• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5C
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• pp.293-301
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• 2008

Soil profiling is one of the most important work among geotehnical engineering practice. Generally, soil profile is estimated from the observation of soil samples during subsurface exploration but such estimation also includes some experiencing aspects such as flushed water from the borehole, slime colour, boring speed and so on. In addition, since the capacity of hydraulic drill rig is significantly increased, thin layers might be easily missed. So, continuous soil profile is almost impossible over all depth to be bored from conventional subsurface exploration. While CPT or CPTu can serve continuous soil profile information over all depth generally in 5cm interval. Many charts or methods for soil profile from CPT result have been proposed during last several decades over the world. However they have not been verified in local ground condition in Korea. In this research, CPT results and soil classification results based on USCS were compiled from 17 sites over the Korea. Soil classification results by using 7 CPT soil classification charts were compared with those of USCS for the compiled database. Most proper CPT soil classification chart for Korean soil characteristics was evaluated and effective parameters for the soil classification from CPT were discussed. Finally interrelationship between CPT soil classification chart and USCS soil classification was evaluated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1C
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• pp.19-29
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• 2008

As a part of study to develop LRFD (Load and Resistance Factor Design) codes for foundation structures in Korea, reliability analyses for driven steel pipe piles are performed and the target reliability indices are selected carefully. The 58 data sets of static load tests and soil property tests conducted in the whole domestic area were collected and analyzed to determine the representative bearing capacities of the piles. The static bearing capacity formula and the Meyerhof method using N values are applied to calculate the expected design bearing capacity of the piles. The resistance bias factors were evaluated for the two static design methods by comparing the representative bearing capacities with the design values. Reliability analysis was performed by two types of advanced methods: First Order Reliability Method (FORM), and Monte Carlo Simulation (MCS) method using resistance bias factor statistics. The static bearing capacity formula exhibited relatively small variation, whereas the Meyerhof method showed relatively high inherent conservatism in the resistance bias factors. Reliability indices for safety factors in the range of 3 to 5 were evaluated respectively as 1.50~2.89 and 1.61~2.72 for both of the static bearing capacity formula and the Meyerhof method. The target reliability indices are selected as 2.0 and 2.33 for group pile case and 2.5 for single pile case, based on the reliability level of the current design practice and considering redundancy of pile group, acceptable risk level, construction quality control, and significance of individual structure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.33-40
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• 2009

The critical lag of crosswalk pedestrians is an important parameter in analyzing traffic operation at unsignalized crosswalks, however there is few research in this field in Korea. The purpose of this study is to develop a model to estimate the critical lag. Among the elements which influence the critical lag, the age of pedestrians and the length of crosswalks, which have fuzzy characteristics, and the each lag which is rejected or accepted are collected on crosswalks of which lengths range from 3.5 m to 10.5 m. The values of the critical lag range from 2.56 sec. to 5.56 sec. The age and the length are divided to the 3 fuzzy variables each, and the critical lag of each case is estimated according to Raff's technique, so a total of 9 fuzzy rules are established. Based on the rules, an ANFIS (Adaptive Neuro-Fuzzy Inference System) model to estimate the critical lag is built. The predictability of the model is evaluated comparing the observed with the estimated critical lags by the model. Statistics of $R^2$, MAE, MSE are 0.96, 0.097, 0.015 respectively. Therefore, the model is evaluated to explain the result well. During this study, it is found that the critical lag increases rapidly over the pedestrian's age of 40 years.

• Journal of Korea Entertainment Industry Association
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• v.13 no.5
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• pp.229-238
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• 2019

The aim of the research is to investigate relationship between drivers' self-control, driving behavior and driving stress. 180 people who have driver's licence and have experiences in driving in Gwangju and Jeonnam area participated for the research. The survey was conducted from 29^th April 2015 to 24^th July 2015 and data was analysed to figure out the relationship between drivers' self-control, driving behavior and driving stress. As a result, Firstly, drivers' self-control affected mistakes, violations, errors of driving behavior, and driving environment, traffic regulations, accident control, time pressure of driving stress. It showed a statistical significant difference and the higher drivers' self-control is, the lower sub construct factor of driving behavior and driving stress. Secondly, those factors of drivers' self-control, driving behavior and driving stress were correlated. The result showed the relationship between drivers' self-control, driving behavior and driving stress. It is also possible to utilize the information to prevent car accidents. Finally, it is expected to do research further by expanding the participants into multiple areas of people.

• Journal of Korean Society of Disaster and Security
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• v.16 no.3
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• pp.1-15
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• 2023

This study focuses on modeling the impact of ammonia leakage from the storage tank in a combined cycle power plant's flue gas denitrification facility. It employs accident impact assessments and diffusion models to determine the optimal scenarios for ammonia storage tank leakage accidents. The study considers the operating conditions of variables as standard conditions for predicting the extent of damage. The Taean combined cycle power plant is chosen as the target area, taking into account seasonal factors such as temperature, humidity, wind speed, atmospheric stability, and wind direction. By utilizing a Gaussian diffusion model, the concentration of ammonia gas at various locations is estimated to assess the potential extent of external damage resulting from a leak. The study reveals that in conditions of high temperature and stable atmosphere within the specified range, lower wind speeds contribute to increased damage to the human body due to ammonia diffusion.

• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.483-490
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• 2022

Floating LiDAR is a system that provides a new paradigm for wind condition observation, which is essential when creating an offshore wind farm. As it can save time and money, minimize environmental impact, and even reduce backlash from local communities, it is emerging as the industry standard. However, the design and verification of a stable platform is very important, as disturbance factors caused by fluctuations of the buoy affect the reliability of observation data. In Korea, due to the nation's late entry into the technology, a number of foreign equipment manufacturers are dominating the domestic market. The west coast of Korea is a shallow sea environment with a very large tidal difference, so strong currents repeatedly appear depending on the region, and waves of strong energy that differ by season are formed. This paper conducted a study examining buoys suitable for LiDAR operation in the waters of Korea, which have such complex environmental characteristics. In this paper, we will introduce examples of optimized design and verification of ship-type buoys, which were applied first, and derive important concepts that will serve as the basis for the development of various platforms in the future.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.3
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• pp.289-309
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• 2023

While South Korea's universal healthcare system has garnered attention in public health, the issue of inequality in healthcare service provision among different age groups has incessantly become a significant concern. The focus of this concern is primarily on essential healthcare services, encompassing fundamental aspects of healthcare such as internal medicine, family medicine, and pediatric and adolescent care. This inequality is not limited to differences among age groups (both junior and senior demographics) but also extends to potential disparities in healthcare services based on geographic location, particularly in urban and rural contexts. This paper aims to investigate disparities in primary healthcare service resources in South Korea's evolving economic landscape between 1995 and 2021. We utilize a set of inequality indices with a spatial perspective through geographic cluster analysis. The findings reveal that concerns about inequality have been amplified during various economic events, including the IMF crisis in 1999, the global financial crisis in 2008, and the COVID-19 pandemic in 2020. These years are identified as significant phases that have contributed to manifesting spatial disparities in primary healthcare provisions, with a particular emphasis on the senior-aged population rather than junior or all population groups. Our findings underscore the pressing need to address the unequal distribution of essential healthcare resources as part of preparedness for potential economic impacts, requiring a comprehensive consideration of the interconnected nature of demographic and spatial dimensions in healthcare services.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.3
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• pp.103-113
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• 2024

This study is based on the design project of 'Sun-Garden' within the Solaseado Solar Power Plant located in Solaseado, which is a New City being developed in Haenam, Jeollanam-do. The purpose of this study is to create an integrated and sustainable energyscape that harmonizes energy infrastructure with the natural environment, while supporting the city's carbon neutrality agenda. To achieve this, design principles were established by considering three key aspects. The first aspect is economic, which seeks to create multifunctional spaces that integrate nature and technology, pursuing long-term sustainability while generating additional economic value. The second aspect is natural, emphasizing the creation of planting environments that conserve and enhance ecosystems, introduce region-specific species, and maintain ecosystem services and sustainable resource use. The third aspect is landscape, offering sensory and educational experiences to visitors and functioning as a landmark that symbolizes the carbon-neutral garden city of Solaseado through the aesthetic harmony of nature and technology. Through the creation of the 'Sun-Garden,' the Solaseado Solar Power Plant exemplifies a sustainable energyscape development model that merges economic, environmental, and landscape aspects beyond the conventional energy production facility. This project is expected to provide guidelines and implications for future energy infrastructure design, contributing to global energy transition efforts.

• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.146-156
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• 2024

Background: Children who use playground facilities are exposed to potential risks due to the high concentration of heavy metals contained in the finishing materials of facilities in children's playgrounds. Objectives: The purpose of this study was to investigate the concentration of heavy metals in the finishing materials of outdoor children's playgrounds where harmful heavy metals exist in Gwangju and to conduct human risk assessment for children and adults by age to find the risks and limitations. Methods: The bottom and top layers of double-painted paint were peeled off and collected together from the finishing materials of children's play facilities such as slides, swings, and seesaws in 147 children's parks in Gwangju. Heavy metals were analyzed using ICP-OES, etc., and human risk assessment was performed using the concentrations of heavy metals. Results: Based on 1.0E-04, which requires legal regulation, CTE was found to pose a carcinogenic risk for preschool children and no carcinogenic risk for the rest of the age groups. However, RME showed that both men and women of all ages had a carcinogenic risk. For reference, when the carcinogenic risk was based on 1.0E-06, CTE was found to pose a carcinogenic risk from infants to elementary school students, and RME was found to have a carcinogenic risk in all age groups. It was judged that there is a non-carcinogenic risk if the non-carcinogenic risk exceeds 1 based on the hazard index (HI) 1. In CTE, there was no non-carcinogenic risk, and RME for preschooler males (1.49E+00) and females (1.56E+00) were found to have non-carcinogenic risk. Conclusions: This study was meaningful in that it examines the differences in the current management of heavy metals concentration standards and potential carcinogenic and non-carcinogenic risks to the human body and discusses the relationship between heavy metals and human health effects.

• Korean Journal of Heritage: History & Science
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• v.57 no.1
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• pp.38-51
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• 2024

Although the bottle gourd (Lagenaria siceraria) is a crop with a cultivation history of about 10,000 years in the Old and New Worlds, archaeological considerations on the cultivation and use of bottle gourds on the Korean Peninsula are extremely rare. Accordingly, we reviewed previous reports on bottle gourds and examined the morphological characteristics of seeds and rind fragments from the Korean Peninsula. The investigation yielded several conclusions. First, bottle gourd cultivation likely began during the Bronze Age alongside the introduction of so-called southern crops. Evidence suggests that bottle gourd remains were more prevalent during the Three-Kingdoms period, indicating its significance as a crop during the historical era. Second, bottle gourd seeds from the Three-Kingdoms period exhibit characteristics of both African and Asian subspecies, showcasing a high level of morphological diversity. Third, rind thickness indicates that bottle gourds found at the Bongseon-ri site were of varieties with large fruits. Taken together, it is concluded that the bottle gourd was introduced to the Korean Peninsula during the Bronze Age, and people cultivated a range of bottle gourd varieties during the Three-Kingdoms period.