• 열처리공학회지
• /
• 제18권3호
• /
• pp.157-163
• /
• 2005

Effects of refinement of primary Si and residual stress on the mechanical properties of Aluminum B.390 alloy have been examined. Calcium was found to have an effect on the size of primary silicon particles. Primary silicon particle was refined as Ca content decreased. Refinement of primary Si particles led to an improvement in mechanical properties of the alloy; increase of elongation was prominent, above all. By the increase of compressive residual stress in the matrix alloy, tensile strength increased but elongation decreased.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권1호
• /
• pp.20-33
• /
• 2015

Spectrum sensing is a key component of cognitive radio. The prediction of the primary user status in a low signal-to-noise ratio is an important factor in spectrum sensing. However, because of noise uncertainty, secondary users have difficulty distinguishing between the primary signal and an unauthorized signal when an unauthorized user exists in a cognitive radio network. To resolve the sensitivity to the noise uncertainty problem, we propose an entropy-based spectrum sensing scheme to detect the primary signal accurately in the presence of an unauthorized signal. The proposed spectrum sensing uses the conditional entropy between the primary signal and the unauthorized signal. The ability to detect the primary signal is thus robust against noise uncertainty, which leads to superior sensing performance in a low signal-to-noise ratio. Simulation results show that the proposed spectrum sensing scheme outperforms the conventional entropy-based spectrum sensing schemes in terms of the primary user detection probability.

• 한국세라믹학회지
• /
• 제27권2호
• /
• pp.211-218
• /
• 1990

CA2-based clinker with highly activated surface and hydraulic properties was synthesized at a comparatively lowr temperature than that of conventional synthesis by "hydration-burning method". This consists of calcining the mixture of CaCO3 and Al2O3 to obtain a primary clinker, hydrating the primary clinker and reburning the hydrates to obtain final clinker. Burning of primary clinker above 1200℃ was necessary to eliminate free CaO in it and to obtain it's solid hydrate. However, rising the burning temperature above 1300℃ is ineffective due to the decrease in hydraulic properties of the primary clinker with the temperature. Hydration of primary clinker at the elevated temperature(>35℃) was required to obtain the hydrate with more porous structure and final clinker with more active surface. CA2 was formed and increased with temperature at above 1150℃, finally became a primary phase of the final clinker. However, burning at the temperature above 1300℃ resulted in reverse effect on the hydraulic properties of the final clinker due to rapid decrease in it's surface area with the temperature.

• BMB Reports
• /
• 제49권10호
• /
• pp.572-577
• /
• 2016

The short gastrulation (sog) shadow enhancer directs early and late sog expression in the neurogenic ectoderm and the ventral midline of the developing Drosophila embryo, respectively. Here, evidence is presented that the sog primary enhancer also has both activities, with the late enhancer activity dependent on the early activity. Computational analyses showed that the sog primary enhancer contains five Dorsal (Dl)-, four Zelda (Zld)-, three Bicoid (Bcd)-, and no Single-minded (Sim)-binding sites. In contrast to many ventral midline enhancers, the primary enhancer can direct lacZ expression in the ventral midline as well as in the neurogenic ectoderm without a canonical Simbinding site. Intriguingly, the impaired transcriptional synergy between Dl and either Zld or Bcd led to aberrant and abolished lacZ expression in the neurogenic ectoderm and in the ventral midline, respectively. These findings suggest that the two enhancer activities of the sog primary enhancer are functionally consolidated and geographically inseparable.

• 대한두경부종양학회지
• /
• 제15권1호
• /
• pp.80-84
• /
• 1999

Primary hryperparathyroidism is a relatively rare disease entity in Korea. It's characterized by severe skeletal and renal changes due to hypersecretion of parathyroid hormone, and rarely shows peptic ulceration, hypertension, pancreatitis and impaired mentality. Recently the determination of the serum calcium level has become a routine laboratory test and the awareness of primary hyperparathyroidism has been incerased, the disease is being diagnosed with increasing frequency. Primary hyperparathyroidism is most commonly caused by parathyroid adenoma and rarely hyperplasia, cancer of parathyroid glands. The authors operated sucessfully a case of primary parathyroid adenoma by diagnosed by nuclear medical diagnostic work-up. The patient had anterior neck mass(soft, non tender nodule) on physical examination, multiple goiter on thyroid ultrasonogram and scan. The parathyroid lesion was difficult to find preoperatively.

• 아동학회지
• /
• 제6권2호
• /
• pp.1-20
• /
• 1985

The relationship between home environment variables for infants and toddlers and the nature of primary caregivers were examined in the present study. The purpose of the study was to explore the possibility of home stimulation deprivation when infants were not cared by their own mothers. Primary caregivers were classified into mothers, blood related adults, and unrelated adults. The home environment was assessed with the Korean version of HOME (Home Observation for Measurement of the Environment) by means of interview and observation. The subjects of this study were 126 infants aged 3 to 36 months and their primary caregiver, adults who provided more than 8 hours day-time care for infants at home. The results were as follows : 1) The primary caregiver had an effect on the infants' home environmental stimulation. That is, the group of mothers as primary caregivers had the highest HOME scores, the second highest were blood related adults, and the unrelated adults were the last. 2) There were no sex differences in HOME scores. 3) There were significant relationships between the educational level of the caregiver and HOME. That is, the higher educational levels showed higher HOME scores.

• 수산해양교육연구
• /
• 제23권3호
• /
• pp.533-548
• /
• 2011

This study examined the concern levels of primary school teachers regarding transitional education from early childhood phase to primary education. Concern Based Adoption Model (CBAM) instrument of Hall and Hord (2006) was used to survey 104 primary school teachers. The results indicated that the majority of respondents' concern level was at 'informational' level (stage 1). And first peak of concern level was at 'unconcerned' level (stage 0). The first-second peak analysis of stage 0 (unconcerned) group indicated that there were 5 types of groups and each had distinguished features. Finally there were statistical differences at the unconcerned stage by in-service training and career of the first-year class. A discussion of the limitations of this study and implications for teacher education programs and operational support systems were suggested.

• 전자공학회논문지B
• /
• 제31B권6호
• /
• pp.63-70
• /
• 1994

In this paper, we propose a fault simulation method based on primary output in combinational circuit. In the deterministic test pattern generation, each test pattern is genterated incrementally. The test pattern is applied to the primary inputs of circuit under test to simulate faults. We detect the faults with respect to each primary output. The fault detection with resptect to each primary output is reflected by the corresponding bit in the detection words, and efficient fault detection for the reconvergent fan-out stem is achieved with dynamic fault propagation. As an experimental result of the fault simulation with our method for the several bench mark circuits, we illustrated the good performance showing that the number of gates to be activated is much reduced as compared with other method which is not based on primary output.

• Journal of Communications and Networks
• /
• 제13권1호
• /
• pp.50-55
• /
• 2011

Spectrum leasing for cognitive radio (CR) networks is an effective way to improve the spectrum utilization. This paper presents an opportunistic relaying based spectrum leasing for CR networks where the primary users lease their frequency band to the cognitive users. The cognitive users act as relays for the primary users to improve the channel capacity, and this improved capacity is used for the transmission of secondary users' data. We show that the cognitive users can use a significant portion of the communication resource of primary networks while maintaining a fixed target data rate for the primary users. Moreover, the primary network is also benefited by the cooperating cognitive users in terms of outage probability. Information theoretic analysis and simulation results are presented to evaluate the performances of both primary and cognitive networks.

• 반도체디스플레이기술학회지
• /
• 제4권2호
• /
• pp.11-14
• /
• 2005

In plasma processing reactors, it is common practice to control plasma density and ion bombardment energy by manipulating excitation voltage and frequency. In this paper, a dually excited capacitively coupled rf plasma reactor is self-consistently simulated with a three moment model. Effects of phase differences between primary and secondary voltage waves, simultaneously modulated at various combinations of commensurate frequencies, on plasma properties are investigated. The simulation results show that plasma potential and density as well as primary self-dc bias are nearly unaffected by the phase lag between the primary and the secondary voltage waves. The results also show that, with the secondary frequency substantially lower than the primary frequency, secondary self·do bias remains constant regardless of the phase lag. As the secondary frequency approaches to the primary frequency, however, the secondary self-dc bias becomes greatly altered by the phase lag, and so does the ion bombardment energy at the secondary electrode. These results demonstrate that ion bombardment energy can be more carefully controlled through plasma simulation.