• Korean Journal of Optics and Photonics
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• v.7 no.1
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• pp.77-86
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• 1996

We employ the SOR method to analyze CPW electrodes of Ti:$LiNbO_3$ Mach-Zehnder traveling-wave optical modulator in the tapered region of an optical modulator. In the tapered region of the modulator, we design the electrodes satisfying $Z_c=50{\Omega}$. In the modulation region, we find two find sets of design parameters. One set is for $Z_c=50{\Omega}$, $n_{eff}=2.26$ and the another is for $n_{eff}=2.2$, $Z_c=47.7{\Omega}$.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.32-44
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• 1983

In case of $K_{Imax}$ < $K_{Iscc}$, the corrosion fatigue of high strength steel in 0.1N $H_{2}$S $O_{4}$ solution and 3.5% salt water is as follows. 1. The fatigue life shortens in order of 3.5% salt water and 0.1N $H_{2}$S $o_{4}$ solution. 2. The fatigue crack growth rate in air is obtained as the following equation. (dc/dN)$_{atr}$=7.23*10$^{-6}$ (.DELTA. K)$^{2.23}$ 3. The corrosion fatigue crack growth rate in environment is divided into three regions, that is, First Region, Second Region and Third Region from the small cyclic stress intensity. 4. The formation rate of the active surface on metal is slower than the mechano-chemical reaction rate in First Region. The crack growth rate depends on time and the cyclic stress intensity and is expressed as the following equation. (dc/dN)$_{I}$=C(/DELTA. K)$^{\delta}$ 5. The formation rate of the active surface is faster than the mechano-chemical reaction rate in Second Region and the synergistic effect by stress and corrosion becomes slow. In case the fatigue load is large, we have the critical crack growth rate which is not related to the cyclic stress intensity. 6. The corrosion crack growth rate by the mechano-chemical reaction is the same in $H_{2}$S $O_{4}$ solution and salt water, so Hydrogen accelerates the crack growth. 7. The environment has no effect on the corrosion fatigue crack growth rate in Third Region. 8. In First Region and Second Region, dimple is observed on the fatigue fracture surface in 0.1N $H_{2}$S $O_{4}$ solution. 9. The striation is observed in any environment as in air in Third Region and its interval approximately coincide with the crack growth rate.ate.e.e.

• 전기의세계
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• v.27 no.4
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• pp.45-51
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• 1978

A new method of realizing the field effect transistor with a sub-.mu. channel width is described. The sub-.mu. channel width is made possible by etching grooves into n$^{+}$ pn$^{[-10]}$ n$^{[-10]}$ structure and using p region at the wall for the channel region of the Metal-Oxide-Semiconductor transistor (MOST), or by diffusing two different types of impurities through the same diffusion mask and using p region at the surface for the channel region of MOST. When the drain voltage is increased at the pn$^{[-10]}$ drainjunction the depletion layer extends into the n$^{[-10]}$ region instead of into p region; this is also the secret of success to realize the sub-.mu. channel width. As the result of the experimental fabrication, a microwave MOST was obtained. The cut-off frequency was calculated to be 15.4 GHz by Linvill's power equation using the measured capacitances and transconductance.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.100-105
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• 1994

Analytical expressions for the breakdown voltage and the optimum drift region length (L$_{dr}$) of SOI (Silicon-On-Insulator) pn diodes are derived in terms of the doping concentration and the thickness of the n- drift region and the buried oxide thickness. The optimum L$_{dr}$ is obtained from the condition that the breakdown voltage of the vertical electric field of n+n- junction equals to the of the lateral electric field of n+n-p+ junction. Analytical results agree reasonably with the numerical simulations using PISCESII.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.22
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• pp.9955-9960
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• 2014

Background: Promoter hypermethylation is a common event in human cancer. O6-methylguanine-DNA methyltransferase (MGMT) is a gene involved in DNA repair, which is methylated in a variety of cancers. We aimed to explore the methylation status of MGMT gene among the North Eastern population where esophageal cancer incidence and exposure to carcinogens like nitrosamines is high. Materials and Methods: A total of 100 newly diagnosed esophageal cancer cases along with equal number of age, sex and ethnicity matched controls were included in this study. Methylation specific PCR was used to determine the MGMT methylation status in serum samples. Results: Aberrant promoter methylation of the MGMT gene was detected in 70% of esophageal cancer cases. Hypermethylation of MGMT gene was found to be influenced by environmental factors like betel quid and tobacco which contain potent carcinogens like nitrosamines. Tobacco chewing and tobacco smoking habit synergistically with MGMT methylation elevated the risk for esophageal cancer development [adjusted OR=5.02, 95% CI=1.35-18.74; p=0.010 for tobacco chewing and Adjusted OR=3.00, 95% CI=1.22-7.36; p=0.014 for tobacco smoking]. Conclusions: Results suggest that the DNA hypermethylation of MGMT is an important mechanism for MGMT gene silencing resulting in esophageal cancer development and is influenced by the environmental factors. Thus MGMT hypermethylation can be used as a biomarker for esophageal cancer in high incidence region of North East India.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10653-10658
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• 2015

Background: A very high incidence of lung cancer is observed in Mizoram and Manipur, North East India. We conducted a population based case control study to establish associations of p53 codon 72 polymorphisms and interactions with environmental factors for this high incidence. Material and Methods: A total of 272 lung cancer cases and 544 controls matched for age (${\pm}5years$), sex and ethnicity were collected and p53 codon 72 polymorphism genotypes were analyzed using a polymerase chain based restriction fragment length polymorphism assay. We used conditional multiple logistic regression analysis to calculate adjusted odds ratios and 95% confidence intervals after adjusting for confounding factors. Results: p53 Pro/Pro genotype was significantly associated with increased risk of lung cancer in the study population (adjusted OR=2.14, CI=1.35-3.38, p=0.001). Interactions of the p53 Pro/Pro genotype with exposure to wood smoke (adjusted OR=3.60, CI=1.85-6.98, p<0.001) and cooking oil fumes (adjusted OR=3.27, CI=1.55-6.87, p=0.002), betel quid chewing (adjusted OR=3.85, CI=1.96-7.55, p<0.001), tobacco smoking (adjusted OR=4.42, CI=2.27-8.63, p<0.001) and alcohol consumption (adjusted OR=3.31, CI=1.10-10.03, p=0.034) were significant regarding the increased risk of lung cancer in the study population. Conclusions: The present study provided preliminary evidence that a p53 codon 72 polymorphism may effect lung cancer risk in the study population, interacting synergistically with environmental factors.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10691-10695
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• 2015

Background: Association of angiotensin converting enzyme (ACE) gene polymorphisms with lung cancer susceptibility remains uncertain and varies with ethnicity. Northeast India represents a geographically, culturally, and ethnically isolated population. The area reports an especially high rate of tobacco usage in a variety of ways of consumption, compared with the rest of the Indian population. Materials and Methods: We conducted a population based case control study in two major high risk region for lung cancer from Northeast India. A total of 151 consecutive lung cancer cases diagnosed histopathologically and equal numbers of controls were recruited with record of relevant sociodemographic information. Blood samples were collected and processed to identify ACE gene polymorphism. Results: Significantly higher (40.4 % vs 29.1%, OR=1.97, CI=1.04-3.72; p=0.037) prevalence of the ACE II genotype was observed among lung cancer cases. Smoking was significantly associated with increased risk of lung cancer (OR=1.70, CI=1.02-2.81; p=0.041). An enhanced risk was also observed for interaction of ACE II genotype with tobacco smoking (OR=4.09, CI=1.51-11.05; p=0.005) and chewing (OR=3.68, CI=1.22-11.13; p=0.021). Conclusions: The present study indicates significant association s of the ACE II genotype with lung cancer in high risk Northeast India.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3C
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• pp.329-340
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• 2009

This paper proposes a novel code tracking scheme to track the fine code synchronization for BOC(pn,n) modulated spreading signals. The correlation function of BOC(pn,n) modulated spreading signals has been several peaks. In this paper, we observe that the correlation function in the advanced offset region remains almost unchanged, due to the multipath signals being received later than a line-of-sight signal. Based on this observation, we propose a novel code tracking scheme which is called the advanced region correlation (ARC) method for BOC(n,n) modulated spreading signals. And, we compare with the code tracking accuracy between the conventional and proposed methods in the static multipath and land mobile satellite system channels through the Monte-Carlo simulation. Then, base on the proposed scheme, we propose the generalized-ARC (ARC) scheme for BOC(pn, n) modulated spreading signals.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.58-58
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• 2003

The envelope glycoprotein of HIV, gp41, mediates the membrane fusion with human cells. The extracellular domain of gp41 has two helical regions. The N-terminus helical region (N-helix) forms trimeric coiled coil, interacts with the C-terminus helical region (C-helix) of gp41 to form a stable helical bundle structure. In this study, we have shown that the N-helix of gp41 has membrane interacting and disrupting abilities. It was localized into the interface of the lipidic phase and head group of the membrane. In contrast, the N-helix region with membrane fusion defective mutations could not bind to membrane. In addition, the N-helix bound on the membrane was released from the membrane by the C-helix, and the complex of the N- and C-helix did not interact with membrane. These results suggested that the membrane binding ability of the N-helix is necessary for the fusion activity of gp41, and such property is possibly controlled by the C-helm.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.367-373
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• 2009

Regional variation in the fatty acid content of shellfish was investigated on 5 species of Korean shellfish including murex shell, ark shell, jack-knife clam, orient hard clam, and little neck clam that were originated from 2 geographically different regions in Korea (Region 1: South coast, $34-35^{\circ}N$, $127-129^{\circ}E$; Region 2: West coast, $36-38^{\circ}N$, $126-127^{\circ}E$). Significant regional difference in total fatty acids content was observed in murex shell and little neck clam (p<0.01), but not in the other species of shellfish. The contents of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids including n-3 and n-6 fatty acids were appreciably higher in murex shell from Region 2 and in little neck clam from Region 1 than the shellfish originated from their counterpart areas (p<0.05). Nevertheless, relative percentages of the fatty acids remained constant within same species regardless of geographic regions or species. Considering the facts of that the fish/shellfish are unique sources of n-3 fatty acids and a little neck clam is the most-consumed shellfish in Korea, n-3 fatty acids intake might vary with the habitat of the shellfish that Koreans consume.