Band offsets and optical conduction in the CdSe/GaSe interface

T.S. Kayed,A.F. Qasrawi,Khaled A. Elsayed 한국물리학회 2016 Current Applied Physics Vol.16 No.7

In this work, the design and characterization of CdSe/GaSe heterojunction is considered. The CdSe/GaSe thin film interface was prepared by the physical vapor deposition technique. Systematic structural and optical analysis were performed to explore the crystalline nature, the optical band gaps, the conduction and valence band offsets, the dielectric spectra, and the frequency dependent optical conductivity at terahertz frequencies. The X-ray diffraction analysis revealed a polycrystalline interface that is mostly dominated by the hexagonal CdSe oriented in the (002) direction. It was also found that the CdSe/GaSe interface exhibits conduction and valence band offsets of 1.35 and 1.23/1.14 eV, respectively. The dielectric spectra displayed two dielectric resonance peaks at 530 and 445 THz. Moreover, the computational fittings of the optical conductivity of the interface revealed a free carrier scattering time of 0.41 (fs) for a free carrier density of 7.0 1018 (cm3). The field effect mobility for the CdSe/GaSe interface was found to be 5.22 (cm2/Vs). The remarkable features of this device having large band offsets and qualitative optical conduction dominated by a scattering time in the order of femtoseconds in addition to the dielectric property nominate the device to be used in optoelectronic technology.

Health Care Optimization by Maximizing the Air-Ambulance Operation Time

Melhim, Loai Kayed B. International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.2

Employing the available technologies and utilizing the advanced means to improve the level of health care provided to citizens in their various locations. Citizens have the right to get a proper health care services despite the location of their residency or the distance from the health care delivery centers, a goal that can be achieved by utilizing air ambulance systems. In such systems, aircrafts and their life spans are the essential component, the flight duration of the aircraft during its life span is determined by the maintenance schedule. This research, enhances the air ambulance systems by presenting a proposal that maximizes the aircraft flight duration during its life span. The enhancement will be reached by developing a set of algorithms that handles the aircraft maintenance problem. The objective of these algorithms is to minimize the maximum completion time of all maintenance tasks, thus increasing the aircraft operation time. Practical experiments performed to these algorithms showed the ability of these algorithms to achieve the desired goal. The developed algorithms will manage the maintenance scheduling problem to maximize the uptime of the air ambulance which can be achieved by maximizing the minimum life of spare parts. The developed algorithms showed good performance measures during experimental tests. The 3LSL algorithm showed a higher performance compared to other algorithms during all performed experiments.

Characterization of Au/As2Se3/MoO3/Ag hybrid devices designed for dual optoelectronic applications

T.S. Kayed,A.F. Qasrawi 한국물리학회 2020 Current Applied Physics Vol.20 No.1

In this work, hybrid devices composed of n As2Se3/p MoO3 encapsulated between two Schottky shoulders (Au/n-As2Se3, Ag/MoO3) are prepared and characterized. While the structural analyses proofed the preferred growth of monoclinic MoO3 onto amorphous layers of As2Se3, the spectroscopic ellipsometry analysis revealed the high frequency dielectric constants, the effective mass and the negative pseudodielectric constant values. Electrically, the hybrid device displayed both tunneling and standard diode characteristics. As passive mode devices, the capacitance-voltage characteristics displayed the accumulation-depletion -inversion modes in the device. Furthermore, the conductivity spectral analysis has shown that the current conduction is dominated by the quantum mechanical tunneling and correlated barriers hoping mechanisms. The amplitude of the reflection coefficient and the return loss spectral analyses indicated that the hybrid devices are band stop filters in addition to it is usability as nonlinear optical interfaces, CMOS device and tunneling diodes.

Steganography: A Flexible Embedded Randomization Technique

Khaled H. Abuhmaidan,Ahmad K. Kayed,Maryam Alrisia 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.1

With the expansion of digital communication networks, a considerable number of randomization techniques have been invented and implemented to enhance the different data transmission algorithms' levels of security. Steganography is among the data transmissions techniques used to hide secret data. Nowadays, several randomization techniques have been used in steganography to elevate the security of transmitted data. Unfortunately, the majority of these techniques lack some simplicity, efficiency, and flexibility, in addition to other limitations. This research presents a new randomization technique called Rand-Stego. Rand-Stego could be applied/practiced over any steganography technique. It provides simplicity and efficiency and elevates the security level. Examples of implementing the proposed technique on some steganography algorithms will be explored. The proposed and current techniques will be compared. The obtained results show Rand-Stego's superiority in terms of efficiency and flexibility when compared to the current techniques.

Enhancing Data Protection in Digital Communication: A Novel Method of Combining Steganography and Encryption

Khaled H. Abuhmaidan,Marwan A. Al-Share,Abdallah M. Abualkishik,Ahmad Kayed 한국인터넷정보학회 2024 KSII Transactions on Internet and Information Syst Vol.18 No.6

In today's highly digitized landscape, securing digital communication is paramount due to threats like hacking, unauthorized data access, and network policy violations. The response to these challenges has been the development of cryptography applications, though many existing techniques face issues of complexity, efficiency, and limitations. Notably, sophisticated intruders can easily discern encrypted data during transmission, casting doubt on overall security. In contrast to encryption, steganography offers the unique advantage of concealing data without easy detection, although it, too, grapples with challenges. The primary hurdles in image steganography revolve around the quality and payload capacity of the cover image, which are persistently compromised. This article introduces a pioneering approach that integrates image steganography and encryption, presenting the BitPatternStego method. This novel technique addresses prevalent issues in image steganography, such as stego-image quality and payload, by concealing secret data within image pixels with identical bit patterns as their characters. Consequently, concerns regarding the quality and payload capacity of steganographic images become obsolete. Moreover, the BitPatternStego method boasts the capability to generate millions of keys for the same secret message, offering a robust and versatile solution to the evolving landscape of digital security challenges.

ERK1/2 Activation Mediates Aβ Oligomer-induced Neurotoxicity via Caspase-3 Activation and Tau Cleavage in Rat Organotypic Hippocampal Slice Cultures

Chong, Young Hae,Shin, Yoo Jeong,Lee, Eun Ok,Kayed, Rakez,Glabe, Charles G.,Tenner, Andrea J. American Society for Biochemistry and Molecular Bi 2006 The Journal of biological chemistry Vol.281 No.29

Caspase-cleaved tau exhibits rapid memory impairment associated with tau oligomers in a transgenic mouse model

Kim, Y.,Choi, H.,Lee, W.,Park, H.,Kam, T.I.,Hong, S.h.,Nah, J.,Jung, S.,Shin, B.,Lee, H.,Choi, T.Y.,Choo, H.,Kim, K.K.,Choi, S.Y.,Kayed, R.,Jung, Y.K. Blackwell Science ; Academic Press 2016 Neurobiology of disease Vol.87 No.-

<P>In neurodegenerative diseases like AD, tau forms neurofibrillary tangles, composed of tau protein. In the AD brain, activated caspases cleave tau at the 421th Asp, generating a caspase-cleaved form of tau, TauC3. Although TauC3 is known to assemble rapidly into filaments in vitro, a role of TauC3 in vivo remains unclear. Here, we generated a transgenic mouse expressing human TauC3 using a neuron-specific promoter. In this mouse, we found that human TauC3 was expressed in the hippocampus and cortex. Interestingly, TauC3 mice showed drastic learning and spatial memory deficits and reduced synaptic density at a young age (2-3 months). Notably, tau oligomers as well as tau aggregates were found in TauC3 mice showing memory deficits. Further, i.p. or i.c.v. injection with methylene blue or Congo red, inhibitors of tau aggregation in vitro, and i.p. injection with rapamycin significantly reduced the amounts of tau oligomers in the hippocampus, rescued spine density, and attenuated memory impairment in TauC3 mice. Together, these results suggest that TauC3 facilitates early memory impairment in trans genic mice accompanied with tau oligomer formation, providing insight into the role of TauC3 in the AD pathogenesis associated with tau oligomers and a useful AD model to test drug candidates. (C) 2015 Elsevier Inc. All rights reserved.</P>

分析模型間의 比較檢定에 관한 經路硏究 : 國防費 支出 函數 推定을 中心으로 Focus on the Inference of Defense Expenditure Function

韓啓燮 東亞大學校 大學院 1992 大學院論文集 Vol.17 No.-

This paper shows how we can construct the most suitable models which make solve functional problems correctly in practical human societies. There are many kinds of methods to control all variables concerned in the functional relations and produce fruitful results sometime later. But most of cases in the problems we often miss the processes or the procedures in surveying situations and directing the correct variables. In the article we can only find fitted variables in applying to the practical functional problems which include time-series data of Korean Defense Expenditures for 30 years. In the paper we tested some models by the variables filtered properly for the purposes. After testing all possible hypotheses on these analytical inference we checked the best variables Which can represent the situational inferences we checked the best variables which can represent the situational defense expenditures according to the time differential factors. The approach adopted in this tests is to discuss a class of models which are sufficiently flexible to describe practical situations for the defense expenditures paid for the periods in Korea. The process of model building, which is discussed in the paper is concerned with relating such a class of statistical models to the data at hand and involves much more than model fitting in the functional defense expenditures. Thus, identification techniques, designed to suggest what paticular kind of might be worth considering are developed first and make use of the autocorrelation and partial autocorrelation functions for military expenses. The time series data are supplied to the models on Korean Defense Expenditures for 30 years from the year of 1961 to 1990. The procedures of the data processes are fitted all situations by each model using expenditure function if it is proper or not. Usually Korean defense expenditure has been paid almost 5% - 6% of its GNP annually for those years. As we know very well, of course, the circumstances of the peninsular are quite different from those Western countries in their military balance, politics, socio-economies and etc. But we have to find out the proper way how Korean people could live safely and comfortably in spite of paying such huge defense expenses for the long time. So we need to compare the situations with the U.S model which expreses the differnt conditions in processing the variables and in fitting methods. After all we can select comparable models for Korean situations and apply that patterns to the functional equations for the purpose. As a result we can conclude as follows : 1. The relation between the Korean economic growth and its defense expenditure is exclusive each other for the time. 2. The GNP and Defense Expenditure in Korea is proportionally developed until now. 3. The relations among the foreign debts, imports and defense expenditires of the country are deeply positive independently. 4. The Korean defense expenditure is quite intangibel to the private consumption expendirues and the government consumption expenditures. 5. Therefore, taking out right variable elements for applying to the proper models, it needs to filter the functional processes more sufficient statistical steps and its adequate procedures for solving Korean defense expenditure problems in the future.

中小製造業의 情報시스템 構築 方案 硏究

韓啓燮 동아대학교 경영대학 1994 經營硏究 Vol.- No.8

The information and communication technology makes all the people and their organizations change into information society. Especially all the firms need urgently its information systems to survive themselves in the competitive business society. The necessity of constructing well-applicable Information Systems is growing day by day to success in the fields. This paper provides an effective method to construct information systems which can be used very economical but powerful in small and medium manufacturing companies. Even though some advanced and big business are already operating their own appropriate information systems so as to get their remarkable productivity nowdays. The rest of those small firms are still trying to find out some acceptable systems fitting their own business in very poor situations. So this paper shows the situations of information systems in the small and medium manufacturing companies of the days. And then the directions for constructing information systems promoting those firms growing by the systems. This paper analized the real status of general management situations showed the solving procedures and methods to construct proper information systems on those firms. As a result, this study introduces somehow low cost, efficient, convinient flexible and very useful applying information systems with easier ways.

부채비율이 주식수익률과 주가순자산 비율에 미치는 영향에 관한 연구 : 외환위기 부채비율 200%를 중심으로 Empirical Evidence

이계원 한국세무회계학회 2004 세무회계연구 Vol.15 No.-

본 연구는 자본구조(부채비율)가 기업가치의 대리변수라 할 수 있는 초과수익률과 주가순자산비율에 영향을 미치는지의 여부를 검증한다. 특히, 외환위기 이후 IMF의 요구에 따른 부채비율 200%이하라는 목표를 달성한 기업들에서 자본구조와 기업가치간에 어떤 유의적인 관련성이 있는지를 살펴보고자 한다. 즉, 부채비율 200%를 최적자본구조의 기준점이 될 수 있을 것인지를 살피기 위해, 외환위기 이전 2년과 이후 3년 동안인 1996년 1월부터 2001년 12월까지를 표본기간으로 선정하고, 표본기업은 상장기업 중 결산일이 12월 31일인 제조업을 대상으로 536개 기업(5년간 누적 기업수임)을 선정하였다. 실증분석 결과, 외환위기 이후 정부가 정책목표로 설정한 부채비율 200%이하 의무달성 5대 재벌기업들은 물론, 재벌기업과 비재벌기업을 분류하여 분석한 결과에서도 자본구조가 기업가치에 유의적인 영향을 미치지 않는 것으로 나타났다. 결국 부채비율 200%가 기업가치를 극대화하기 위한 최적자본구조로서 의미를 지니지 못하였다고 판단된다. 이는 비록 IMF의 요구에 따른 정부의 부채비율 200%이하 정책으로서 단기적으로는 기업의 위험축소라는 나름대로의 긍정적인면이 있지만, 부채비율 축소로 인하여 기업가치가 달라지지 않았다면 기업으로 하여금 중·장기적인 새로운 투자를 할 수 있는 기회를 가지지 못하게 하는데 일조를 한 것으로 보인다.