• Analytical Science and Technology
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• v.13 no.4
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• pp.403-411
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• 2000

This study described a method of thermoluminescence dating of pottery shards using subtraction method. TL measurement was achieved using two different types of samples prepared by quartz inclusion method and fine-grain technique. Fine grains (size range: $5-10{\mu}m$) were separated by suspending grounded pottery samples into acetone solution and sedimentation quantitatively. In quartz inclusion method quartz grains in the size range of 90 to $125{\mu}m$ diameter were obtained by extracting the quartz crystals embed in the pottery shards and etching them with 1.0 M HF solutions. The archaeological dose of both the quartz and fine grains was determined from the dose calibration curves obtained from sequential irradiation of $^{137}Cs$ gamma and $^{241}Am$ alpha source to the samples and TL measurement of natural samples, in which the alpha dose of 4.60 Gy for the Packjae pottery was obtained using subtraction method. Annual alpha dose rates ($3.05{\pm}0.11$ mGy/yr.) were determined by the analysis of U, Th contents in the pottery shards and evaluation of the values with Bell's equation. Dividing the alpha dose accumulated in the pottery shards by the annual alpha dose rate, we found age of approximately $1508{\pm}80$ years B.P. (AD. ca. 492 yr.) for the Packjae pottery. It matches well with the archeological age estimate (middle of 5th century) within 10 percent uncertainty and thereby conforms the age of the pottery sample.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.49-54
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• 2003

This study was conducted to evaluate characteristics of particle composition and organic matter distribution for tidal flat sediments in the Saemankeum area. The tidal flat sediments consist of predominantly sand and a little of silt, whereas the content of clay was very low. The analyzed values of particles of tidal flat sediments were in the range of $4.60\~10.90\;{\phi}$ for mean size and $-0.1\~1.75\;{\phi}$ for sorting and $-1.0\~0.92\;{\phi}$ for skewness and $0.27\~6.75\;{\phi}$ for kurtosis. The tidal flat sediments are interpreted as representing significant effect of the environmental change due to the construction of Saemankeum embankment. The ORP was in the range of -133$\~$200 (mean 73) mV. But 24 stations of the total stations showed reduction condition, The concentration of CODs was in the range of 17.54$\~$6,176.3 mg/kg. The ratio of C/S was 0.02$\~$0.45 (mean 0.24). And the Saemankeum tidal flat sediment was a little effected by input organic pollutants from upper site area. Conclusively, conservation of the Saemankeum tidal flat sediment was requested because it is for the growing fishery and low organic matter.

• Journal of Wetlands Research
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• v.20 no.1
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• pp.27-34
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• 2018

Reproductive phenology and physiological responses of Epilobium hirsutum L. to moisture content and nutrient content of soil were analysed in order to obtain basic data for effective conservation and restoration. Epilobium hirsutum L. is a perennial plant. But Epilobium hirsutum L. grew reproductively in all moisture and nutrient gradients. Flower bud, flowers and peduncle were respectively ripened in earlier under highest moisture condition and highest nutrient condition. And, number of flowers and peduncle were more quickly increased under highest moisture condition and highest nutrient condition. Chlorophyll content was high under highest moisture condition and higher middle moisture condition. However, we found no significant difference of chlorophyll content regard to nutrient gradients. There was no difference in minimum chlorophyll fluorescence among all moisture and nutrient gradients. The photochemical efficiency values of PS II were 0.75 in all moisture gradients, and it was 0.78 in highest nutrient gradient. The chlorophyll content of Epilobium hirsutum L. increased as the moisture content increased, and the Fv/Fm value increased as the organic matter increased. Our results showed that high moisture and nutrient content of soil advance their breeding season and promote reproductive growth. It might be important basic informations for the maintenance of population and the management of habitat of Epilobium hirsutum L. an endangered plant species.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.711-719
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• 2017

Bladeless fan is becoming increasingly popular owing to its advantages, such as improved safety, easy to clean, and attractive shape. However, many people are reluctant to purchase it because of several disadvantages, such as noise and moderate wind; therefore, research on how improve wind generation without increasing the motor speed is required. This study investigates the optimization of the shape of the nozzle and nearby surface using CFD (Computational Fluid Dynamics) simulation, ANSYS fluent. The results are analyzed by ANOM (analysis of mean) and interaction analysis; therefore this study suggests the variables of affecting Coanda effect and satisfy the govern equation, the conservation of momentum. The optimal combination was found through a predictive equation. In this study, factors and levels that affect the mass flow rate were selected and experimental points were arranged using the orthogonal array table. The value of the mass flow rate was confirmed by ANSYS fluent, which is a CFD program. Through the ANOM, it was confirmed that the nozzle distance is the most influential parameter affecting the mass flow rate. Furthermore, the mass flow rate obtained from the predictive equation and the mass flow rate from the CFD correspond to the largest values. Results from this study confirmed that the mass flow rate is increased by a change in the shape, even if the motor speed did not increase.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.419-430
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• 2021

This study investigated spatiotemporal trends of sediment-related disasters in North Korea from 1960 to 2019 and post-disaster recovery cases based on a literature review and satellite images. Results showed that occurrence status of sediment-related disasters was initially externally reported in 1995 (during the Kim Jongil era); their main triggering factor was heavy summer rainfall. Furthermore, forest degradation rate was positively correlated with population density (R² = 0.4347, p = 0.02) and occurrence number of sediment-related disasters was relatively high on the west coast region, where both variables showed high values. This indicates that human activity was a major cause of forest degradation and thus, significantly affected sediment-related disasters in mountain regions. Finally, sediment- related disasters due to shallow landslides, debris flow, and slow-moving landslides were observed in undisturbed forest regions and human-impacted forest regions, including terraced fields, opencast mines, forest roads, and post-wildfire areas, via satellite image analysis. These disaster-hit areas remained mostly abandoned without any recovery works, whereas hillside erosion control work (e.g., treeplanting with terracing) or torrent erosion control work (e.g., check dam, debris flow guide bank) were implemented in certain areas. These findings can provide reference information to expand inter-Korean exchange and cooperation in forest rehabilitation and erosion control works of North Korea.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.516-529
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• 2021

Coniferous forests in the Baekdudaegan protected area are gradually losing their landscape diversity and uniqueness along with their ecological stability due to changes in vegetation composition and structures caused by various disturbance factors, such as climate change, vegetation succession, and human interference. This study provides basic data for establishing a comprehensive conservation plan for coniferous forests in the Baekdudaegan protected area. We classified the vegetation unit types using the Zurich-Montpellier School of Phytosociology and two-way indicator species analysis methods and analyzed the species diversity and structural characteristics based on the vegetation information of 755 stands collected in the natural resources change survey of the Baekdudaegan mountains (2016 to 2020) by the Korea Forest Service. Therefore, the vegetation of the coniferous forests of theBaekdudaegan protected area was classified into 15 types under the vegetation unit hierarchy of two community groups, four communities, seven sub-communities, and 14 variants. Furthermore, we compared the total coverage among vegetation types, importance values, constancy classes, life-forms, and diversity indices. Additionally, the average total coverage and number of species per 100 m² of all coniferous forests were 232% and 21 species, respectively, with the species diversity and dominance indices averaging 1.907 and 0.222, respectively.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.610-621
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• 2021

The soil creep, primarily caused by earthquakes and torrential rainfall events, has widely occurred across the country. The Korea Forest Service attempted to quantify the soil creep susceptible areas using a discriminant value table to prevent or mitigate casualties and/or property damages in advance. With the advent of advanced computer technologies, machine learning-based classification models have been employed for managing mountainous disasters, such as landslides and debris flows. This study aims to quantify the soil creep susceptibility using several classifiers, namely the k-Nearest Neighbor (k-NN), Naive Bayes (NB), Random Forest (RF), and Support Vector Machine (SVM) models. To develop the classification models, we downscaled 292 data from 4,618 field survey data. About 70% of the selected data were used for training, with the remaining 30% used for model testing. The developed models have the classification accuracy of 0.727 for k-NN, 0.750 for NB, 0.807 for RF, and 0.750 for SVM against test datasets representing 30% of the total data. Furthermore, we estimated Cohen's Kappa index as 0.534, 0.580, 0.673, and 0.585, with AUC values of 0.872, 0.912, 0.943, and 0.834, respectively. The machine learning-based classifications for soil creep susceptibility were RF, NB, SVM, and k-NN in that order. Our findings indicate that the machine learning classifiers can provide valuable information in establishing and implementing natural disaster management plans in mountainous areas.

• Genes and Genomics
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• v.40 no.12
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• pp.1319-1329
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• 2018

SSRs were successfully isolated from the Perilla crop in our current study, and used to analyze Perilla accessions from East Asia. Analyses of the clear genetic diversity and relationship for Perilla crop still remain insufficient. In this study, 40 new simple sequence repeat (SSR) primer sets were developed from RNA sequences using transcriptome analysis. These new SSR markers were applied to analyze the diversity, relationships, and population structure among 35 accessions of the two cultivated types of Perilla crop and their weedy types. A total of 220 alleles were identified at all loci, with an average of 5.5 alleles per locus and a range between 2 and 10 alleles per locus. The MAF (major allele frequency) per locus varied from 0.229 to 0.943, with an average of 0.466. The average polymorphic information content (PIC) value was 0.603, ranging from 0.102 to 0.837. The genetic diversity (GD) ranged from 0.108 to 0.854, with an average of 0.654. Based on population structure analysis, all accessions were divided into three groups: Group I, Group II and the admixed group. This study demonstrated the utility of new SSR analysis for the study of genetic diversity and population structure among 35 Perilla accessions. The GD of each locus for accessions of cultivated var. frutescens, weedy var. frutescens, cultivated var. crispa, and weedy var. crispa were 0.415, 0.606, 0.308, and 0.480, respectively. Both weedy accessions exhibited higher GD and PIC values than their cultivated types in East Asia. The new SSR primers of Perilla species reported in this study may provide potential genetic markers for population genetics to enhance our understanding of the genetic diversity, genetic relationship and population structure of the cultivated and weedy types of P. frutescens in East Asia. In addition, new Perilla SSR primers developed from RNA-seq can be used in the future for cultivar identification, conservation of Perilla germplasm resources, genome mapping and tagging of important genes/QTLs for Perilla breeding programs.

• Korean Journal of Heritage: History & Science
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• v.50 no.3
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• pp.126-145
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• 2017

The Seokgaejae section is located along a timber access road and a driveway across Bonghwa County, North Gyeongsang Province, and Samcheog city, Gangwon Province. Its stratigraphic column shows all of the ten strata of the lower Paleozoic Taebaek Group, Joseon Supergroup. The Seokgaejae section is proved to be scientifically important. Thirty-eight domestic/international journal papers have been published on this early Paleozoic stratigraphic site, and many distinguished researchers over the world have visited the site. However, the section has never been considered to be designated as a national natural monument and was not included in the adjacent Gangwon Paleozoic National Geopark due to management or administrative issues. Although the Seokgaejae section sufficiently satisfies many of the national natural monument criteria, designation for the natural monument may not be justified because of the facts that the outcrop was artificially exposed by road construction; the chance of destruction of the outcrop is relatively few; demage on the outcrop to some extent does not impair the intrinsic value of the section; and the geomorphological/landscape value of the section is low. The application of the recently modified geological heritage assessment model to the Seokgaejae section shows very high scores on the scientific/educational, intrinsic, and functional values. Based on the improved geological heritage grade standard, the Seokgaejae section conforms to the national-level protection criteria. It is strongly recommended to manage the Seokgaejae section as a principal geosite by including it in the Gangwon Paleozoic National Geopark. This case study on the Seokgaejae section also suggests that the process of application and endorsement of a national geopark need further improvement. As well as the improvement of the system or policy related to geological heritages, further efforts of the experts in various fields of geoscience are required in order for other geological heritages not to be neglected from now on.

• Korean Journal of Heritage: History & Science
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• v.43 no.1
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• pp.4-27
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• 2010

In this article, concepts, types, and aspects of geological heritage with increasing interests as utilization as tourist attractions domestically and internationally are introduced, and the characteristics of the interpretive facilities for geological heritages in western Australia, one of the most famous geotourism areas, are considered. Based on this, the potential geotourism for the Korean Cretaceous geological heritages including dinosaur fossil sites is discussed in diverse aspects including academic values, academic and tourism infrastructures, characteristics of geotourists, systematic devices for conservation of geological heritage, economic value, and sustainability as tourist attractions. Although the Korean Cretaceous geosites are not quite competent in their scale or diversity when compared to world-class geosites, convenient access, world-class unique geographical characteristics of each geosites, and relatively cheaper travelling expenses seems to be able to give the geotourism of the South Korean Cretaceous geosites a competitive edge, attractive for international and domestic tourists seeking unique experience of 'Age of dinosaurs' for short periods with easy access from metropolitan areas and low costs. Likewise, the development of geotourism for the Korean Cretaceous geosites can revitalize the geotourism industry in South Korea, contributing to the growth in job opportunities, including students majoring in geological sciences at University.