• JSTS:Journal of Semiconductor Technology and Science
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• 제3권2호
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• pp.63-68
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• 2003

The DC and RF characteristics of $In_{0.5}Ga_{0.5}P/In_{0.22}Ga_{0.78}As/GaAs$ p-HEMTs with a gate oxide layer of various thicknesses ($50{\;}{\AA},{\;}300{\;}{\AA}$) were investigated and compared with those of a Schottky-gate p-HEMT without the gate oxide layer. A prominent improvement in the breakdown voltage characteristics were observed for a p-HEMT having a gate oxide layer, which was implemented by using a liquid phase oxidation technique. The on-state breakdown voltage of the p-HEMT having the oxide layer of $50{\;}{\AA}$was ~2.3 times greater than that of a Schottky-gate p-HEMT. However, the p-HEMT having the gate oxide layer of $300{\;}{\AA}$ suffered from a poor gate-control capability due to the drain induced barrier lowering (DIBL) resulting from the thick gate oxide inspite of the lower gate leakage current and the higher on-state breakdown voltage. The results for a primitive p-HEMT having the gate oxide layer without any optimization of the structure and the process indicate the potential of p-HEMT having the gate oxide layer for high-power applications.

• 전기학회논문지
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• 제63권11호
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• pp.1571-1574
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• 2014

In this paper, we propose a unidirectional transmission of critical information obtained by keyboard hacking or kernel and keyboard driver hacking even though the computer is not connected to the external network. We show the hacking can be attempted in the proposed method to show the way preventing such attempts in advance. Firewalls and other various methods are used to prevent the hacking from the external network but the hacking is also attempted in various ways to detour the firewall. One of the most effective way preventing from the hacking attack is physically disconnect the internal intranet systems from the external internet and most of the government systems, military systems and big corporate systems are using this way as on one of the protection method. In this paper, we show the feasibility of transmission of security codes, etc via the short message to the external network on the assumption that a hacking program such as Trojan Horse is installed on the computer systems separated from the external network. Previous studies showed that the letters on the monitor can be hijacked by electromagnetic analysis on the computer to obtain the information even though the system is not connected ti the network. Other studies showed that the security code hint can obtained by analyzing the power consumption distribution of CPU. In this paper, the power consumption distribution of externally accessible power line is analyzed to obtain the information and the information can be transmitted to the external network. Software controlling the CPU and GPU usage is designed to control the power supply of computer. The sensors such as the Rogowski coils can be used on the external power line to collect the data of power consumption change rates. To transmit the user password by short message, due to the capacitive components and the obstacle from other power supply, A very slow protocol are used.

• Journal of Microbiology and Biotechnology
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• 제19권11호
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• pp.1393-1400
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• 2009

A bacteriocin-producing strain PI80 was isolated from the gut of Penaeus indicus (Indian white shrimp) and identified as Streptococcus phocae PI80. The bacteriocin was purified from a culture supernatant to homogeneity as confirmed by Tricine SDS-PAGE. Reverse-phase HPLC analysis revealed a single active fraction eluted at 12.94 min, and MALDI-TOF mass spectrometry analysis showed the molecular mass to be 9.244 kDa. This molecular mass does not correspond to previously described streptococcal bacteriocins. The purified bacteriocin was named phocaecin PI80 from its producer strain, as this is the first report of bacteriocin production by Streptococcus phocae. The bacteriocin exhibited a broad spectrum of activity and inhibited important pathogens: Listeria monocytogenes, Vibrio parahaemolyticus, and V. fischeri. The antibacterial substance was also sensitive to proteolytic enzymes: trypsin, protease, pepsin, and chymotrypsin, yet insensitive to catalase, peroxidase, and diastase, confirming that the inhibition was due to a proteinaceous molecule (i.e., the bacteriocin), and not due to hydrogen peroxide or diacetyl. Phocaecin PI80 moderately tolerated heat treatment (up to $70^{\circ}C$ for 10 min) and resisted certain solvents (acetone, ethanol, and butanol). A massive leakage of $K^+$ ions from E. coli $DH5\alpha$, L. monocytogenes, and V. parahaemolyticus was induced by phocaecin PI80, as measured by Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES). Therefore, the results of this study show that phocaecin PI80 may be a useful tool for inhibiting L. monocytogenes in seafood products that do not usually undergo adequate heat treatment, whereas the cells of Streptococcus phocae PI80 could be used to control vibriosis in shrimp farming.

• Journal of Chest Surgery
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• 제27권12호
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• pp.1015-1022
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• 1994

Over the past few years, video-assisted thoracic surgery [VATS] has been used increasingly for intrathoracic pathologic problems as a less invasive operative techniques. Today it is viewed as a sparing and safe alternative to thoracotomy for a wide spectrum of indications. Using video-assisted operative thoracoscopy, we performed consecutive 150 operations on 148 patients during the initial 2 years of our experience from July 1992 with the following indications: pneumothorax [n=53], hyperhidrosis [n=29], mediastinal mass [n=23], pleural disease [n=13], diffuse parenchymal or interstitial lung disease [n=12], benign pulmonary nodule [n=7], metastatic lung mass [n=3], primary lung cancer [n=3], bronchiectasis [n=2], malignant pericardial effusion [n=2], endobronchial tuberculosis [n=1], esophageal achalasia [n=1], and pulmonary parenchymal foreign body [n=1]. There were no death, and overall complicaton rate was 24.0%[n=36]. The most prevalent complication was persistent air leakage [longer than 5 days] in 14 cases [9.3%]. Persistent pleural effusion [longer than 5 days] occurred in 6 cases [4.0%]. Six patients were converted to an open thoracotomy because of inability to control the operative bleeding [n=3], failed adhesiolysis in bronchiectasis [n=2], and radical excision of an lung cancer [n=1]. Pneumothorax recurred in 3 cases[2.0%]. Other complications were Horner`s syndrome, diaphragm tears, temporary phrenic nerve palsy, hoarseness, subsegmental atelectasis, transient respiratory difficulty, and esophageal mucosal tear. The advantages of this minimally traumatizing operative technique lie in improved visualization, decreased pain, shortened hospital stay, and less postoperative morbidity. The indications of VATS has been extended increasingly to intrathoracic pathologies, but its role in the managements of primary lung cancer and esophageal disease remains to be defined.

• Tribology and Lubricants
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• 제36권5호
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• pp.253-261
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• 2020

In this paper, we present an experimental investigation of the frequency characteristics and a visual inspection of an oxidizer pump with a modified rear-floating ring seal for a 7-tonf turbopump. An oxidizer pump typically operates at high rotational speeds and under cryogenic conditions. Despite its low hydraulic efficiency, the floating ring seal is frequently employed as a leakage control solution for turbomachinery because it effectively reduces abrasion by friction. When the oxidizer pump starts up, the floating ring moves excursively but locks up stably against the pump casing when the contact pressure increases. The compressive force on the floating ring depends on the hydrodynamic forces induced by the flow through the floating ring. This force is controlled by the nose position of the floating ring. Based on a validation test for a 7-tonf turbopump with two types of floating rings, we concluded that the floating ring with a small diameter nose can move easily with a low contact pressure in the cooling path. This leads to instability of the pressure fluctuation around the floating ring. In contrast, a floating ring with a large diameter nose has a high contact pressure and attaches strongly to the casing, which causes wear and frictional oxidation between the contact surfaces of the impeller and the floating ring.

• 대한기계학회논문집A
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• 제35권11호
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• pp.1445-1451
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• 2011

공기압 밸브는 자동화 시스템에 공급되는 공기를 제어하는 기능을 지닌 핵심부품으로 널리 사용되고 있다. 하지만 공기압 밸브가 고장이 발생하면 설치되는 시스템의 특성상 전체 시스템에 영향을 미쳐 막대한 손실을 야기 시킬 수 있다. 이로 인하여 최근 신뢰성에 대한 중요성 및 소비자의 요구수준이 날로 증대되고 있어 밸브의 수명을 예측하여 제품의 신뢰성을 확보하기 위한 수명분포, 수명열화 특성 등과 같은 연구가 널리 진행되고 있다. 따라서 본 논문에서는 공기압 밸브의 수명예측을 위한 핵심요소인 모수 도출 및 제안을 위하여, 최근 널리 사용되고 있는 플러그인형 공기압 매니폴드 밸브의 척도모수 및 $B_{10}$ 수명값을 완전데이터 수명관측 방법으로 측정하였으며, 수명분포 특성을 확인하기 위하여 상관계수값을 이용한 분포 적합성 검토와 주요성능 결정항목인 동적응답과 누설이 수명에 따라 열화되는 특성을 분석한 결과를 제시한다.

• Molecular & Cellular Toxicology
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• 제1권4호
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• pp.275-280
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• 2005

Carbon tetrachloride ($CCl_4$) is well known hepatotoxicant. Its overdose cause severe centrilobular hepatic necrosis in human and experimental animals. We administered $CCl_{4}$ at low (0.2 mL/kg p.o.) and high (2 mL/kg p.o.) doses to mice. Mice were sacrificed at 24 h after administration. We evaluated liver toxicity by serum AST and ALT level and by microscopic observation. Using cDNA chip, we conducted gene expression analysis in liver. Mean serum activities of the hepatocellular leakage enzymes, ALT and AST, were significantly increased compare to control, respectively, in the low and high dose groups. H&E evaluation of stained liver sections revealed $CCl_{4}-related$ histopathological findings in mice. Moderate centrilobular hepatocellular necrosis was present in all $CCl_{4}$ treated mice. We found that gene expression pattern was very similar between low and high dose group. However, some stress related genes were differently expressed. These results could be a molecular signature for the degree of liver injury. Our data suggest that the degree of severity could be figure out by gene expression profiling.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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• pp.731-763
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• 2017

In Underwater Linear Sensor Networks (UW-LSN) routing process, nodes without proper address make it difficult to determine relative sensor details specially the position of the node. In addition, it effects to determine the exact leakage position with minimized delay for long range underwater pipeline monitoring. Several studies have been made to overcome the mentioned issues. However, little attention has been given to minimize communication delay using dynamic addressing schemes. This paper presents the novel solution called Hop-by-Hop Dynamic Addressing based Routing Protocol for Pipeline Monitoring (H2-DARP-PM) to deal with nodes addressing and communication delay. H2-DARP-PM assigns a dynamic hop address to every participating node in an efficient manner. Dynamic addressing mechanism employed by H2-DARP-PM differentiates the heterogeneous types of sensor nodes thereby helping to control the traffic flows between the nodes. The proposed dynamic addressing mechanism provides support in the selection of an appropriate next hop neighbour. Simulation results and analytical model illustrate that H2-DARP-PM addressing support distribution of topology into different ranges of heterogeneous sensors and sinks to mitigate the higher delay issue. One of the distinguishing characteristics of H2-DARP-PM has the capability to operate with a fewer number of sensor nodes deployed for long-range underwater pipeline monitoring.

• 융합보안논문지
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• 제20권3호
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• pp.89-97
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• 2020

산업기술 보안 이슈는 대내외적으로 급격한 변화를 겪고 있다. 미국 등 선진국은 글로벌 가치사슬 및 해외자본 이동과 갈등을 빚으면서도 자국의 핵심 기술 보호를 위한 대응전략을 수립하고 있으며, 국내 또한 중장기 산업경쟁력 속에서 산업안보이슈를 접근하고 있다. 본 연구에서는 국내 산업보안 관련 이해관계자들을 대상으로 산업보안 생태계 정책인식 조사를 통해 주요 이슈를 도출하였다. 조사결과, 이해관계자 모두 산업보안의 중요성에 대해 인식하나 아직까지 국가전체 보안관리 역량은 낮다고 인식하고 있으며, 국가핵심기술은 국가에서 보다 책임을 지고 관리할 필요성이 있음을 제기하였다. 3라운드에 걸친 종합 델파이 조사를 기반으로 '산업보안 컨트롤타워 중심 시스템 체계화', '보안전문기업 기술력 강화 및 보안인력 양성', '인력 및 자본을 통한 기술유출 방지제도 개선', '연구개발 과정에서의 연구보안 및 선제적 기술보호 강화'를 정책개선 과제로 제시하였다. 본 연구가 산업보안 현장의 수요를 반영한 증거 기반 연구로서 관련 정책수립의 기초가 될 수 있기를 기대한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권10호
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• pp.438-442
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• 2005

Si nanocrystal (Si NC) memory device has several advantages such as better retention, lower operating voltage, reduced punch-through and consequently a smaller cell area, suppressed leakage current. However, the physical and electrical reasons for this behavior are not completely understood but could be related to interface states of Si NCs. In order to find out this effect, we characterized electrical properties of Si NCs embedded in a SiO$_{2}$ layer by scanning probe microscopy (SPM). The Si NCs were generated by the laser ablation method with compressed Si powder and followed by a sharpening oxidation. In this step Si NCs are capped with a thin oxide layer with the thickness of 1$\~$2 nm for isolation and the size control. The size of 51 NCs is in the range of 10$\~$50 m and the density around 10$^{11}$/cm$^{2}$ It also affects the interface states of Si NCs, resulting in the change of electrical properties. Using a conducting tip, the charge was injected directly into each Si NC, and the image contrast change and dC/dV curve shift due to the trapped charges were monitored. The results were compared with C-V characteristics of the conventional MOS capacitor structure.