• The Korean Journal of Zoology
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• v.8 no.2
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• pp.37-41
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• 1965

The frequency and pattern of sex chromatin in primary cultured cells of kidney cortex of cats and guinea-pigs, and muscle of chick embroys were examined and compared to those of in vivo condition, with special reference to the various cultured stages. 1. In cat, the frequencies of sex chromatin positive I of peripheral position were average 62.7% in female, and 15% in male, whereas those of non-peripherla position were 5.8% in female and 0.1% in male. The incident proportion between them showed a marked difference-approximately 10 times higher in female than male. These results failry indicated that a distinct nuclear dimorphism with regard to the sex chromatin positive I was established in cultured cells. The position of sex chormatin was usually peripheral location. The tendency of frequencies , with reference to the cultured stages, was low count in primary extracted and initial stage cells , but it showed a peaked frequency in 10-13 days after primary culture, and after that the frequencies were decreased gradually. Compared between I vitro and in vivo condition of the same tissues, the cells in vivo exhibited the sex chromatin in high frequency at the peak showed stage. 2. In guinea-pig , the frequencyies of peripheral positive I were 36.8% in female and 6.3% in male, while non-peripheral positions were 6.1% in female and 3.5% inmale. Its incident was a rate of nearly 4 times higher in female than male. The nuclear dimorphism was also established in cultrued cells of guinea-pig. The position and the incident frquency showed a similar pattern as in cat except the primary extracted cells. 3. In chick embryo, the frequencies of sex chromatin positive I of peripheral position were 38.2% in female, and 18.3% in male, non-peripheral position, however, was hardly to find. These results suggest that the definite sexual dimorphism was unable to find in chick embryo cultured cells. The position and the incident tendency were a similar pattern as in above mammals and the frequency was higher in vitro cells.

• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.579-590
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• 2018

The lakes' metabolism bears important information for the assessment of the carbon budget due to the accumulation or loss of carbon in the lake as well as the dynamics of the food webs through primary production. A lake-scale metabolism is evaluated by Gross Primary Production (GPP), Ecosystem Respiration (R), and Net Ecosystem Production (NEP), which is the difference between the first two values. Methods for estimating GPP and R are based on the levels carbon and oxygen. Estimation of carbon is expensive because of the use of radioactive materials which requires a high degree of proficiency. The purpose of this study was to estimate Lake Daecheong ecosystem metabolism using high frequency water temperature data and DO measurement sensor, widely utilized in the field of water quality monitoring, and to evaluate the possibility of using the application method. High frequency data was collected at intervals of 10 minutes from September to December 2017 by installing a thermistor chain and a DO sensor in downstream of Daechung Dam. The data was then used to estimate GPP, R and NEP using the R public program LakeMetabolizer, and other metabolism models (mle, ols, kalman, bookkeep). Calculations of gas exchange coefficient methods (cole, crusius, heiskanen, macIntyre, read, soloviev, vachon) were compared. According to the result, Lake Daecheong has some deviation based on the application method, but it was generally estimated that the NEP value is negative and acts as a source of atmospheric carbon in a heterotrophic system. Although the high frequency sensor data used in this study had negative and positive GPP and R values during the physical mixing process, they can be used to monitor real-time metabolic changes in the ecosystem if these problems are solved.

• Journal of Power Electronics
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• v.18 no.1
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• pp.212-224
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• 2018

For maintaining a reliable and secure power system, this paper describes the design and implement of a single-phase grid-connected inverter with an enhanced phase-locked loop (PLL) and excellent power control performance. For designing the enhanced PLL and power regulator, a full-bridge voltage-controlled inverter (VCI) is investigated. When the grid frequency deviates from its reference values, the output frequency of the VCI is unstable with an oscillation of 2 doubling harmonics. The reason for this oscillation is analyzed mathematically. This oscillation leads to an injection of harmonics into the grid and even causes an output active power oscillation of the VCI. For eliminating the oscillation caused by a PLL, an oscillation compensation method is proposed. With the proposed method, the VCI maintains the original PLL control characteristics and improves the PLL robustness under grid frequency deviations. On the basis of the above analysis, a power regulator with the primary frequency and voltage modulation characteristics is analyzed and designed. Meanwhile, a small-signal model of the power loops is established to determine the control parameters. The VCI can accurately output target power and has primary frequency and voltage modulation characteristics that can provide active and reactive power compensation to the grid. Finally, simulation and experimental results are given to verify the idea.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.1
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• pp.58-71
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• 2019

This paper proposes architecture of a cognitive radio engine platform and the allowable frequency channel reasoning method that enables acquisition of the allowable channels for the military tactical network environment. The current military tactical wireless communication system is increasing need to secure a supplementary radio frequency to ensure that multiple wireless networks for different military wireless devices coexist, so that tactical wireless communication between the same or different systems can be operated effectively. This paper presents the allowable frequency channel reasoning method based on cognitive radio engine for realizing DSA(Dynamic Spectrum Access) as an optimal available frequency channel. To this end, a case-based allowable frequency channel reasoning method for cognitive radio devices is proposed through modeling of primary user's traffic status and calculation of channel occupancy probability. Also through the simulation of the performance analysis, changing rate of collision probability between the primary users' occupancy channel and the available channel acquisition information that can be used by the cognitive radio device was analysed.

• Journal of information and communication convergence engineering
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• v.12 no.2
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• pp.97-103
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• 2014

In spectrum sensing, there is a tradeoff between the probability of missed detection and the probability of a false alarm according to the value of the sensing threshold. Therefore, it is important to determine the sensing threshold suitable to the environment of cognitive radio networks. In this study, we consider a cognitive radio-based ad hoc network where secondary users directly communicate by using the same frequency band as the primary system and control their transmit power on the basis of the distance between them. First, we investigate a condition in which the primary and the secondary users can share the same frequency band without harmful interference from each other, and then, propose an algorithm that controls the sensing threshold dynamically on the basis of the transmit power of the secondary user. The analysis and simulation results show that the proposed sensing threshold control algorithm has low probabilities of both missed detection and a false alarm and thus, enables optimized spectrum sharing between the primary and the secondary systems.

• Fashion & Textile Research Journal
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• v.6 no.5
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• pp.558-564
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• 2004

The purpose of this study was to examine the design characteristics of women's swimwear from 1955 to 1969 in Korea using documentary research sources. Both visual and linguistic elements found in the illustrations and advertisements that appeared in periodicals from 1955 to 1969 were used as primary sources. The primary sources were 아리랑, 여상, 여성계, 여성동아, 여원, 주부생활. The methods of content analysis and frequency seriation were combined to analyze the data obtained from the primary sources. Seriational analysis of the data were performed by ordering the frequency chronologically for the entire fifteen-year period. As the result of the study, it was found that the design of the swimwear during this period changed consistently in terms of swimwear type, shape of thigh line, textile design and decorative details. The degree of skin exposure was also continuously increased in different body parts.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.155-156
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• 2015

This paper proposes a high efficiency wireless power transfer system with an asymmetric 4-coil resonator. It presents a theoretical analysis, an optimal design method, and experimental results. In the proposed asymmetric 4-coil system, the primary side consists of a source coil and two transmitter coils which are called intermediate coils, and in the secondary side, a load coil serves as a receiver coil. In the primary side, two intermediate coils boost the apparent coupling coefficient at around the operating frequency. Because of this double boosting effect, the system with an asymmetric 4-coil resonator has a higher efficiency than the conventional symmetric 4-coil system. The prototype operates at 90 kHz ofswitching frequency and has 200 mm of the power transmission distance between the primary side and the secondary side. An AC-DC overall system efficiency of 96.56% has been achieved at 3.3 kW of output power.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1254-1266
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• 2024

This study investigates the application of supercritical carbon dioxide (S-CO₂) direct-cycle micro modular reactors (MMRs) in primary frequency control (PFC), which is a scenario characterized by significant load fluctuations that has received less attention compared to secondary load-following. Using a modified GAMMA + code and a deep neural network-based turbomachinery off-design model, the authors conducted an analysis to assess the behavior of the reactor core and fluid system under different PFC scenarios. The results indicate that the acceptable range for sudden relative electricity output (REO) fluctuations is approximately 20%p which aligns with the performance of combined-cycle gas turbines (CCGTs) and open-cycle gas turbines (OCGTs). In S-CO₂ direct-cycle MMRs, the control of the core operates passively within the operational range by managing coolant density through inventory control. However, when PFC exceeds 35%p, system control failure is observed, suggesting the need for improved control strategies. These findings affirm the potential of S-CO₂ direct-cycle MMRs in PFC operations, representing an advancement in the management of grid fluctuations while ensuring reliable and carbon-free power generation.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.1
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• pp.98-106
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• 2007

Statement of problem: Current tendencies of the implant macrodesign are tapered shapes for improved primary stability, but there are lack of studies regarding the relationship between the implant macrodesign and primary stability. Purpose: The purpose is to investigate the effect of implant macrodesign on the implant primary stability by way of resonance frequency analysis in the bovine rib bones with different kinds of quality. Material and method: Fifty implants of 6 different kinds from two Korean implant systems were used for the test. Bovine rib bones were cut into one hundred pieces with the length of 5 cm. Among them forty pieces of rib bones with similar qualities were again selected. For the experimental group 1, the thickness of cortical part was measured and 20 pieces of rib bones with the mean thickness of 1.0mm were selected for implant placement. For the experimental group 2, the cortical parts of the remaining 20 pieces of rib bones were totally removed and then implants were placed on the pure cancellous bone according to the surgical manual. After placement of all implants, the implant stability quotient(ISQ) was measured by three times, and its statistical analysis was done. Results: There are statistically significant differences in ISQ values among 4 different kinds of Avana system implants in the experimental group 2. For the experimental group 1, Avana system implants showed significantly different ISQ values, but when differences in the thickness of cortical parts were statistically considered, did not show any significant differences in ISQ values. Among Oneplant system implants, there are no significant differences in ISQ values for the experimental group 2 as well as for the experimental group 1. Conclusion: Within the limits of this study, bone quality and implant design have some influences on the primary stability of implants. Especially in the bone of poor quality, tapered shape of implants are more favorable for the primary stability of implants.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1356-1360
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• 2001

A number of calibration methods are described in ISO 16063 (revision of ISO 5347) and they may be used for special purposes. However, the use of a laser interferometer is recommended for primary calibration. This paper introduces the primary vibration calibration by measuring displacement amplitude and frequency using laser interferometry.