리고 이핵조촉매 $Ph_3C^+[(C_6F_5)_3B-C_6F_4-B(C_6F_5)_3]^{2-}\;(B_2)$을 이용하였다. 중합 결과 촉매의 활성은 이핵메탈로센에서는 다리길이가 길수록 크게 나타났으며, 조촉매에서는 이핵조촉매가 가장 낮은 활성을 보였다. 조촉매의 특성은 공중합체에 존재하는 가지의 함량에서 잘 나타났다. 이핵조촉매($B_2$)를 사용하면 가장 가지수가 작은 고분자가 생성되었고, 조촉매 $B_3$에서 가장 많은 가지를 가진 공중합체가 생성되었다.

• 폴리머
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• 제35권1호
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• pp.77-86
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• 2011

굳은 특성을 가진 다리로 연결된 이핵 CGC 6개의 공중합특성을 조사하였다. 6개의 화합물 중에서 3개는 길이가 다른 para-phenyl (Catalyst 1), para-xylyl (Cata1yst 2), para-diethylene phenyl (Catalyst 6) 다리를 가진 화합물이며, 나머지 3개는 다리리간드는 para-xylyl 다리 기본구조를 가졌으나 치환체가 isopropyl (Catalyst 3), n-hexyl (Cataylst 4), n-octyl (Catalyst 5)인 화합물이었다. 이핵메탈로센 6가지와 Dow 촉매를 사용하여 에틸렌과 스티렌을 공중합시켜 다리리간드의 특성변화가 촉매의 중합특성과 이로부터 생성되는 공중합체의 특성에 미치는 영향을 조사하였다. 실험 결과 다리리간드의 길이가 증가함에 따라 촉매의 중합활성이 4배까지 향상되었으며 이로부터 생성되는 공중합체의 분자량도 증가하였다. 또한 para-xylyl 리간드의 치환체가 isopropyl에서 n-hexyl 및 n-octyl로 변함에 따라 중합활성은 증가하였으나 이로부터 생성되는 분자량은 감소하였다. 본 연구 결과는 촉매구조 변화에 의한 고분자 미세구조 조절이라는 고분자 합성의 가장 어려운 부분이 이핵메탈로센을 활용하여 어느 정도 현실화될 수 있음을 보여주는 결과이다.

• Macromolecular Research
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• 제15권5호
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• pp.430-436
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• 2007

The dinuclear half-sandwich CGCs (constrained geometry catalyst) with a polymethylene bridge, $[Ti({\eta}^5 : {\eta}^1-indenyl)SiMe_2NCMe_3]_2(CH_2)_n]$[n = 6 (1) and 12 (2)], have been employed in the copolymerization of ethylene and norbornene (NBE). To compare the mononuclear metallocene catalysts; $Ti({\eta}^5 : {\eta}^1-2-hexylindenyl)SiMe_2NCMe_3$ (3), $(Cp^* SiMe_2NCMe_3)$Ti (Dow CGC) (4) and ansa-$Et(Ind)_2ZrCI_2$ (5), were also studied for the copolymerization of ethylene and NBE. It was found that the activity increased in the order: 1 < 2 < 3 < 5 < 4, indicating that the presence of the bridge between two the CGC units contributed to depressing the polymerization activity of the CGCs. This result strongly suggests that the implication of steric disturbance due to the presence of the bridge may playa significant role in slowing the activity. Dinuclear CGCs have been found to be very efficient for the incorporation of NBE onto the polyethylene backbone. The NBE contents in the copolymers formed ranged from 10 to 42%, depending on the polymerization conditions. Strong chemical shifts were observed at ${\delta}$42.0 and 47.8 of the isotactic alternating NBE sequences, NENEN, in the copolymers with high NBE contents. In addition, a resonance at 47.1 ppm for the sequences of the isolated NBE, EENEE, was observed in the $^{13}C-NMR$ spectra of the copolymers with low NBE contents. The absence of signals for isotactic dyad at 48.1 and 49.1 ppm illustrated there were no isotactic or microblock (NBE-NBE) sequences in the copolymers. This result indicated that the dinuclear CGCs were effective for making randomly distributed ethylene-NBE copolymers.

• 정보보호학회지
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• 제28권2호
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• pp.33-42
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• 2018

머신러닝 및 인공지능 기술의 발전은 다양한 분야 활용되고 있고, 이는 보안 분야에서도 마찬가지로 로그 분석이나, 악성코드 탐지, 취약점 탐색 및 대응 등 다양한 분야에서 자동화를 위한 연구가 진행되고 있다. 특히 취약점 탐색 및 대응 분야의 경우 2016년 데프콘에서 진행된 CGC를 필두로 바이너리나 소스코드 내의 취약점을 정확하게 탐색하고 패치하기 위해 다양한 연구가 시도되고 있다. 이에 본 논문에서는 취약점을 탐색 및 대응하기 위해 각 연구 별 탐색 기술과 대응 기술을 분류 및 분석한다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.159-160
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• 2006

We developed novel catalyst, PHENICS composed of the combination of a cyclopentadienyl group to perform a high catalytic activity and a bulky phenoxy group, which performs the production of high molecular weight polyolefin. The polymerization activity of PHENICS at high temperature is higher than well-known CGC catalyst. PHENICS showed the excellent ability of comonomer incorporation into polymer chain. The obtained copolymer had a high molecular weight. The PHENICS catalyst is also active to the copolymerization of ethylene and several vinyl comonomers such as styrene, norbornen, and conjugated dienes. We will discuss new cocatalysts for PHENICS to improve activity and the ability of molecular weight control.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.223-223
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• 2006

A Suzuki-coupling route is developed for preparation of ortho-phenylene-bridged Cp/amido complexes, one of which shows higher activity, higher 1-hexene incorporation, and higher molecular weight than the silylene-bridged standard CGC $[Me_{2}Si({\eta}^{5}-Me_{4}Cp)(N^{t}Bu)]TiCl_{2}$.

• Journal of Pharmaceutical Investigation
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• 제38권6호
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• pp.365-372
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• 2008

The aim of this study was to investigate the frequency of the SNPs on MDR1 exon 12, 21 and 26 in Korean population and to analyze haplotype frequency on MDR1 exon 12, 21 and 26 in Korean population. A total of 426 healthy subjects was genotyped for MDR1, using polymerase chain reaction-based diagnostic tests. Haplotype was statistically inferred using an algorithm based on the expectation-maximization (EM). MDR1 C1236T genotyping revealed that the frequency for homozygous wild-type (C/C), heterozygous (C/T) and for homozygous mutant-type (T/T) was 20.19%, 46.48% and 33.33%, respectively. MDR1 G2677T/A genotyping revealed that the frequency for homozygous G/G, heterozygous G/T, homozygous T/T, heterozygous G/A, heterozygous T/A and for homozygous A/A type was 30.75%, 42.26%, 9.86%, 7.51 %, 7.04% and 2.58%, respectively. MDR1 C3435T genotyping revealed that the frequency for homozygous wild-type (C/C), heterozygous (C/T) and for homozygous mutant-type (T/T) was 38.73%, 50.24% and 11.03%, respectively. Twelve haplotypes were observed. Of the three major haplotypes identified (CGC, TTT and TGC), the CGC haplotype were mainly predominant in the Korean populations and accounted for 29.96% of total haplotype in Korean.