Earticle

In the present numerical research, develop a high-efficiency fan model to improve the performance of the cooling fan, which accounts for a lot of weight in the efficiency of the cooling tower. For this purpose, analyze the shape of the existing cooling fan model and use CFD. The main variable set in the analysis of the cooling fan model is the pitch angle, and the range of the pitch angle was investigated in the range of 0° to 20°. The purpose of this research is to select the optimum driving condition by using CFD for setting the pitch angle that depends on the existing experience. The research results showed the best results when the pitch angle range was 15°~18°.

The Alkali-Metal Thermal to Electric Converter (AMTEC) can be used as a next-generation power generation technology related with a large thermal energy storage. In particular, this technology is expected for the higher efficiency by a cascade power generation with the thermoelectric generator(TEG), and the temperature distribution becomes a very important design parameter in this case. In this study, the temperature distribution of the AMTEC unit was analyzed through CFD analysis, and design points were discussed based on the results.

A low-profile high efficiency transmitarray antenna (TA) using an optimized phase compensation surface (PCS) and PEC sidewalls is proposed in this paper. Generally, TAs are composed of a source antenna and a planar PCS, and the PCS makes the phase of transmitted wave through the PCS be in-phase, resulting in a highly directive beam. The unit cells of a PCS cannot have a 100% transmittance at all transmission phases. Since there may be combinations of PCS that make various in-phases, the transmit efficiency of the TA can be improved. Also, the four PEC sidewalls are employed to maximize the amount of power reaching the PCS from the source antenna. As a result, the 100% spillover efficiency is achieved without diminishing taper efficiency. To verify its feasibility, the square TA was designed and measured at 5.8GHz and a high aperture efficiency of 54% was obtained through the above design methodology.

Feed cost is the main factor affecting the economic benefits of pig industry. Improving the feed efficiency (FE) can reduce the feed cost and improve the economic benefits of pig breeding enterprises. Liver is a complex metabolic organ which affects the distribution of nutrients and regulates the efficiency of energy conversion from nutrients to muscle or fat, thereby affecting feed efficiency. MicroRNAs (miRNAs) are small non-coding RNAs that can regulate feed efficiency through the modulation of gene expression at the post-transcriptional level. In this study, we analyzed miRNA profiling of liver tissues in High-FE and Low-FE pigs for the purpose of identifying key miRNAs related to feed efficiency. A total 212~221 annotated porcine miRNAs and 136~281 novel miRNAs were identified in the pig liver. Among them, 188 annotated miRNAs were co-expressed in High-FE and Low-FE pigs. The 14 miRNAs were significantly differentially expressed (DE) in the livers of high-FE pigs and low-FE pigs, of which 5 were downregulated and 9 were upregulated. Kyoto Encyclopedia of Genes and Genomes analysis of liver DE miRNAs in high-FE pigs and low-FE pigs indicated that the target genes of DE miRNAs were significantly enriched in insulin signaling pathway, Gonadotropin- releasing hormone signaling pathway, and mammalian target of rapamycin signaling pathway. To verify the reliability of sequencing results, 5 DE miRNAs were randomly selected for quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The qRT-PCR results of miRNAs were confirmed to be consistent with sequencing data. DE miRNA data indicated that liver-specific miRNAs synergistically acted with mRNAs to improve feed efficiency. The liver miRNAs expression analysis revealed the metabolic pathways by which the liver miRNAs regulate pig feed efficiency.

Non-contact power supply (NCPS), as a clean and safe energy supply concept has been applying wildly. Comparing with the conventional transformer the non-contact transformer has a large air gap between the long primary winding and the secondary winding. Due to it, the non-contact transformer has increased leakage inductance and reduced magnetizing inductance. So the high frequency series resonant converter has been widly used on the non-contact power supply system for transferring the primary power to the secondary one, from what a high influence voltage can be gained on the secondry coil even though the large air gap exists. However, it still has the disadvantages of the load sensitive voltage gain characteristics when load is changing. In this paper, we propose a fuzzy logic controller to adjust the frequency of the inverter to track the resonat which is changing when the load is change.

전 세계적으로 지능형 교통시스템(ITS)의 도입이 가속화됨에 따라, 안전하고 효율적인 차량-사물 간 통신(V2X)을 보장하는 것은 핵심적인 요구사항이 되었다. RSA 및 ECC와 같은 기존의 암호화 기법은 강력한 보안을 제공하지만, 현대 차량의 제약된 환경에는 과도한 계산 부하를 초래한다. 본 논문에서는 잉여 수 시스 템(RNS)과 몽고메리 모듈러 곱셈을 결합한 새로운 암호화 프레임워크를 제안한다. 이 프레임워크는 우수한 성 능, 낮은 에너지 소비, 강력한 보안성을 동시에 제공한다. 자율주행은 빠른 판단이 요구되므로 효율성을 높이 는 것은 안전과 직결되며, 매우 중요한 요소이다. 시뮬레이션과 비교 분석을 통해 본 프레임워크가 암호화 시 간과 계산 부하를 획기적으로 줄이며, 실시간 ITS 응용에 적합한 실용적인 솔루션임을 입증한다.

As the deployment of Intelligent Transportation Systems (ITS) accelerates globally, ensuring secure and efficient Vehicle-to-Everything (V2X) communication becomes a fundamental requirement. Traditional cryptographic methods such as RSA and ECC offer strong security but impose computational burdens that are ill-suited to the constrained environments of modern vehicles. In this paper, we propose a novel cryptographic framework that integrates the Residue Number System (RNS) with Montgomery modular multiplication to deliver enhanced performance, low energy consumption, and strong security guarantees. Since autonomous driving requires rapid decision-making, improving computational efficiency is directly tied to safety and is therefore a critical factor. Through simulation and comparative analysis, we demonstrate that our framework significantly reduces encryption time and computational overhead, making it a practical solution for real-time ITS applications.

Background: Gamma emission tomography (GET) is one of the most reliable methods for detection of partial-defects within spent nuclear fuel (SNF). In our previous study, we developed and proposed the scintillation crystal-based GET instrument named Yonsei single-photon emission computed tomography (YSECT). However, this conventional YSECT instrument has consequential limitations related to the low inspection accuracy in the central region, which fact is due to the high density of nuclear fuel rods. This study aimed to derive, as proposed in this paper and using Monte Carlo simulation, a multisensor-based YSECT for enhancement of partialdefect detection accuracy. Materials and Methods: The gamma-ray energy spectra for gadolinium aluminum gallium garnet (GAGG), CsI(Tl), CdWO4, and PbWO4 were obtained to determine the appropriate material for image quality improvement in the central region. The shapes of the spectra and the detection efficiencies were compared among the scintillation crystal materials. The tomographic images were acquired with both conventional YSECT and the newly proposed YSECT, and their quality was compared based on the signal-to-noise ratio (SNR). Results and Discussion: CdWO4 was found to have a detection efficiency twice as high as that of GAGG, owing to its high-density despite poor light yield. Based on these results, the optimal scintillation crystal material for enhancement of detection efficiency for high-energy (>662 keV) gamma rays was determined to be CdWO4. In accordance with the optimization study, the SNR of the CdWO4 image was calculated as 7.95, which was higher than that of the GAGG image by a factor of 2. Furthermore, the SNR of the synthesis image was determined to be 9.85, which was higher than that of the single-sensor–based YSECT image by a factor of 1.59. Conclusion: Based on these results, we believe that the multisensor-based YSECT can enhance inspection accuracy for partial defects arising in pressurized water reactor-type SNF. In further studies, the effect and influence of neutrons will be evaluated and noise-reduction methods will be developed.

IEEE 802.11ax High Efficiency WLAN(HEW) 기술은 IEEE 802.11ac 다음으로 주목 받고 있는 무선랜 기술로 현재 2019년 완성을 목표로 표준화가 진행되고 있으며 올해 5월에 TG로 구성되었다. 지금까지 개발된 무선랜 기술들은 주위의 다른 무선랜망의 영향을 크게 고려하지 않고 단순히 전송속도를 높이려는 목적으로 개발되어 왔으나, 이러한 단순한 목적에서 벗어나 무선랜 기기들로 밀집된 환경에서 타기기들의 영향을 덜 받으며 실제 사용자가 체감하는 전송 속도를 증진시키기 위한 무선랜 기술을 개발하는 것을 목표로 하고 있다. 본 고에서는 현재 진 행중인 IEEE 802.11ax 기술 표준의 표준화 동향에 대해서 알아보고 향후 기술 발전 방향에 대 해 알아본다.

As post-harvest processes of onions are carried by a 20 kg-net package which results in high-cost and lowefficiency, especially, the insufficient drying and physical damage of onions after harvesting leads to a huge second loss in storage, we had developed a low-cost, high-efficiency post-harvest bulk handling machinery system by collecting onions on a farm using ton-bags, drying with forced air circulation, and sorting/packaging. The post-harvest bulk handling machinery system consisted of 6 devices, and this study designed an automatic feed hopper with a feeding rate control device, an inclined belt conveyor with a two-step chute, and an automatic pallet unloading device for feeding onions into the sorting/packing line. This study also analyzed the performance and control of the total system. The device had 1-ton handling capacity, but the operational condition was set to increase the capacity. The three-step filling method of pallet by the velocity control of the inclined belt conveyor was applied in the post-harvest bulk handling machinery system for the prevention of physical damage. If one worker was set to operate the total system, the time required to complete one palletized load was approximately 5 minutes and 5 seconds. The calculated daily handling capacity was approximately 94 tons, when the daily actual working time was 8 hours. When the developed system was applied to the managerial size of 2,000 ton, the processing cost per ton of the system was decreased by 19.5%, compared with the existing 20 kg-net package-based handling. The developed post-harvest bulk handling machinery system would be a good substitute for the rapid decline and aging of rural labor.

This paper describes study of the converter topologies for a low-cost, high-efficiency switched reluctance motor(hereafter abbreviated as SRM) drive. The considered converter employs two-switch split AC supply configuration. The converter preserves a single switch per phase as well as a single phase-leg rectifier circuit realizing the fewest component count to achieve a highly cost effective solution for two-phase SRM drive. Comparative study between the considered converter and other converters are provided. Analysis of the modes of operation and mathematical modeling are also provided. Analysis and simulation results are provided to validate the converter. The considered split AC converter can be a strong candidate for low-cost applications such as power tools, fans, and small appliances where both cost and efficiency are most valued.

Using aeration reactor of high efficiency pure oxygen to remove the high concentration wastewater generated by the solution separated from food waste, the results got from a pilot test are summarized as follows. 1. The process composition to remove the high concentrated organic matter and the nitrogen of wastewater is the facilities to control the primary high liquid separation and the second biological control process is composed of the anoxic tank and the high pure oxygen aeration reactor and the separation membrane tank, and the advanced control is composed of the ozone and activated carbon treatment facility. 2. As the average concentration of 200,000 mg/L is separated into high liquid to mix with excess sludge, the water separated from high liquid is able to get the average of 32,000 mg/L, and when the load of about 20 kgCODCr/m3·d removes by the reactor of the pure oxygen aeration with high efficiency, it has been removed over the 98.7% to an outflow with average 422 mg/L. 3. As the BOD flows into the raw wastewater with 90,000 mg/L, an average concentration shows 32,000 mg/L after a primary high liquid separation and is able to get the effluent water under below 10 mg/L to remove 99.9% by the aeration reactor of high efficiency pure oxygen. 4. T-N represents average 1,520 mg/L when the raw wastewater with about 3,500 mg/L is separated from high liquid, and it is removed to the efficiency of 94.1% or more when it is controlled to inflow in the aeration reactor of high efficiency pure oxygen. 5. The T-P concentration of the separated liquid is average 723 mg/L and approximately 75% are removed by high liquid separation after a primary dewatering.

본 연구는 고령화 사회에 고층건물이 급증하는 현실을 방영하여 화재 시 노인들의 대피행동에 대한 심리적 이해를 제공하고자 총 30명의 노인들을 대상으로 고층건물 화재 대피실헙을 진행하였다. 신체적 노화과정이 심리적 상태에 영향을 미치는 노령층의 특수성을 고려하여, 노인들의 건강 및 인지상태에 대한 자신감과 위기 시 안전하게 대피할 수 있다는 자기효능감에 중점을 두었다. 분석결 과, 건강 상태에 대한 낮은 자신감은 대피공간에 대한 높은 요구와 관계가 있었으며, 시각 및 청각에 대한 자신감은 자기효능감, 공간탐색, 위기판단과 상관관계를 모였다. 반면, 실험 전 자기효능감은 실제로 이동한 층수와 부적 관계를 나타내었다. 다중회귀분석에서는 건강과 인지능력에 대한 자신 감이 자기효능감에 긍정적인 영향을 미쳤으며, 정성적 분석결과로부터 대피실험이 노인들에게 자기 효능감을 변화시킨 의미있는 경험으로 작용한다고 유추할 수 있었다. 이러한 결과는 노인들의 대피 를 위한 정책적 배려와 함께, 위기 시 현실적 자신감과 자기효능감을 갖도록 적절한 교육이 제공되 어야 함을 시사한다.

The purpose of this study was to provide psychological understanding on seniors’ behavior during fire evacuation in order to reflect the reality of the rapid growth in both seniors and high-rise buildings in Korea. A total of 30 seniors participated in this study, and the results of correlation analysis showed that (1) a low level of confidence had a relationship with a high level of needs on refuge area; (2) the level of confidence on visual and auditory status had relationships with self-efficacy, special exploration, and judgement in risk; and (3) the level of pre-experiment self-efficacy was negatively related with the number of floors they actually passed through. The result of multiple regression analysis revealed that seniors’ confidence on health and cognitive status influenced on pre-experiment self-efficacy, while the result of qualitative analysis implied that the participation in this experiment changed the seniors’ self-efficacy as a meaningful experience. It is necessary to establish a policy and provide education for seniors’ safe evacuation by considering their psychological characteristics.

본 논문에서 출력 전력 백-오프 구간을 확장하기 위한 고출력 고효율 불균형 도허티 전력 증폭기를 제안하였다. 제안된 불균형 전력증폭기는 기존의 대칭형 도허티 전력증폭기처럼 주 증폭기와 보조 증폭기에 같은 트랜지스터를 사용하는 구조이며 주 증폭기의 출력에 연결되어 있는 λ/4 변환기의 임피던스를 변형하여서 구간을 확장할 수 있다. 제안된 불균형 도허티 전력증폭기는 기존의 백-오프 출력 구간을 확장하기 위한 비대칭 도허티 전력증폭기와 비교해서 구조가 더 간단함에도 불구하고 유사한 효율과 선형성 특성을 갖는다. 제안된 증폭기의 성능을 증명하기 위해서 CDMA2000 1FA 신호를 입력으로 사용하여 46 W 도허티 전력증폭기를 설계 및 제작하였다. 제작된 불균형 도허티 전력증폭기에서 35 %의 효율과 885 kHz 오프셋 주파수에서 ACPR -34 dBc 그리고 1.98 MHz 오프셋 주파수에서 ACPR -35.6 dBcfn를 얻었다.

This paper presents a high power and high efficiency unbalanced Doherty power amplifier used to extend the output power back-off (OPBO). The proposed unbalanced amplifier uses the same type of transistors in both the main amplifier and the peaking amplifier, similar to a conventional symmetric Doherty amplifier. The unbalanced amplifier can have the impedance of a λ/4 transformer located at the output of the main amplifier modified. This enables the OPBO to exceed 6 dB, the maximum OPBO for a conventional symmetric Doherty amplifier. The efficiency and linearity performance of the unbalanced Doherty amplifier are almost same as those found for the asymmetric Doherty amplifier, even though the unbalanced Doherty amplifier structure is simpler than the asymmetric Doherty structure. In order to verify the proposed amplifier performance, a 46 W Doherty amplifier has been both simulated and measured using a CDMA2000 1FA signal. From the measured results, the proposed unbalanced Doherty amplifier achieved an added power efficiency of 38 % and an adjacent channel power ratio of -34 dBc at a 885 kHz offset frequency and -35.6 dBc at a 1.98 MHz offset frequency.