• The Korean Journal of Ecology
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• v.14 no.4
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• pp.415-433
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• 1991

Seasonal variation in size and number of floral structures was examined in two massachusetts populations of chelidonium major, a self-compatible herb. All floral charcters except for anther number per flower declind significantly during a 3 week period. However, temporal patterns were not identical among characters or between popolations. The result indicate that floral characters varied in conjunction with flower diameter,but that the pattern of changes in floral characters in response to environments may not be easy to predict. Principal components analysis was conducted to environments may not be easy to predict. principal compenents analysis was conducted tl identify the functional relationship among floral male function, and female function, respectively, perhaps reflecting the functional distinction of floral characters. Based on this pattern, the relative allocation to sexual structures within flowers was examined: male allocation was relatively greater than female allocation eary or in the middle of flowering season, depending upon populations. Temporalvariation in relative allocation within flowers was not independent of seed tield components:; different combinations of the size and number of floral characters were correlated with different seed yield components, for example, either seed size or number per fruit, during a season. in particular, allocations to attractive and male structures were highly correlated with mean seed weight only earlier in the season. These result provide some evidence that flowering phenolgy is an important comportant to be considered in the study of sexual allocation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.190-193
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• 2005

The air filter in engine intake system filters the dirt in the breathing air but also it attenuates the noise although the phenomenon has been regarded negligible. For the analysis of the acoustical performance of air filter, an acoustical model is suggested in this paper. The air filter consists of a porous filter element, which catches the particulate dirt, and a plastic filter box, which supports the filter element. Fibrous structure of the filter element is modeled as a micro-perforated panel using the flow resistivity and porosity. The pleated geometry of the filter element is modeled as two coupled ducts and a mathematical model is developed for the analysis of sound propagation. The filter box Is modeled as a rigid rectangular box. By combining two models, a 4-pole transfer matrix for the air filter is derived. The transmission loss calculated using the transfer matrix of the suggested model is compared with the measured data. Reasonably good agreement is observed. The result can be improved by considering the visco-thermal effect in modeling, in particular at a frequency range near the troughs of TL curve.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.1033-1039
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• 2006

To overcome the drawback of currently available curved beam theories having non-symmetric thin-walled cross sections, a curved beam theory based on centroid-shear center formulation is presented for the spatially coupled free vibration and elastic analyses. For this, the elastic strain and kinetic energies considering the thickness-curvature effect and the rotary inertia of curved beam are derived by degenerating the energies of the elastic continuum to those of curved beam. And then the equilibrium equations and the boundary conditions are consistently derived for curved beams having non-symmetric thin-walled cross section. It is emphasized that for curved beams with L- or T-shaped sections, this thin-walled curved beam theory can be easily reduced to tl1e solid beam theory by simply putting the sectional properties associated with warping to zero. In order to illustrate the validity and the accuracy of this study, FE solutions using the Hermitian curved beam elements are presented and compared with the results by previous research and ABAQUS's shell elements.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.133-135
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• 2004

As a result of the recent advances in magnetic materials, the Magnetic Amplifier(Magamp) technique is one of the reliable and cost-effective postregulation method for multiple-output power supply. This is true for high-current postregulated output since at highter output current the efficiency of linear postregulation is unacceptably low, while the complexity of more efficient switch mode postregulator is associated with a significant cost. Magamp have some advantages of higher power density, simple control circuit, good regulation, high frequency and high performance. In this paper, Operation principle of proposed approach and a performance of magamp control circuit with TL431 is described. The comparative analysis of magamp circuit and buck regulator circuit with 20W load condition is conducted. Experimental verifications on multi-output flyback converter are conducted. Simulations and experimental results show that the proposed approach is efficiency and voltage regulation of the auxiliary output is excellent.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.278-289
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• 2021

In this study, the acoustic performance of a dissipative silencer used in the ship with excellent performance compared to its size was predicted and analyzed using a numerical analysis method to reduce the pipe noise. To this end, the performance of the single expansion chamber-shaped silencer was verified using experimental and numerical analysis methods. The acoustic performance of the silencer was expressed using the Transmission Loss (TL), an indicator of its own performance, and the result was derived using the two-load method, which measured by changing the impedance at the end of the pipe. For the numerical analysis method, a general-purpose finite element analysis program was used, and the Delany-Bazley-Miki model with the flow resistivity of the sound absorbing material as an input parameter was applied. Finally, we compared the experimental and simulated results for each of the acoustic performances of the single expansion type and the dissipative silencer to confirm the consistency of the results, and predicted and analyzed the simulation results for four cases according to the properties of the sound absorbing material.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1207-1216
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• 2023

As the domestic animation industry is shrinking, it is time to actively respond to changes in new technologies and animation production methods. From 2016 to 2020, through patent information registered in the United States, China, and Korea in the field of animation technology, applicants who are the subject of technology were analyzed and technical policies and strategies pursued by applicants in each country were reviewed. China registered the most patents, so the technical activity index was high, and the US family patent size was high. As a result of positioning analysis, the U.S. market expansion influence decreased over time, China's technological activity gradually increased over time, and Korea's technological activity and family patent size decreased. Reflecting China's rise as the world's largest animation producer, Korea should also develop a policy to support animation.

• Korean Journal of Environment and Ecology
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• v.25 no.6
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• pp.878-886
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• 2011

The fish fauna and characteristic of population of Brachymystax lenok tsinlingensis at the 7 stations in the Bonghwa-gun were investigated from June 2010 to May 2011. The collected species during the survey period were 15 species belong to 7 families. Protected species by the legal were B. lenok tsinlingensis, Koreocobitis naktongensis, and Cottus koreanus. Korean endemic species were Microphy sogobio yaluensis, Coreoleuciscus splendidus, Zacco koreanus, Cobitis hankugensis, K. naktongensis, Iksookimia longicorpa, Niwaella multifasciata, Liobagrus mediadiposalis, C. koreanus, and Coreoperca herzi, which showed a ration of 66.7% in collected species. Dominant species were Z. koreanus(St. 1), B. lenok tsinlingensis(St. 3, 4, 5), and Rhynchocypris oxycephalus(St. 2, 6, 7). Length-weight relation in the population of B. lenok tsinlingensis was BW = $0.000008TL^{3.02}$, and condition factor in the population was average 0.84. Frequency analysis of total length indicated that the group 80~180 mm in total length is represented by one-year-old individuals, the group 200~300 mm by two-year-old individuals, and the group over 300 mm by three-year-old individuals. The density of population was presumed average 17 individuals per 100$m^2$ and total 4,760 individuals in the reservation for B. lenok tsinlingensis.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.261-265
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• 2014

The ${\gamma}$-ray concentration and gross-${\beta}$ activity by age group were measured in the teeth of males and females of the domestic residents. They were divided into 7 age groups from 10s to the age of 70s. The gross-${\beta}$ activity concentration was measured by using the Tennelec XLB measuring instrument filled with P10 gas (argon 90%, methane 10%). The ${\gamma}$-ray was measured through the ${\gamma}$-ray spectroscopic analytical method by using the high purity germanium (HPGe) radiation detector. The range of gross-${\beta}$ activity concentration was measured 0.089 to 0.32 Bq/kg in females and 0.13 to 0.26 Bq/kg in males. From the ${\gamma}$-ray spectroscopic analysis of the teeth, the natural radioactive isotopes of $^{40}K$, $^{208}Tl$, $^{228}Ac$ and $^{234}Th$ were detected and their measured ${\gamma}$-ray activity concentrations were found to be 20.7, 21.9, 3.88 and 5.24 Bq/kg, respectively.

• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.167-172
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• 1999

Purpose : To evaluate the detection rate of hyperacute intracerebral hemorrhage in echo planar imaging (EPI) and other MR sequences. materials and Methods : Intracerebral hemorrhage was experimentally induced in ten rats. EPI, fast spin-echo (FSE) T2 weighted images, fluid attenuated inversion recovery (FLAIR), spin-echo (SE) T1 weighted images and gradient echo (GE) T1 weight ed images of rat's brains were obtained 2 hours after onset of intracerebral hemorrhage. EPI and FSE T2 images were additionally obtained 30 min and 1 hour after onset of hemorrhage in 3 and 6 rat, repeatedly, For objective visual assessment, discrimination between the lesion and normal brain parenchyma was evaluated on various MR sequences by three radiologists. For quantitative assessment, contrast-to-noise ratio (CNR) was calculated fro hemorrhage-normal brain parenchyma. Statistical analysis was performed usning the Wilcoxon-Ranks test. Results : EPI, FLAIR, and FSE T2 images showed high signal intensity lesions. The lesion discrimination was easier on EPI than on other sequences, and also EPI showed higher signal intensity for the subjective visual assessment. In quantitative evaluation, CNR of the hemorrhagic lesion versus normal brain parenchyma were higher on EPI and FLAIR images (p<0.01). There was no difference in CNR between EPI and FLAIR (p>0.10). On MR images obtained 30 minutes and 1 hour after the onset of intracerebral hemorrhage, the lesion detection was feasible on both EPI and FSE T2 images showing high signal intensity. Conclusion : EPI showed higher detection rate as compared with other MR sequences and could be useful in early detection and evaluation of intracerebral hemorrhage.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.49-53
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• 2016

Purpose Recently, Cadmium-zinc-telluride (CZT) semiconductor myocardial SPECT (Single Photon Emission Computed Tomography) has been used myocardial scintigraphy. In this study, the performance of Semiconductor SPECT and conventional SPECT systems was compared by a comprehensive analysis of phantom SPECT images. Materials and Methods Methods: We evaluated the DSPECT CZT SEPCT (Spectrum-dynamic) and INFINA conventional (GE). Physical performance was compared on reconstructed SPECT images from a phantom. Results For count sensitivity on cardiac phantom images ($counts{\cdot}sec^{-1}{\cdot}MBq^{-1}$), DSPECT had a sensitivity of conventional SPECT. This classification was similar to that of myocardial counts normalized to injected activities from phantom images (respective mean values, $counts{\cdot}sec^{-1}{\cdot}MBq^{-1}$: 195.83 and 52.83). For central spatial resolution: DSPECT, 9.47mm; conventional SPECT, 16.90mm. For contrast-to-noise ratio on the phantom: DSPECT, 4.2; conventional SPECT, 3.6. Conclusion The performance of CZT cameras is dramatically higher than that of conventional SPECT. However, CZT cameras differ in that spatial resolution and contrast-to-noise ratio are better with conventional SPECT, whereas count sensitivity is markedly higher with the DSPECT.