• 전기학회논문지P
• /
• 제51권3호
• /
• pp.120-125
• /
• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• 전자공학회논문지CI
• /
• 제47권4호
• /
• pp.63-70
• /
• 2010

IEEE 802.11e에서는 CSMA/CA 전송방식으로 차별화된 서비스를 제공한다. 하지만 노드 수가 증가함에 따른 충돌확률 증가, 차등 전송모드에 따라 나타나는 전송속도 하향평준화, TCP의 흐름제어 특성으로 인해 UDP와 링크를 공유하게 될 경우 UDP가 링크를 모두 잠식하는 결과로 TCP 전송률이 저하되는 문제가 발생한다. 따라서 본 논문에서는 IEEE 802.11e에서 현재 접속된 노드의 수에 따라 초기 경쟁 윈도우의 최소값과 최대값을 다르게 설정하여 충돌을 회피하였고, 채널 상태에 따라 TXOP를 조정하여 우선순위는 낮지만 채널 상태가 좋은 AC에게도 점차적으로 할당함으로써 채널을 최대한으로 활용하도록 하였고, TCP 전송의 흐름제어에 사용되는 ACK 신호에 우선순위를 높여 전송함으로써 흐름제어를 좋게 하여 UDP 플로우로 잠식되는 현상을 줄여 공정한 전송이 되도록 개선하여 자원의 능동적인 할당으로 전송률 향상에 기여하는 알고리듬을 제안하였다.

• 한국의상디자인학회지
• /
• 제22권1호
• /
• pp.33-44
• /
• 2020

The purpose of this study is to guide the research direction for securing the competitiveness of the textile industry by analyzing the trends of patent technology development for flexible materials and platform technologies of domestic and overseas textiles used for wearable devices. The study is based on patents from Korea (KIPO), USA (USPTO), Japan (JPO), Europe (EPO), PCT (WO), and China (SIPO), which were registered as of December 31, 2017. The analysis utilized 3,643 patents acquired from the WINTELIPS search DB. The technology classification system for patent analysis was divided into evangelist-based textile technology developments: human body (AA), fiber attachment patch development (AB), and service platform development (AC). The analysis findings are as follows: 1. The development of flexible materials and platform technologies for textile-based wearable devices has increased since 2000. In particular, China (SIPO) had the most patents. 2. In China, Japan, and Korea, most patent applicants are applied for by natives, but the US has a high proportion of foreigners applying for patents. 3. As for the amount of development of the evangelist-based textile technology (AA) was the most common with 1,203 (33%) cases. As a result of the above IP historical analysis, it can be seen that as a result of the global competition, domestic companies need to acquire IRP and standard technology, and promote commercialization by applying their products to smart wearables devices and other products.

• 한국유체기계학회 논문집
• /
• 제17권6호
• /
• pp.104-108
• /
• 2014

The recent Fukushima nuclear power plant accidents shows that the core make up at high RCS pressure condition is very important to prevent core melting. The core make up flow at high pressure condition should be driven by gravity force or passive forces because the AC-powered safety features are not available during a Station Black Out (SBO) accident. The reactor Coolant System (RCS) mass inventory is continuously decreased by releasing steam through the pressurizer safety valves after reactor trip during a SBO accident. The core will be melted down within 2~3 hours without core make up action by active or passive mode. In the new design concept of a Hybrid Safety Injection Tank (Hybrid SIT) both for low and high RCS pressure conditions, the low pressure nitrogen gas serves as a charging pressure for a LBLOCA injection mode, while the PZR high pressure steam provides an equalizing pressure for a high pressure injection mode such as a SBO accident. After the pressure equalizing process by battery driven initiation valve at a high pressure SBO condition, the Hybrid SIT injection water will be passively injected into the reactor downcomer by gravity head. The SBO simulation by MARS code show that the core makeup injection flow through the Hybrid SIT continued up to the SIT empty condition, and the core heatup is delayed as much.

• Journal of Plant Biotechnology
• /
• 제6권2호
• /
• pp.91-96
• /
• 2004

The use of liquid-medium-based procedure relative to the solid media led to a 4.5-fold increase in the number of cotyledon-stage embryos. The most efficient system for multiplication and regeneration of somatic embryos was CP6 procedure with the media MSD40/MSD20/MSM6AC/FNL0S3S3GM. However, the rate of regeneration was lower. About 71％ of the embryos with dicotyledon were continued to develop the roots after desiccation treatment and 92％ of the germinated embryos produced shoots in 10 days. Of the four morphologically different types of embryos, dicotyledonous ones showed a high frequency of conversion, while only a few with fused and horn type cotyledon developed shoots. Mature somatic embryos were desiccated in empty petri dishes for 12-72 h. Embryo survival rate was the highest after 12 h of desiccation, but maximal germination was observed at 24 h. After desiccation, they were placed on MS medium without growth regulators for germination. Germinating embryos were transferred to small pots with vermiculite for plant regeneration. The etiolating the plants during the growth was resolved to add 1％ activated charcoal on hormone-free MS medium.

• Molecular & Cellular Toxicology
• /
• 제5권2호
• /
• pp.160-164
• /
• 2009

Notch signaling plays a crucial role in development of the nervous system. Neurodevelopmental hypothesis on etiology of schizophrenia has been implicated. The aim of this study is to determine whether single nucleotide polymorphisms (SNPs) of Notch homolog 4 (Drosophila) (NOTCH4) gene are associated with schizophrenia. This study included 283 schizophrenia patients diagnosed according to DSM-IV and 301 normal control subjects. Control subjects without history of psychiatric disorders were recruited. Four missense SNPs [rs915894 (exon 3, Lys117Gln), rs2071282 (exon 4, Pro204Leu), rs422951 (exon 6, Thr320Ala), and rs17604492 (exon 18, Gly942Arg)] of NOTCH4 gene were genotyped by the direct sequencing method. Multiple logistic regression models (codominant, dominant, and recessive models) were employed to evaluate odds ratio, 95% confidence interval, and p value. For analysis of genetic data, SNPStats, Haploview, HapAnalyzer, SNPAnalyzer, and Helixtree programs were also used. Of 4 SNPs, rs2071282 was weekly associated with schizophrenia in two alternative models (codominant model, P=0.049; dominant, P=0.041). However, these associations were not significant after Bonferroni correction. At 4 SNPs, one linkage disequilibrium (LD) block was made. This block consisted of rs915894 and rs2071282. In haplotype analysis, AC haplotype was weakly associated with schizophrenia (dominant, P=0.04). This association was disappeared after Bonferroni correction. Our result shows possibility that some SNPs of NOTCH4 gene may be weekly associated with development of schizophrenia in Korean population. However, replication result by other population will be needed.

• Journal of Advanced Marine Engineering and Technology
• /
• 제10권2호
• /
• pp.156-164
• /
• 1986

In the case of boiling on high temperature wall, vapor film covers fully or parcially the surface. This phenomenon, film boiling or transition boiling, is very important in the surface heat treatment of metal, design of cryogenic heat exchanger and emergency cooling of nuclear reactor. Mainly supposed hydraulic-thermal accidents in nuclear reactor are LCCA (Loss of Coolant Accident) and PCM (Power-Cooling Mismatch). Recently, world-wide studies on reflooding of high temperature rod bundles after the occurrence of the above accidents focus attention on wall temperature history and required time in transient cooling process, wall superheat at rewet point, heat flux-wall superheat relationship beyond the transition boiling region, and two-phase flow state near the surface. It is considered that the further systematical study in this field will be in need in spite of the previous results in ref. (2), (3), (4). The paper is the study about the fast transient cooling process following the wall temperature excursion under the CHF (Critical Heat Flux) condition in a forced convective subcooled boiling system. The test section is a vertically arranged concentric annulus of 800 mm long and 10 mm hydraulic diameter. The inner tube, SUS 304 of 400 mm long, 8 mm I.D, and 7 mm O.D., is heated uniformly by the low voltage AC power. The wall temperature measurements were performed at the axial distance from the inlet of the heating tube, z=390 mm. 6 chromel- alumel thermocouples of 76 .mu.m were press fitted to the inner surface of the heating tube periphery. To investigate the heat transfer characteristics during the fast transient cooling process, the outer surface (fluid side) temperature and the surface heat flux are computed from the measured inner surface temperature history by means of a numerical method for inverse problems of transient heat conduction. Present cooling (boiling) curve is sufficiently compared with the previous results.

• 생약학회지
• /
• 제2권1호
• /
• pp.23-28
• /
• 1971

This study was planned to see whether the Panax Ginseng root has any influence upon the emotionality in rats exposed to a novel open-field and induced by a grid shock. Sixty four male albino rats whose body weight ranged from 130 to 180 gm were used. They were divided into four groups, i.e., placebo control group, 5mg/kg Ginseng ext. group, 10mg/kg Ginseng ext. group, and 20mg/kg Ginseng ext. group. Sixteen rats were subjected in each group. Open-field activity was measured in a $2.20m\;{\times}\;2.20m$ open-field that was divided into 15cm squares. Four novel objects and food pellets were put with an equal distance in the open-field. Locomotion was recorded by entering the number of squares traversed for 4 min. and behaviors which were shown at the 10-sec. period were checked by a modified Jarrad and Bunnel's observation procedure. Sensitivity to the grid shock was measured in a compartment of shuttle box. 10, 20, 30, 40, 50, 60 and 70 volt ac. 2 sec., electric shock were delivered in each subject by the grid to animal's feet. Flinch, vocalization and jumping responses were rated in each shock level. The results obtained were as follows: 1.) 5mg/kg and 10mg/kg Ginseng ext. groups were tended to increase the ambulation and exploration compared with placebo control. 2.) All Ginseng extract groups were defecated significantly less often than placebo control in the open-field and shock situation. 3.) Thresholds to the electric shock were tended to elevate in all Ginseng groups. 4.) These results suggest that Ginseng extract has a stimulant action in open-field and a tranqulizing action in feared situation.

• The Plant Pathology Journal
• /
• 제28권1호
• /
• pp.40-48
• /
• 2012

$Potato$ $virus$ $X$ (PVX) replication is precisely regulated by regulatory viral sequences and by viral and/or host proteins. In a previous study, we identified a 54-kDa cellular tobacco protein that bound to a region within the first 46 nucleotides (nt) of the 5' non-translated region (NTR) of the viral genome. Optimal binding was dependent upon the presence of an ACCA sequence at nt 10-13. To identify host factors that bind to 5' NTR elements including AC-rich sequences as well as stemloop 1 (SL1), we used northwestern blotting and matrixassisted laser desorption/ionization time-of-flight mass spectrometry for peptide mass fingerprinting. We screened several host factors that might affect PVX replication and selected a candidate protein, $Nicotiana$ $tabacum$ WRKY transcription factor 1 (NtWRKY1). We used a $Tobacco$ $rattle$ $virus$ (TRV)-based virus-induced gene silencing (VIGS) system to investigate the role of NtWRKY1 in PVX replication. Silencing of $WRKY1$ in $Nicotiana$ $benthamiana$ caused lethal apical necrosis and allowed an increase in PVX RNA accumulation. This result could reflect the balancing of PVX accumulation in a systemic $N.$ $benthamiana$ host to maintain PVX survival and still produce a suitable appearance of mosaic and mottle symptoms. Our results suggest that PVX may recruit the WRKY transcription factor, which binds to the 5' NTR of viral genomic RNA and acts as a key regulator of viral infection.

• 한국정밀공학회지
• /
• 제19권4호
• /
• pp.93-100
• /
• 2002

The current from the feed motor of a machine tool contains substantial information about the machining state. There have been many researches that investigated the current as a measure for the cutting farces. However it has been reported that this indirect measurement of the cutting farces from the feed motor current is only feasible in low frequency. In this research, it was presented that the bandwidth of the current monitoring can be expanded to 130 Hz. And the unusual behavior of the current was examined in this bandwidth. The cross-feed directional cutting force influences the machined surface of the workpiece, which makes it necessary to estimate this force to control the roughness of the machined sulfate. The current exists in the stationary feed motor, and it can give the useful information on the quality of the machined surface. But the unpredictable behavior of the current prevents applying the current to prediction of the cutting state. Empirical approach was conducted to resolve the problem. As a result, the current was shown to be related to the accumulation of the accumulation of the infinitesimal rotation of the motor. rotation of the motor. Subsequently the relationship between the current and the cutting force was identified.