• 한국문헌정보학회지
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• 제57권1호
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• pp.45-68
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• 2023

본 연구의 목적은 도서관 이용에 영향을 미치는 요인을 종단적으로 분석하는 것이다. 도서관 이용의 지표 중의 하나인 대출권수의 통계적 분석을 위해 잠재성장모형과 성장혼합모형을 적용하였다. 국가도서관통계시스템에서 제공하는 2014년부터 2019년까지의 공공도서관 통계정보를 수집하고 846개 도서관을 대상으로 분석을 수행했다. 분석결과, 대출권수는 감소하는 경향이 나타났지만 감소세는 점차 완화되고 있었다. 다음으로 대출권수에 영향을 미치는 요인들을 통제한 상태에서 분석한 결과, 장서수와 독서프로그램 참여자수가 중요한 요인으로 나타났다. 마지막으로 성장혼합모형을 적용하여 분석된 5개의 계층들에서 사서수의 증가는 감소 계층에 비해 증가 계층에 속할 가능성을 높이는 것으로 나타났다.

• 국제초고층학회논문집
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• 제12권1호
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• pp.93-105
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• 2023

Seismic isolation and vibration control techniques have been developed and put into practical use by challenging researchers and engineers worldwide since the latter half of the 20th century, and after more than 40 years, they are now used in thousands of buildings, private residences, highways in many seismic areas in the world. Seismic isolation and vibration control structures can keep the structures undamaged even in a major earthquake and realize continuous occupancy. This performance has come to be recognized not only by engineers but also by ordinary people, becoming indispensable for the formation of a resilient society. However, the dynamic characteristics of seismically isolated bearings, the key elements, are highly dependent on the size effect and rate-of-loading, especially under extreme loading conditions. Therefore, confirming the actual properties and performance of these bearings with full-scale specimens under prescribed dynamic loading protocols is essential. The number of testing facilities with such capacity is still limited and even though the existing labs in the US, China, Taiwan, Italy, etc. are conducting these tests, their dynamic loading test setups are subjected to friction generated by the large vertical loads and inertial force of the heavy table which affect the accuracy of measured forces. To solve this problem, the authors have proposed a direct reaction force measuring system that can eliminate the effects of friction and inertia forces, and a seismic isolation testing facility with the proposed system (E-isolation) will be completed on March 2023 in Japan. This test facility is designed to conduct not only dynamic loading tests of seismic isolation bearings and dampers but also to perform hybrid simulations of seismically isolated structures. In this paper, design details and the realization of this system into an actual dynamic testing facility are presented and the outcomes are discussed.

• 한국안전학회지
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• 제38권4호
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• pp.8-14
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• 2023

This study presents the characteristics of short circuits (SCs) caused by excessive currents in high-voltage cables used in electric vehicles and emphasizes the need to calculate the cross-sectional areas of these cables according to the SC current. Three direct current power supplies were connected in parallel to test the SC characteristics caused by excessive currents, and a timer and a magnetic contactor were used to deliver the conduction time and SC current. A circular infrared-radiation heater was used to test the temperature-dependent SC characteristics, a thermocouple was used to measure the temperature, and a shunt resistor was used to measure the current. As the SC current increased, the fusing time of the cable decreased. Additionally, a high-voltage cable (with an area of 16 mm² ) used in electric vehicles fused when a current (approximately equal to 55 times the allowable current) flowed for 0.2 s (operating time of the protective device). When the SC current is 10 kA, the cable may fuse during the operating time of the protective device, thus creating a fire hazard. In electric vehicles, the size of the SC current increases in proportion to the capacity of the battery. Thus, the cross-sectional areas of the cables used should be calculated accordingly, and cable operations should be properly coordinated with the surrounding protective devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.17-17
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• 1998

Synchrotron radiation is produced when charged particles moving with relativistic velocities a are accelerated - for example, deflected by the bending magnets which guide the electron or p positrons in circular accelerators or storage rings. By using special focusing magnetic lattices i in the particle accelerators it is possible to make the dimensions of the particle beam very small with a hi맹 charge density which results in a light source with high b디lIiance. Synchrotron light h has important properties which make it ideal for a wide range of investigations in surface s science. The fact that the spectrum of electromagnetic radiation emitted in a bending magnet e extends in a continuum from the 얹r infra red region to hard x-rays means that it is id않I for a v variety of spectroscopic studies. Since there are no convenient lasers, or other really bright l light sources, in the vacuum ultraviolet and soft x-ray re.밍ons the development of synchrotron r radiation has enabled enormous advances to be made in this di펌C비t spectr따 re밍on. P Polarization-dependent measurements, for ex없nple ellipsometry or circular dichroism studies a are possible because the radiation has a well-defined polarization - linear in the plane of orbit w with additional right-circular, or left-circular, components for emission an생es above, or below, t the horizontal, respectively. Since the synchrotron light is emitted from a bunch of charge c circulating in a ring the light is emitted with a well-defined time structure with a short flash of l light every time a bunch passes an exit port. The time structure depends on the size of the ring a and the number and sequence of filling of the bunches. A pulsed light source enables time¬r resolved studies to be performed which provide direct information on the lifetimes and decay m modes of excited states and in addition opens up the possibility of using time of flight t techniques for spectroscopic studies. The fact that synchrotron radiation is produced in a clean u ultrahi야 vacuum environment is of gr않t importance for surce science studies. The current t비rd generation synchrotron light sources provide exceptionally high baliance and stability a and open up possibilities for experiments which would have been inconceivable only a short time ago.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.171-176
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• 1997

UO$_2$-Gd$_2$O$_3$fuel has been sintered to study the effect of powder property and sintering atmospheres on densification and microstructure. Three types of powders have been used; AUC-UO$_2$ powder and ADU-UO$_2$ powder were mixed with Gd$_2$O$_3$ Powder, and co-milled AUC-UO$_2$ and Gd$_2$O$_3$ powder. UO$_2$-(2, 5, 10)wt% Gd$_2$O$_3$pellets have been sintered at 168$0^{\circ}C$ for 4 hours in the mixture of H$_2$ and $CO_2$ gases, of which oxygen potential has been controlled by the ratio of $CO_2$ to H$_2$ gas. Densities of UO$_2$-Gd$_2$O$_3$ fuel pellets are quite dependent on powder types, and UO$_2$-Gd$_2$O$_3$ fuel using co-milled UO$_2$ powder yields the highest density. A long range homogeneity of Gd is determined by powder mixing. As the oxygen potential of sintered atmosphere increases, the sintered densities of UO$_2$-Gd$_2$O$_3$ pellets decrease but grain size increases. In addition, (U, Gd)O$_2$ solid solution becomes more homogeneous. The UO$_2$-Gd$_2$O$_3$fuel having adequate density and homogeneous microstructure can be fabricated by co-milling powder and by high oxygen potential.

• 한국산업융합학회 논문집
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• 제26권3호
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• pp.499-507
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• 2023

The core of the liquefied natural gas (LNG) carrier cargo containment system (CCS) is to store and transport LNG safely under temperatures below -163 degrees Celsius. The secondary barrier of the LNG CCS is adopted to prevent LNG leakage from CCS to the ship's hull structure. Recently, as the size of the LNG CCS increases, various studies have been conducted on the applied temperature and load ranges. The present study investigates the working condition-dependent bonding strength of the PU15 adhesives of the secondary barrier. In addition, the mechanical performance is analyzed at a cryogenic temperature of -170 degrees Celsius, and the failure surface and failure mode are investigated depending on the working condition of the bonded process. Even though the RSB and FSB-based fracture mode was confirmed, the results showed that all the tested scenarios satisfied the minimum requirement of the regulation.

• Biomolecules & Therapeutics
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• 제30권2호
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• pp.151-161
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• 2022

This study elucidates the anti-cancer potential of gallic acid (GA) as a promising therapeutic agent that exerts its effect by regulating the PI3K/Akt pathway. To prove our research rationale, we used diverse experimental methods such as cell viability assay, colony formation assay, tumor spheroid formation assay, cell cycle analysis, TUNEL assay, Western blot analysis, xenograft mouse model and histological analysis. Treatment with GA inhibited cell proliferation in dose-dependent manner as measured by cell viability assay at 48 h. GA and cisplatin (CDDP) also inhibited colony formation and tumor spheroid formation. In addition, GA and CDDP induced apoptosis, as determined by the distribution of early and late apoptotic cells and DNA fragmentation. Western blot analysis revealed that inhibition of the PI3K/Akt pathway induced upregulation of p53 (tumor suppressor protein), which in turn regulated cell cycle related proteins such as p21, p27, Cyclin D1 and E1, and intrinsic apoptotic proteins such as Bax, Bcl-2 and cleaved caspase-3. The anti-cancer effect of GA was further confirmed in an in vivo mouse model. Intraperitoneal injection with GA for 4 weeks in an A549-derived tumor xenograft model reduced the size of tumor mass. Injection of them downregulated the expression of proliferating cell nuclear antigen and p-Akt, but upregulated the expression of cleaved caspase-3 in tumor tissues. Taken together, these results indicated that GA hindered lung cancer progression by inducing cell cycle arrest and apoptosis, suggesting that GA would be a potential therapeutic agent against non-small cell lung cancer.

• Computers and Concrete
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• 제31권5호
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• pp.395-403
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• 2023

The paper investigates the effect of two parameters - sand content (SC) and grain migration during shearing - on the mechanical properties of gravel-sand mixtures. Consolidated undrained (CU) triaxial tests were carried out on eight series of mixtures containing gravel (1<d<16 mm) and sand (0.1<d<1 mm). The prepared mixtures have sand contents of 0, 10, 15, 20, 40, 54, 94 and 100%, and a relative density of 60%. The transition sand content (TSC) is experimentally defined and marks the transition from gravel-driven to sand-driven behavior. For SC<TSC, the dry density of the mixture increases with SC. This induces an increase in undrained peak strength and dilative trend. The slope and position of the critical state line (CSL) are also deeply dependent on SC. At SC=TSC, the mixtures exhibit the largest dry density and yield the highest undrained peak strength and the largest dilative trend. During shearing, large internal migration of grains was observed at the TSC, causing heterogeneity in the sample. Analysis of the CSL deduced from the final points of the triaxial tests shows that, at the TSC, failure appears to correspond to the behavior of the coarsest fraction of the soil. This fraction is located in the upper part of the sample, where the sand particles had been eliminated by suffusion. On the other hand, in the more stable materials, the CSL is consistent with the bulk grain size distribution of the soil.

• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.63-71
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• 2022

Purpose: To clarify the relationship between the diameter of the simulated bead and the Z-resolution of the tomosynthesis image. Methods: A simulated bead was placed on a 1,024×1,024×1,024-pixel base image. The diameters were set to 0.025, 0.05, 0.1, 0.2, 0.3, 0.7, 1.0, and 1.3 mm. A bead was placed at the center of the base image and projected at a simulated X-ray angle range of ±45° to obtain a projected image. A region of interest was placed at the center of the bead image and the slice sensitivity profile (SSP) was obtained by acquiring pixel values in the z-direction. The full width at half maximum of the SSP was defined as the Z-resolution and the frequency response was obtained by the 1-D Fourier transform of the SSP. Results: Z-resolution increased with increasing bead diameter. However, there was no change in Z-resolution between 0.025 and 0.1 mm. The frequency response was similar to that of the Z-resolution, with a significant difference between 0.1 and 0.2 mm diameter. Conclusions: Z-resolution is dependent on the diameter of the bead, which should be selected considering the pixel size of the tomosynthesis image.

• 한국수산과학회지
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• 제56권3호
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• pp.331-340
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• 2023

To estimate the biological reference points, suitable for fisheries management of sandfish Arctoscopus japonicas in the East Sea of Korea, we simulated the yield-per-recruit (Y/R) from age 0 to 6 (0-2,555 days). The stimulation was based on two instantaneous natural mortality conditions: size-dependent (M_t, d^-1) and constant (M_cons, d^-1); Subsequently, the biological reference points of the two mortality conditions was compared. M_t decreased from 0.0075 d^-1 to 0.0018 d^-1 depending on growth, and M_cons remained constant at 0.0011 d^-1 for all ages. Our Y/R model showed that the maximum yield of M_cons was 14 times higher than that of the M_t. The length at first capture to maximize the harvest at the F_0.1 points of the two natural mortality conditions was L_c,t=10.2 cm (TL) and L_c,cons=17 cm (TL). We concluded that M_t was more suitable for estimating M than M_cons; this is because L_c,t showed minimal difference from the current fishing regulations (11 cm, TL), and M_t reflected more biological characteristics than M_cons. We suggest that 10.2 cm and 0.8 as the suitable length at first capture and corresponding age, respectively for efficient fisheries management of sandfish.