• Journal of Surface Science and Engineering
• /
• v.56 no.1
• /
• pp.84-93
• /
• 2023

The spent nuclear fuel is burned during the planned cycle in the plant and then generates elements such as actinide series, fission products, and plutonium with a long half-life. An 'interim storage' step is needed to manage the high radioactivity and heat emitted by nuclides until permanent-disposal. In the case of Korea, there is no space to dispose of high-level radioactive waste after use, so there is a need for a period of time using interim storage. Therefore, the intensity of neutrons and gamma-ray must be determined to ensure the integrity of spent nuclear fuel during interim storage. In particular, the most important thing in spent nuclear fuel is burnup evaluation, estimation of the source term of neutrons and gamma-ray is regarded as a reference measurement of the burnup evaluation. In this study, an analysis of spent nuclear fuel was conducted by setting up a virtual fuel burnup case based on CE16×16 fuel to check the total amount and spectrum of neutron, gamma radiation produced. The correlation between BU (burnup), IE (enrichment), and CT (cooling time) will be identified through spent nuclear fuel burnup calculation. In addition, the composition of nuclide inventory, actinide and fission products can be identified.

• Journal of Astronomy and Space Sciences
• /
• v.34 no.4
• /
• pp.237-244
• /
• 2017

Magnetic flux ropes, often observed during intervals of interplanetary coronal mass ejections, have long been recognized to be critical in space weather. In this work, we focus on magnetic flux rope structure but on a much smaller scale, and not necessarily related to interplanetary coronal mass ejections. Using near-Earth solar wind advanced composition explorer (ACE) observations from 1998 to 2016, we identified a total of 309 small-scale magnetic flux ropes (SMFRs). We compared the characteristics of identified SMFR events with those of normal magnetic cloud (MC) events available from the existing literature. First, most of the MCs and SMFRs have similar values of accompanying solar wind speed and proton densities. However, the average magnetic field intensity of SMFRs is weaker (~7.4 nT) than that of MCs (~10.6 nT). Also, the average duration time and expansion speed of SMFRs are ~2.5 hr and 2.6 km/s, respectively, both of which are smaller by a factor of ~10 than those of MCs. In addition, we examined the geoeffectiveness of SMFR events by checking their correlation with magnetic storms and substorms. Based on the criteria Sym-H < -50 nT (for identification of storm occurrence) and AL < -200 nT (for identification of substorm occurrence), we found that for 88 SMFR events (corresponding to 28.5 % of the total SMFR events), substorms occurred after the impact of SMFRs, implying a possible triggering of substorms by SMFRs. In contrast, we found only two SMFRs that triggered storms. We emphasize that, based on a much larger database than used in previous studies, all these previously known features are now firmly confirmed by the current work. Accordingly, the results emphasize the significance of SMFRs from the viewpoint of possible triggering of substorms.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.4
• /
• pp.285-297
• /
• 2023

The present study aims to investigate the acoustic performance of the creative convergence classrooms in Korea used by elementary school students under the age of 9 introduced through the school space innovation project. In order to do this, acoustic performances of three creative convergence classrooms were measured. The measured acoustic parameters were background noise levels, Reverberation Time (RT), D₅₀, Speech Transmission Index (STI), and Inter-Aural Cross Correlation (IACC). Also, acoustic parameters including Transmission Loss (TL) and standardized level difference (D_nT) have been measured for the analysis of sound insulation performance of walls. In addition, the noise level was measured according to the opening conditions of doors and windows in the classroom. As a result, background noise level was measured at an average of 28.0 dB(A) to 32.8 dB(A) when the air conditioner was not operated, and the RT did not exceed 0.6 s. There were differences in IACC according to various desk layouts, and IACC values were high in the center line and the seats near the sound source. In particular, higher IACC was measured at the seats on the center line facing the source squarely. Regarding noise level in the classroom according to the opening conditions of doors and windows, the standards were exceeded when all windows, or windows and doors front onto the corridor were opened.

• Tunnel and Underground Space
• /
• v.19 no.6
• /
• pp.558-566
• /
• 2009

Time-dependent behavior is a basic mechanical property of rocks. Predicting the failure time of rock structures by analyzing the time-dependent characteristic is important and problematic. It is tried to predict the failure time of tunnel, slope & laboratory creep test specimen from measured displacement(or strain) and rate with relationship suggested by Voight($\ddot{\Omega}=A\dot{\Omega}^\alpha$, where $\Omega$ is a measurable quantity such as strain & displacement and A & $\alpha$ are constants). A & $\alpha$ are estimated through applying the nonlinear least square method to the single and double integrated Voight's equations and utilized to predict the failure time. Predicted failure time is in accordance with real one except minor error. Linear inverse rate method applied to creep strain and rate yields a poor linear correlation of data and precision of predicted failure time is not better than methods using strain and rate.

• Journal of Astronomy and Space Sciences
• /
• v.22 no.4
• /
• pp.353-362
• /
• 2005

We performed a new high-resolution spectroscopy of AG Vir for 4 nights from 25 March 2004 using the BOES (Bohyunsan Optical Echelle Spectrograph) attached to the 1.8-m reflector at Bohyunsan Optical Astronomy Observatory, and obtained a total of 59 spectra where all orbital phases are covered. To get the radial velocities of the binary system, both method of the CCF (Cross-Co..elation Function)and the BF (Broadening Function) were applied to the analysis of all the observed spectra. From these, the CCF could calculate the radial velocities of the primary star alone, while the BF could determine those of the primary and the secondary components. New absolute dimensions were deduced with the combination of our spectroscopic orbital elements ($K_1=90.5km/s$와 $K_2=258.8$) and the photometric solutions of Bell, Rainger, & Hilditch (1990): $A_1,=1.99M_\bigodot,\;M_2=0.62M_\bigodot,\;R_1=2.21R_\bigodot,\;R_2=1.36R_\bigodot,\;L_1=13.17L_\bigodot,\;and\;L_2=3.47L_\bigodot$. Our absolute parameters are larger and brighter than those derived from Bell, Rainger, & Hilditch (1990). We re-analyzed all the previous radial-velocity curves of AG Vir and, as a result, can see that its system velocity scatters largely up to ${\pm}8km/s$. However, we, at present, cannot determine this as the light-time effect due to the third body, which was suggested as a cause of the orbital period changes by Qian (2001).

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.29 no.3
• /
• pp.7-15
• /
• 2023

Purpose: This study was conducted with the aim of presenting spatial planning directions for evacuation spaces based on an analysis of the performance of horizontal evacuation during the early stages of fire incidents in a geriatric hospital. Methods: Based on a review of previous studies, the research model was designed by establishing occupancy conditions, evacuation, and fire scenarios. The analysis model was developed by considering vulnerable areas in terms of evacuation movement and analyzing the results of evacuation performance. Furthermore, the study analyzed the improvement in evacuation performance by arranging refuge areas. Results: The results of the study are as follows. Firstly, vulnerability spots were identified in terms of evacuation performance by schematizing Required Safe Egress Time, Available Safe Egress Time, and their differences. Secondly, the Required Safe Egress Time in the adjacent public spaces along the escape routes of occupants was found to be higher compared to the Available Safe Egress Time. Thirdly, the results of the correlation analysis between the difference in Available Safe Egress Time and Required Safe Egress Time during the early stages of a fire, as well as their constituent factors, demonstrated that user congestion is a more significant factor in compromising evacuation safety than the physical changes in the fire condition. Fourthly, the analysis of evacuation time was conducted by designating refuge areas where occupants can evacuate within a sufficient timeframe. This led to a decrease in the Required Safe Egress Time. Implications: This study is expected to be used as data on the direction of evacuation space planning to improve the evacuation performance of Geriatric Hospital.

• Korean Institute of Interior Design Journal
• /
• no.16
• /
• pp.98-105
• /
• 1998

Today the worship of entertainment i.e television has created a situation of diminshing monumental environments with increasing leisure time. Let us examine retrospectively the characteristics of the Urban theater Architecture. Two aspects would stand out as Theater Architecture gets closer to the urban tradition or trends to make a part of a city come to life. One aspect is an introvert purity. The other is an extrovert organic structure on the edge of connecting urban scenary with anything hoping to find the renewable element which could be revived eternally in architecture.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.8
• /
• pp.62-70
• /
• 1997

In this paper, we presetn a new method to display 3-D image modelled as a sum of 2-D sliced images by expanding the concept of the conventional 2-D optical correlator based on spatial matched filtr to the 3-D region. It is hsown that a arbitrary image can be constructed by an array of the correlation-peaks between pixel-to-pixel and propose the systhesis precedure of 3-D spatial-matched-fjilter using fresnel diffraction equation to display 3-D image in space. It is also shown that the quantization problem is severe when the systehsised filter function is displayed on the conventional LC-SLM. To overcome this problem, anonlinear quantizaton method using the sigmoid function is suggested, and this method can reduce the bias and the loss of high spatial-frequency information, and improve the diffraction efficiency. Finally, the suggested method is tested by computer simulation and then approved by some optical experiments with the conventional LC-SLM.

• Journal of Environmental Science International
• /
• v.14 no.11
• /
• pp.1035-1047
• /
• 2005

By using hourly $NO_2$ concentration data$(1998\~2000)$ at the Busan Metropolitan City air qualify monitoring sites, characteristics of daily mean value of $NO_2$ concentration was discussed in space and time. The correlation between $NO_2$ concentration and other relating air pollutants was analyzed by using SAS program and meteorological parameters as well. After choosing representative 4 areas, this study used hourly concentration data$(1998\~2000)$ from air quality monitoring sites on $NO_2,\;NO,\;O_3,\;CO,\;SO_2\;and\;PM_{10}$. Typical metropolitan characteristics of two peaks in a day was shown in the variation of $NO_2$ concentration of Busan city.

• Korean Institute of Interior Design Journal
• /
• no.17
• /
• pp.187-195
• /
• 1998

The purpose of this study is to analyze the characteristics of exhibition circulation which is caused by behavioral factors of visitor's movement and spatial factors in museums. It looks into the factors under the influence with the visitor's movement. The consideration of exhibition circulation may be classified into 2 categories. one is spatial factors which can make a exhibition circulation according to the extent of exhibition space display density position of exit display style and display secenario. and another is the behavioral factors of visitor's movement according to the time speed proportion of appreciation and visiting rate. The method of analysis is statistics of investigation by following after visitors. Through this data we found out that there are correlation with two categories. Therefore each factor that makes an exhibition circulation with organic relevancy have influence on the visitor's movement directly. So appropriate to the planning of each factor can offer visitors to more effective environment of exhibition.