• Current Photovoltaic Research
• /
• v.3 no.3
• /
• pp.85-90
• /
• 2015

Two-step processes for preparing $Cu(In,Ga)Se_2$ absorber layers consist of precursor layer formation and subsequent annealing in a Se-containing atmosphere. Among the various deposition methods for precursor layer, the nonvacuum (wet) processes have been spotlighted as alternatives to vacuum-based methods due to their potential to realize low-cost, scalable PV devices. However, due to its porous nature, the precursor layer deposited on Mo substrate by nonvacuum methods often suffers from thick $MoSe_2$ formation during selenization under a high Se vapor pressure. On the contrary, selenization under a low Se pressure to avoid $MoSe_2$ formation typically leads to low crystal quality of absorber films. Although TiN has been reported as a diffusion barrier against Se, the additional sputtering to deposit TiN layer may induce the complexity of fabrication process and nullify the advantages of nonvacuum deposition of absorber film. In this work, Mo oxide layers via thermal oxidation of Mo substrate have been explored as an alternative diffusion barrier. The morphology and phase evolution was examined as a function of oxidation temperature. The resulting Mo/Mo oxides double layers were employed as a back contact electrode for $CuInSe_2$ solar cells and were found to effectively suppress the formation of $MoSe_2$ layer.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.8
• /
• pp.5213-5218
• /
• 2014

Organic memory devices were made using the plasma polymerization method. The memory device consisted of ppMMA(plasma polymerization MMA) thin films as the tunneling and insulating layer, and a Au thin film as the memory layer, which was deposited by thermal evaporation. The organic memory operation theory was developed according to the charging and discharging characteristics of floating gate type memory, which would be measured by the hysteresis voltage and memory voltage with the gate voltage values. The I-V characteristics of the fabricated memory device showed a hysteresis voltage of 26 [V] at 60 ~ -60 [V] double sweep measuring conditions. The programming voltage was applied to the gate electrode in accordance with the result of this theory. A programming voltage of 60[V] equated to a memory voltage of 13[V], and 80[V] equated to a memory voltage of 18[V]. The memory voltage of approximately 40 [%]increased with increasing programming voltage. The charge memory layer charging or discharging according to the theory of the memory was verified experimentally.

• Journal of Biosystems Engineering
• /
• v.39 no.1
• /
• pp.21-33
• /
• 2014

Background: Significant technological development and changes happened in the tractor industries. Contrariwise, the test procedures of the major standard development organizations (SDO's) remained unchanged or with a little modification over the years, demanding new tractor test standards or improvement of existing ones for tractor performance, safety, and comfort. Purpose: This study focuses on reviewing the research trends regarding performance, safety and comfort evaluation of agricultural tractors. Based on this review, few recommendations were proposed to revise or improve the current test standards. Review: Tractor power take-off power test using the DC electric dynamometer reduced human error in the testing process and increased the accuracy of the test results. GPS signals were used to determine acceleration and converted into torque. High capacity double extended octagonal ring dynamometer has been designed to measure drawbar forces. Numerical optimization methodology has been used to design three-point hitch. Numerous technologies, driving strategies, and transmission characteristics are being considered for reducing emissions of gaseous and particulate pollutants. Engine emission control technology standards need to be revised to meet the exhaust regulations for agricultural tractors. Finite Element Analysis (FEA) program has been used to design Roll-Over Protective Structures (ROPS). Program and methodology has been presented for testing tractor brake systems. Whole-body vibration emission levels have been found to be very dependent upon the nature of field operation performed, and the test track techniques required development/adaptation to improve their suitability during standardized assessment. Emphasizes should be given to improve visibility and thermal environment inside the cab for tractor operator. Tractors need to be evaluated under electromagnetic compatibility test conditions due to large growing of electronic devices. Research trends reviewed in this paper can be considered for possible revision or improvement of tractor performance, safety, and comfort test standards.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.1
• /
• pp.69-78
• /
• 2001

This paper presents the design and FPGA implementation of a FLEX PSP(Protocol Signal Processor) for the portable high speed paging system. In this approach, two algorithms are newly proposed for implementing the PSP which provides capabilities of the maximum 6,400bps at speed, high-channel throughput, real time error correction and an effective frame search function. One is an accurate symbol synchronization algorithm which is applied for synchronizing the interleaved 4-level bit symbols which are received at input stage of A/D converter, and the other is a modified fast decoding algorithm which is provided for realizing double error correction of (31,21)BCH signal. The PSP is composed of six functional modules, and each module is modelled in VHDL(VHSIC Hardware Description Language). Both functional simulation and logic synthesis have performed for the proposed PSP through the use of Synopsys$^{TM}$ tools on a Axil-320 Workstation, and where Altera 10K libraries are used for logic synthesis. From logic synthesis, we can see that the number of gates is about 2,631. For FPGA implementation, timing simulation is performed by using Altera MAX+ PLUS II, and its results will be also given. The PSP which is implemented in 6 FPGA devices on a PCB has been verified by means of Logic Analyzer.r.

• Journal of the Korean Vacuum Society
• /
• v.15 no.6
• /
• pp.637-641
• /
• 2006

We present the DC and RF characteristics of 100 nm gate length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistors (MHEMTs). We fabricated the T-gate with 100 nm foot print by using a positive resist ZEP520/P (MMA-MAA)/PMMA trilayer by double exposure method. The fabricated 100 nm MHEMT with a $70\;{\mu}m$ unit gate width and two fingers were characterized through do and rf measurements. The maximum drain current density of 465 mA/mm and extrinsic transconductance $(g_m)$ of 844 mS/mm were obtained with our devices. From rf measurements, we obtained the current gain cut-off frequency $(f_T)$ of 192 GHz, and maximum oscillation frequency $(f_{max})$ 310 GHz.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.11
• /
• pp.71-78
• /
• 2019

Most 3D displays that are currently in the market adopt the binocular disparity method creating a different image for the left and right eye for a 3 dimensional effect. However, commercialized 3D image output devices lack in performance making it uncomfortable for the viewer and restrict the viewer to certain positions. In this paper, we propose a single-cell polarized lens type stereoscopic system which has a smaller viewing angle and reduced crosstalk, with improved light penetration compared to existing double-cell structures; and analyzed the single-cell polarized lens type stereoscopic system properties, and conducted an effect analysis of performance improvement compared to the dual-cell type. Results showed that the single-cell type had a 25% improved performance, and the 3D crosstalk index which is an important index for quality characteristics of stereoscopic systems, increased over about 37%, compared to the dual-cell type.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.5
• /
• pp.825-834
• /
• 2021

With the development of various devices and Internet platforms, production and demand for content are increasing rapidly. However, effective response to exponentially increasing data usage is difficult in current TCP/IP schemes. As a result, with the emergence of an alternative called CCN, data can be transmitted and received from the host-centered to the content-oriented, and large-capacity content can be handled with more mitigated network resources. In this paper, we will address intermediate node mobility, which is one of the areas studied in CCN. In CCN, real-time services are a very important factor for information providers as well as requestors. However, when a node departure situation occurs, packet transmission and transmission speed decreases. Therefore, to ensure these numbers, even if the intermediate node deviates using a dual path, it provides a complete QoS (Quality of Service) using an alternative path.

• Progress in Medical Physics
• /
• v.29 no.4
• /
• pp.123-136
• /
• 2018

The complex dose distribution and dose transfer characteristics of intensity-modulated radiotherapy increase the importance of precise beam data measurement and review in the acceptance inspection and preparation stages. In this study, we propose a process map for the introduction and installation of high-precision radiotherapy devices and present items and guidelines for risk management at the acceptance test procedure (ATP) and commissioning stages. Based on the ATP of the Varian and Elekta linear accelerators, the ATP items were checked step by step and compared with the quality assurance (QA) test items of the AAPM TG-142 described for the medical accelerator QA. Based on the commissioning procedure, dose quality control protocol, and mechanical quality control protocol presented at international conferences, step-by-step check items and commissioning guidelines were derived. The risk management items at each stage were (1) 21 ionization chamber performance test items and 9 electrometer, cable, and connector inspection items related to the dosimetry system; (2) 34 mechanical and dose-checking items during ATP, 22 multileaf collimator (MLC) items, and 36 imaging system items; and (3) 28 items in the measurement preparation stage and 32 items in the measurement stage after commissioning. Because the items presented in these guidelines are limited in terms of special treatment, items and practitioners can be modified to reflect the clinical needs of the institution. During the system installation, it is recommended that at least two clinically qualified medical physicists (CQMP) perform a double check in compliance with the two-person rule. We expect that this result will be useful as a radiation safety management tool that can prevent radiation accidents at each stage during the introduction of radiotherapy and the system installation process.

• Korean Chemical Engineering Research
• /
• v.57 no.3
• /
• pp.321-330
• /
• 2019

With the rapid development trend in multidisciplinary science and convergence technology, digital data storages have been necessary in order to accumulate a huge amount of information with high security. The possibility that biological DNA code system can offer encoding and decoding information has been illustrated by many researchers. In this review, we summarized current issue of info-convergence nanohybrid system, so-called infohybrid. DNA-inorganic nanohybrid materials and devices to achieve DNA-based molecular information system are presented. The possible applications focusing on tracking-and-traceability management, authenticity verification, and nano-forensics are also reviewed with four steps of encoding, encrypting, decrypting and decoding. We also highlighted the potential of smart code system with Nano-Bio-Info-Cogno (NBIC) convergence technology through the recently published case study of Avatar DNA nanohybrid system with smart phone.

• Current Optics and Photonics
• /
• v.5 no.2
• /
• pp.147-154
• /
• 2021

Microfluidic chip technology is a research focus in biology, chemistry, and medicine, for example. However, microfluidic chips are rarely applied in imaging, especially in ghost imaging. Thus in this work we propose a ghost-imaging system, in which we deploy a novel microfluidic chip modulator (MCM) constructed of double-layer zigzag micro pipelines. While in traditional situations a spatial light modulator (SLM) and supporting computers are required, we can get rid of active modulation devices and computers with this proposed scheme. The corresponding simulation analysis verifies good feasibility of the scheme, which can ensure the quality of data transmission and achieve convenient, fast ghost imaging passively.