• 한국인터넷방송통신학회논문지
• /
• 제16권3호
• /
• pp.145-153
• /
• 2016

본 연구는 국내 케이블 TV의 디지털 전환 과정의 지체 요인을 분석하고 유료방송 시장의 경쟁 상황이 디지털 전환에 미치는 영향을 살펴보았다. 디지털 전환의 지체 요인은 케이블 TV 사업자의 의지 및 역량의 부족, 정책적 지원과 강제의 부재 및 시청자의 수용 의지와 관련된 요소로 나타났다. 아날로그 방송을 통하여 지속적인 수익을 올리며 유료방송시장에서 독점적 지위를 가지고 있던 케이블 TV 사업자는 추가적인 투자가 필요한 디지털 전환에 대하여 적극적으로 대처하지 못했다. 저소득층에 대한 지원이나 아날로그 케이블 TV 방송의 종료 기준 설정 부재 등 정책적인 뒷받침도 이루어지지 못했다. 디지털 상품에 대한 가격 저항감이나 조작의 편의성 선호 등 시청자의 수용 요인도 디지털 전환에 영향을 미쳤다. 2008년에 IPTV가 시장에 진입하며 유료방송시장에 실질적인 경쟁 상황이 형성되었으며 이는 케이블 TV 사업자의 디지털 전환 속도에 영향을 미친 것으로 나타났다.

• Composites Research
• /
• 제20권5호
• /
• pp.56-63
• /
• 2007

복소퍼텐셜을 이용하여 타원공 또는 균열을 내재한 복합재 적층판구조 해석법을 고찰하였다. 복합재 적층판은 충격에 취약하며 이러한 충격손상은 타원공이나 균열형태의 노치로 모델화된 바 있다. 이와 같이 컷아웃부를 내재한 복잡한 형태의 복합재 적층판 해석에 유한요소해석법이 널리 사용되고 있으나 피로하중 하에서의 손상허용성 평가와 같이 손상진전에 따라 반복적으로 유한요소모델링을 수정하여 해석을 수행하여야 하는 경우 매우 번거로운 작업이 요구된다. 이러한 관점에서 복소퍼텐셜을 이용한 해석적 기법은 매우 간편하고 사용하기 손쉬운 기법이라고 할 수 있다. 이러한 해석법에 의한 계산결과를 유한요소해석 결과와 비교 분석함으로써 계산과정의 유효성과 용이성을 검증하였다.

• Journal of electromagnetic engineering and science
• /
• 제11권2호
• /
• pp.128-132
• /
• 2011

In interference tolerance based spectrum sharing systems, primary receivers (PRs) are protected by a predefined peak or average interference power constraint. To implement such systems, cognitive radio (CR) transmitters are required to adjust their transmit power so that the interference power received at the PR receivers is kept below the threshold value. Hence, a CR-transmitter requires knowledge of its channel and the primary receiver in order to allocate the transmit power. In practice, it is impossible or very difficult for a CR transmitter to have perfect knowledge of this channel state information (CSI). In this paper, we investigate the impact of imperfect knowledge of this CSI on the performances of both a primary and cognitive radio network. For fixed transmit power, average interference power (AIP) constraint can be maintained through knowledge of the channel distribution information. To maintain the peak interference power (PIP) constraint, on the other hand, the CR-transmitter requires the instantaneous CSI of its channel with the primary receiver. First, we show that, compared to the PIP constraint with perfect CSI, the AIP constraint is advantageous for primary users but not for CR users. Then, we consider a PIP constraint with imperfect CSI at the CR-transmitter. We show that inaccuracy in CSI reduces the interference at the PR-receivers that is caused by the CR-transmitter. Consequently the proposed schemes improve the capacity of the primary links. Contrarily, the capacities of the CR links significantly degrade due to the inaccuracy in CSI.

• Nuclear Engineering and Technology
• /
• 제53권10호
• /
• pp.3335-3343
• /
• 2021

The impact of gamma radiation on a commercial off the shelf microcontroller board has been investigated. Three different tests have been performed to ascertain the radiation tolerance of the device from a nuclear decommissioning deployment perspective. The first test analyses the effect of radiation on the output voltage of the on-board voltage regulator during irradiation. The second test evaluated the effect of gamma radiation on the voltage characteristics of analogue and digital inputs and outputs. The final test analyses the functionality of the microcontroller when using an external, shielded voltage regulator instead of the on-board voltage regulator. The results suggest that a series of latch-ups occurs in the microcontroller during irradiation, causing increased current drain which can damage the voltage regulator if it does not have short-circuit protection. The analogue to digital conversion functionality appears to be more sensitive to gamma radiation than digital and analogue output functionality. Using an external, shielded voltage regulator can prove beneficial when used for certain applications. The collected data suggests that detaching the voltage regulator can extend the lifespan of the platform up to approximately 350 Gy.

• Journal of Power Electronics
• /
• 제16권3호
• /
• pp.840-848
• /
• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• Journal of Microbiology and Biotechnology
• /
• 제30권7호
• /
• pp.1082-1091
• /
• 2020

Microbial transglutaminases (MTGs) are widely used in the food industry. In this study, the MTG gene of Streptomyces sp. TYQ1024 was cloned and expressed in a food-grade bacterial strain, Bacillus subtilis SCK6. Extracellular activity of the MTG after codon and signal peptide (SP Ync M) optimization was 20 times that of the pre-optimized enzyme. After purification, the molecular weight of the MTG was 38 kDa and the specific activity was 63.75 U/mg. The optimal temperature and pH for the recombinant MTG activity were 50℃ and 8.0, respectively. MTG activity increased 1.42-fold in the presence of β-ME and 1.6-fold in the presence of DTT. Moreover, 18% sodium chloride still resulted in 83% enzyme activity, which showed good salt tolerance. Cross-linking gelatin with the MTG increased the strength of gelatin 1.67 times and increased the thermal denaturation temperature from 61.8 to 75.8℃. The MTG also significantly increased the strength and thermal stability of gelatin. These characteristics demonstrated the huge commercial potential of MTG, such as for applications in salted protein foods.

• The Korean Journal of Ecology
• /
• 제15권2호
• /
• pp.157-172
• /
• 1992

Studies were conducted to evaluate the differential al tolerance of suwon 205 and olmil wheats grown is nutrient solution and determine the impact of NH4+-N or Ca2+ nutrition of the response of the two wheat vareties to al. In various concentrations of al, olmil induced lower ph levels than suwon 205 in nutrient solutions and the reduction of root length and dry weight was greater in olmil than in suwon 205. The uptake of al was greater in root than in shoot of the two wheat varieties, but more increased in root of olimil. also the uptake of ca, mg, k and p was inhibited by al especialy decrease of ca and p uptake in roots of olmil was more pronounced than in those of suwon 205. In nutrient solutions that contained NH4+-N plus 9ppm al, the ability of both varienties to raise the ph was reduced as the level of NH4+-N in nutrient solutions was increased, and al-sensitive olimil induced lower ph than did al-tolerant suwon 205. al toxicity was intensified by increasing the concentration of NH4+-N in nurient and toxic effect was greater in olmil. al toxicity in the two wheat varieties was steadily increased as the ca level of nutrient solution was reduced, sepecialy this effect was stronger in al-sensitive olmil than in al-tolerant suwon 205.

• 가정과삶의질연구
• /
• 제32권1호
• /
• pp.63-79
• /
• 2014

Recently, in our society, the use of smartphones has been widespread and changed our lives positively; however, the excessive use of smartphones has also produced many side effects. In particular, we can see that the reckless use of smartphones has constantly increased smartphone addiction propensities. University students, too, show smartphone addiction propensities more and more gradually; therefore this study intends to perform research related with smartphone addiction propensities with university students as the subjects. Since it is more and more important to perform leisure activities to prevent smartphone addiction and reduce addiction propensities, it can be said that the research on the correlation between leisure activities and smartphone addiction propensities is significant. The major findings of the research are as follows: First, among the smartphone addiction propensities, their tolerance and disturbance of adaptive function were relatively higher than other factors. Second, overall smartphone addiction affects the variables of gender (male), school year (freshmen), economic leisure constraints, time leisure constraints, and the adequacy of travel behavior, sports behavior, media use behavior, reading behavior, volunteer work and religious behavior. The adequacy of the media use behavior variables showed the greatest impact.

• Journal of Electrical Engineering and Technology
• /
• 제12권1호
• /
• pp.310-316
• /
• 2017

The robot proximity and tactile sensors can be categorized into two groups: grip sensors and safety sensors. They have different performance requirements. The safety sensor should have long proximity range and fast response in order to secure enough response time before colliding with ambient objects. As for the tactile sensing function, the safety sensor need to be fast and compliant to mitigate the impact from a collision. In order to meet these requirements, we proposed and demonstrated a compliant integrated safety sensor suitable to human-friendly robots. An ultrasonic proximity sensor and a piezoelectric tactile sensor made of PVDF films have been integrated in a compliant PDMS structure. The implemented sensor demonstrated the maximum proximity range of 35 cm. The directional tolerance for 30 cm detection range was about ${\pm}15^{\circ}$ from the normal axis. The integrated PVDF tactile sensor was able to detect various impacts of up to 20 N in a controlled experimental setup.

• IMMUNE NETWORK
• /
• 제16권1호
• /
• pp.13-25
• /
• 2016

Dendritic cells (DCs) are considered to play major roles during the induction of T cell immune responses as well as the maintenance of T cell tolerance. Naive CD4⁺ T cells have been shown to respond with high plasticity to signals inducing their polarization into effector/helper or regulatory T cells. Data obtained from in vitro generated bone-marrow (BM)-derived DCs as well as genetic mouse models revealed an important but not exclusive role of DCs in shaping CD4⁺ T cell responses. Besides the specialization of some conventional DC subsets for the induction of polarized immunity, also the maturation stage, activation of specialized transcription factors and the cytokine production of DCs have major impact on CD4⁺ T cells. Since in vitro generated BM-DCs show a high diversity to shape CD4⁺ T cells and their high similarity to monocyte-derived DCs in vivo, this review reports data mainly on BM-DCs in this process and only touches the roles of transcription factors or of DC subsets, which have been discussed elsewhere. Here, recent findings on 1) the conversion of naive into anergic and further into Foxp3^- regulatory T cells (Treg) by immature DCs, 2) the role of RelB in steady state migratory DCs (ssmDCs) for conversion of naive T cells into Foxp3⁺ Treg, 3) the DC maturation signature for polarized Th2 cell induction and 4) the DC source of IL-12 for Th1 induction are discussed.