• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.31 no.3
• /
• pp.158-169
• /
• 2019

A probabilistic model that can predict the residual useful lifetime of structure is formulated by using the gamma process which is one of the stochastic processes. The formulated stochastic model can take into account both the sampling uncertainty associated with damages measured up to now and the temporal uncertainty of cumulative damage over time. A method estimating several parameters of stochastic model is additionally proposed by introducing of the least square method and the method of moments, so that the age of a structure, the operational environment, and the evolution of damage with time can be considered. Some features related to the residual useful lifetime are firstly investigated into through the sensitivity analysis on parameters under a simple setting of single damage data measured at the current age. The stochastic model are then applied to the rubble-mound breakwater straightforwardly. The parameters of gamma process can be estimated for several experimental data on the damage processes of armor rocks of rubble-mound breakwater. The expected damage levels over time, which are numerically simulated with the estimated parameters, are in very good agreement with those from the flume testing. It has been found from various numerical calculations that the probabilities exceeding the failure limit are converged to the constraint that the model must be satisfied after lasting for a long time from now. Meanwhile, the expected residual useful lifetimes evaluated from the failure probabilities are seen to be different with respect to the behavior of damage history. As the coefficient of variation of cumulative damage is becoming large, in particular, it has been shown that the expected residual useful lifetimes have significant discrepancies from those of the deterministic regression model. This is mainly due to the effect of sampling and temporal uncertainties associated with damage, by which the first time to failure tends to be widely distributed. Therefore, the stochastic model presented in this paper for predicting the residual useful lifetime of structure can properly implement the probabilistic assessment on current damage state of structure as well as take account of the temporal uncertainty of future cumulative damage.

• Korean Journal of Heritage: History & Science
• /
• v.42 no.4
• /
• pp.152-171
• /
• 2009

The Dancheong(丹靑) of the main building of Mihwangsa Buddhist Temple(美黃寺) in Haenam(海南) is the leading work of the Jeolla Dancheong style, which was created in the 18th century and has been passed down to the early modern days, and boasts its excellence and originality. On the outside, one can only see the traces of the Dancheong due to the colors that fell off and deteriorated severely. On the inside, however, the general Dancheong pattern is accompanied by the painting of 1,000 Buddhas(千佛圖), which is hardly found in other Buddhist temples, and the Arahan painting, which is truly magnificent in technique and can pass as an independent painting. The Dancheong also has unique methodological characteristics that can't be found in other Dancheong works such as the painting and attaching technique. The Dancheong inside is estimated to have been created in 1754 considering the records of "Dalmasan Mihwangsasa Daebeopdang Jungsusangryangmun(達摩山美黃寺大法堂重修上樑文)", the calligraphical writings of "Mudeungsanindanhwakya(無等山人丹?也)"and "Geonryungshipgu(乾隆十九)" left in the Jungryang, and the style characteristics reflected in the Dancheong patterns and the painting of 1,000 Buddhas. The fact that there are no traces of re-Dancheong also supports the estimation that the Dancheong was created in the absolute age of 1754. The absolute age will be the reference of deciding the chronological years of Dancheong patterns and be helpful in examining the characteristics and changes by the periods. There were certain style characteristics in Dancheong by the periods and regions. The Dancheong of Jeolla region also had its own style, which includes the tendency of finishing with two- or three-fold green belts without giving meokdanggi to the meoricho and the huge jar decoration of huigol. Treating the baetbadak of all materials, whether it's Geumdancheong or morodancheong, with lines of certain thickness and colors is another style of Jeolla Dancheong from the 18th to the 20th century. The Dancheong of the Geukrakbojeon(極樂寶殿) of Cheoneunsa Buddhist Temple and Daewoongbojeon(大雄寶殿) of Naesosa Buddhist Temple in Jeolla is especially noteworthy in that it bears similar patterns and techniques to that of the main building of Mihwangsa Buddhist Temple in addition to the characteristics mentioned above. The Dancheong of Mihwangsa Buddhist Temple must have exerted so great influences on that of the two temples that it's called "the style of Mihwangsa Buddhist Temple."When adopting a broader point of view, it can be classified as one of the Dancheong styles of Jeolla. The common icons and techniques found in the Dancheong of Mihwangsa, Cheoneunsa, and Naesosa Buddhist Temple provide some clues about the influential relationships among painters of the days. They may have been created by the painters of the same school or the painters affected by those who created the Dancheong of Mihwangsa Buddhist Temple.

• Clean Technology
• /
• v.25 no.3
• /
• pp.223-230
• /
• 2019

This research was performed to evaluate the characteristics of food waste from 5 areas in Gangwon Province, Korea and to predict the $CH_4$ gas production rate. Food wastes were sampled in July and September, 2017. The amount of methane gas generation was evaluated through the biochemical methane potential (BMP) test and a calculation method using chemical composition. Average bulk density and pH of the food wastes were in the range of $0.758{\sim}0.850g\;cm^{-3}$ and 4.29 ~ 4.75, respectively. By physical composition, vegetables were the highest with 56.43 ~ 72.81% with fruits recording 5.31 ~ 8.95%, cereals 1.60 ~ 18.73%, fish and meat 4.47 ~ 12.11%, and filtrate 1.76 ~ 3.64%. The average water content was 69.30 ~ 75.87%, and VS and ash content were 22.50 ~ 27.98% and 1.63 ~ 2.48%, respectively. In addition, $BOD_5$, $COD_{Cr}$, and $COD_{Mn}$ were in the ranges of $17,690.3{\sim}33,154.9mg\;L^{-1}$, $106,212.3{\sim}128,695.5mg\;L^{-1}$, and $51,266.1{\sim}63,426.3mg\;L^{-1}$, respectively. The NaCl content ranged from 0.81 to 1.17%. The results of elemental analysis showed that the contents of C, H, O, N, and S were 44.87 ~ 48.1%, 7.12 ~ 7.57%, 40.13 ~ 43.78%, 3.22 ~ 4.14%, and 0.00 ~ 0.02%, respectively. In a comparison of the methane production yield per VS mass of food waste, there was no significant difference between the cumulative amount (${0.303{\sim}0.354m_{CH4}}^3\;{kg_{VS}}^{-1}$) by the BMP test and the theoretical amount (${0.294{\sim}0.352m_{CH4}}^3\;{kg_{VS}}^{-1}$) calculated by chemical composition.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.17 no.3
• /
• pp.339-346
• /
• 2019

Based on the $8^{th}$ Basic Plan for Electric Power Demand and Supply, an estimation has been made for inventories and characteristics of spent fuel (SF) to be generated from existing and planned nuclear power plants. The characteristics under consideration in this study are dimensions, fuel array, $^{235}U$ enrichment, discharge burnup, and cooling time for each fuel assembly. These are essentially needed for designing a disposal facility for SFs. It appears that the anticipated quantity by the end of 2082 is about 62,500 assemblies for PWR SFs. The inventories of Westinghouse-type and Korean-type SFs were revealed to be 60% and 40%, respectively as of the end of 2018. The proportion of SFs with initial $^{235}U$ enrichment below 4.5 weight percent (wt%) was shown to be approximately 90% in total as of the end of 2018. As of 2077, more than 97% of SFs generated from Westinghouse-type nuclear reactors were shown to have cooling time of over 50 years. As of 2125, more than 98% of SFs generated from Korean-type nuclear reactors were shown to have cooling time of over 45 years. Based on these results, for the efficient design of a disposal system, it is reasonable to adopt two types of reference spent fuel. SF of KSFA with $^{235}U$ enrichment of 4.5 wt%, discharge burnup of 55 GWd/tU, and cooling time of 50 years was determined as reference fuel for Westinghouse-type SFs; SF of PLUS7 with $^{235}U$ enrichment of 4.5 wt%, discharge burnup of 55 GWd/tU, and cooling time of 45 years was determined as reference fuel for Korean-type SFs.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.21 no.1
• /
• pp.55-64
• /
• 2019

The flowering seasons can be advanced due to climate change that would cause an abnormally warm winter. Such warm winter would increase the frequency of crop damages resulted from sudden occurrences of low temperature before and after the vegetative growth stages, e.g., the period from germination to flowering. The degree and pattern of freezing damage would differ by the development stage of each individual fruit tree even in an orchard. A critical temperature, e.g., killing temperature, has been used to predict freeze damage by low-temperature conditions under the assumption that such damage would be associated with the development stage of a fruit flower bud. However, it would be challenging to apply the critical temperature to a region where spatial variation in temperature would be considerably high. In the present study, a phenological model was used to estimate major bud development stages, which would be useful for prediction of regional risks for the freeze damages. We also derived a linear function to calculate a probabilistic freeze risk in spring, which can quantitatively evaluate the risk level based solely on forecasted weather data. We calculated the dates of freeze damage occurrences and spatial risk distribution according to main production areas by applying the spring freeze risk function to apple, peach, and pear crops in 2018. It was predicted that the most extensive low-temperature associated freeze damage could have occurred on April 8. It was also found that the risk function was useful to identify the main production areas where the greatest damage to a given crop could occur. These results suggest that the freezing damage associated with the occurrence of low-temperature events could decrease providing early warning for growers to respond abnormal weather conditions for their farm.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.24 no.2
• /
• pp.208-225
• /
• 2019

To understand the mean surface circulation and surface currents in the East Sea, trajectories of surface drifters passed through the East Sea from 1991 to 2017 were analyzed. By analyzing the surface drifter trajectory data, the main paths of surface ocean currents were grouped and the variation in each main current path was investigated. The East Korea Warm Current (EKWC) heading northward separates from the coast at $36{\sim}38^{\circ}N$ and flows to the northeast until $131^{\circ}E$. In the middle (from $131^{\circ}E$ to $137^{\circ}E$) of the East Sea, the average latitude of the currents flowing eastward ranges from 36 to $40^{\circ}N$ and the currents meander with large amplitude. When the average latitude of the surface drifter paths was in the north (south) of $37.5^{\circ}N$, the meandering amplitude was about 50 (100) km. The most frequent route of surface drifters in the middle of the East Sea was the path along $37.5-38.5^{\circ}N$. The surface drifters, which were deployed off the coast of Vladivostok in the north of the East Sea, moved to the southwest along the coast and were separated from the coast to flow southeastward along the cyclonic circulation around the Japan Basin. And, then, the drifters moved to the east along $39-40^{\circ}N$. The mean surface current vector and mean speed were calculated in each lattice with $0.25^{\circ}$ grid spacing using the velocity data of surface drifters which passed through each lattice. The current variance ellipses were calculated with $0.5^{\circ}$ grid spacing. Because the path of the EKWC changes every year in the western part of the Ulleung Basin and the current paths in the Yamato Basin keep changing with many eddies, the current variance ellipses are relatively large in these region. We present a schematic map of the East Sea surface current based on the surface drifter data. The significance of this study is that the surface ocean circulation of the East Sea, which has been mainly studied by numerical model simulations and the sea surface height data obtained from satellite altimeters, was analyzed based on in-situ Lagrangian observational current data.

• Korean Journal of Heritage: History & Science
• /
• v.54 no.3
• /
• pp.228-241
• /
• 2021

Cremated archaeological bones provide crucial information to unravel the details of ancient cremation events and funeral culture. The research on cremated bones to date has been mainly focused on extracting archaeological information in Korea. Recently, the techniques of physical anthropology have been applied to obtain biological information and cremation temperatures for individuals. This study analyzed human remains excavated from Seoul Seokchon-dong Ancient Tombs and determined whether there were human cremations as well as the estimated cremation temperatures. There was no trace of fire in the pits where cremated bones were found; therefore, it is assumed that they were deposited with the artifacts. In this study, four samples were selected according to the surface color of the bones, and X-ray diffraction analysis (XRD) and Fourier-transformed infrared spectroscopy (FT-IR) were used for analysis. All four of the Seokchon-dong cremated bones were found, based on the crystallization index of X-ray diffraction analysis, to have experienced cremation above the temperature of 700℃. Infrared spectroscopy results indicated that the four bones from Seokchon-dong were cremated at temperatures above 700℃ and below 1,000℃. IR peaks were observed at 700℃, whereas no changes were found when bones experienced more than 1000℃. We assume that the cremated people in the Seokchon-dong Tombs were people of high-status because cremation at such a high temperature at that period required much effort. Here we present significant evidence of the cremation status and temperature of archaeological human bones on the basis of XRD and FT-IR, allowing for the restoration of the cremation events and funeral culture in archaeological sites.

• Journal of the Korean Wood Science and Technology
• /
• v.49 no.5
• /
• pp.399-415
• /
• 2021

This study was conducted to suggest the optimal periods for planting and felling Larix kaempferi tree by monitoring its cambial activity period. In addition, the heat summation to induce the cambial activity of Larix kaempferi was investigated. The study sites were at Mt. Worak and Mt. Midong. After selecting 5 trees at Mt. Worak and Mt. Midong, the cambium samples were collected using a mini trephor with 2 mm diameter from April 7 to October 6, 2017 at Mt. Worak, and from April 7 to September 29, 2017 at Mt. Midong. After the collected cambium samples were embedded in PEG2000, transverse thin sections with a thickness of 10 to 15 ㎛ were prepared using a microtome. One Larix kaempferi sample from each site, Mt. Worak and Mt. Midong, in which the accurate monitoring of cambial activity was impossible due to the formation of traumatic resin canal, was excluded from the study. The observation of the initiation date of cambial activity under a light microscopy revealed that 2 specimens from Mt. Worak and 3 from Mt. Midong showed the initiation on April 28. The remaining 2 specimens of Mt. Worak and 1 specimen of Mt. Midong were initiated on May 4, which was a week later than the others. The heat summation that induced the initiation of cambial activity was 196.4-271.8 at Mt. Worak and 204.7-277.3 at Mt. Midong, which was similar. The termination of cambial activity occurred between August 4 and 25 at Mt. Worak, and between August 4 and September 1 at Mt. Midong. Based on the above results, it was found that the optimal planting period for Larix kaempferi in Mt. Worak and Mt. Midong was before April, about a month before the cambium activity, and the felling period was from October when the cambial activity was completely terminated.

• The Journal of Engineering Geology
• /
• v.31 no.1
• /
• pp.103-118
• /
• 2021

For management and preservation measures of lava tube, it is studied how the blasting vibration by constructions near Geomunoreum lava tubes in Jeju affect lava tube. 11 boreholes were drilled in study area, and in-situ blasting tests were conducted by changing from 0.5 kg to 10 kg charge per delay in those boreholes. The vibration velocity, which meets the regulatory vibration criterion during daytime, was estimated as below 0.276 cm/sec by analyzing the relationship between vibration velocity and vibration level. In addition, SRE and CRE were calculated from the results of in-situ blasting tests, and k-values were shown as 130.04 in SRE, 199.71 in CRE, respectively. Also, n-values were shown as -1.717 in SRE, -1.711 in CRE, respectively. Charge per delay were assessed based on these equations, and charges per delay had ranges of 0.57~7.42 kg/delay in estimation equation of vibration velocity, 0.21~5.29 kg/delay in SRE, and 0.04~5.51 kg/delay in CRE, considering the 0.2 kine vibration criterion for cultural heritage and the 20~100 m distance from vibration source. Additionally, the relationships which meet the criteria of 0.2 kine, were calculated by combining CRE in this study with the result of previous study. Allowable charges per delay, which meet the criteria of 0.2 kine, were evaluated as 1.07 kg/delay in 50 m, 5.13 kg/delay in 100 m and 22.26 kg/delay in 200 m distances. These relationships for each vibration velocity are useful to deduce charge per delay for the ground near Geomunoreum lava tube.

• Resources Recycling
• /
• v.30 no.3
• /
• pp.47-54
• /
• 2021

Palladium present in colloidal-type plated spent catalyst solution that is used in electroless plating process has not been recovered but discharged as wastewater so far. Recyclig of paladium in colloidal-type plated spent catalyst solution is achieved with this study. This study presents the estimation of resource consumption and GHG emissions during the recycling and disposal of palladium in the plated spent catalyst solution using life cycle assessment. The reduction of resources and GHG are also estimated. Based on the palladium amount of 1 kg during disposal, the GHG emission amount was estimated to be 9.67E+03 kgCO₂eq., and the amount of resource consumption was 3.94E+01 kgSb-eq. However, GHG emission was 1.96E+03 kgCO₂eq., and the amount of resource consumption was 1.54E+01 kgSb-eq. during recycling. Considering the major substances affecting GHG emissions and amount of resource consumption, CO₂ was found to significantly affect GHG emissions, accounting for 91.42% in disposal and 98.37% in recycling. The major substance affecting the amount of resource consumption was hard coal, which accounted for 40.63% in disposal and 60.73% in recycling. Upon recycling 1 kg palladium, 8,967.17 kgCO₂eq. of greenhouse gas emission was reduced, while the resource consumption was reduced to 10.10 kg Sb-eq. In addition, the direct palladium resource reduction rate due to palladium recycling was 50%.