• Journal of Forest and Environmental Science
• /
• v.34 no.2
• /
• pp.196-198
• /
• 2018

This study aimed to evaluate the effectiveness of jellyfish chips in promoting the survival and growth of Pinus thunbergii seedlings in a coastal area based on a five-year field investigation from 2012 to 2016. Seedling survival rate was significantly higher in the treatment (96%) than in the control (75%) group in 2012. Furthermore, the height of five-year-old seedlings after plantation in 2012 was significantly greater in the treatment (3.41 m) than in the control (2.32 m) group (t=10.151; p-value<0.01). These results revealed that jellyfish chips can improve soil condition by enhancing moisture retention during the early growth stages and supplying nutrients to the seedlings over time. Our findings indicated that jellyfish chips could be used effectively as an organic fertilizer for growing coastal disaster prevention forests.

• Wind and Structures
• /
• v.28 no.2
• /
• pp.99-110
• /
• 2019

Vortex-Induced-Vibration (VIV) is one kind of the wind-induced vibrations, which may occur in the construction and operation period of bridges. This phenomenon can bring negative effects to the traffic safety or can cause bridge fatigue damage and should be eliminated or controlled within safe amplitudes.In the current VIV studies, one available mitigation countermeasure, the horizontal flow-isolating plate, shows satisfactory performance particularly in PI shaped bridge deck type. Details of the wind tunnel test are firstly presented to give an overall description of this appendage and its control effect. Then, the computational-fluid-dynamics(CFD) method is introduced to investigate the control mechanism, using two-dimensional Large-Eddy-Simulation to reproduce the VIV process. The Reynolds number of the cases involved in this paper ranges from $1{\times}10^5$ to $3{\times}10^5$, using the width of bridge deck as reference length. A field-filter technique and detailed analysis on wall pressure are used to give an intuitive demonstration of the changes brought by the horizontal flow-isolating plate. Results show that this aerodynamic appendage is equally effective in suppressing vertical and torsional VIV, indicating inspiring application prospect in similar PI shaped bridge decks.

• International Journal of High-Rise Buildings
• /
• v.9 no.4
• /
• pp.307-314
• /
• 2020

High-rise buildings with vertical setback are widely used in practice. From the field investigation of the past earthquakes, it was found that such kind of vertically irregular high-rise building structures easily suffer severe damage during strong earthquakes. This paper presents an extensive study on the earthquake responses of moment-resisting frame structures (MFS) popularly applied in high-rise buildings with vertical setback. Four groups of MFS are designed, including three groups of structures with vertical setback and one group of structures with the lateral stiffness varying along the building height but without vertical setback. The numerical models of the structures are established, and the time history analysis of the structures under different levels of earthquakes is conducted. The earthquake responses of the structures are compared. The influence of the ratio between the horizontal setback dimension and the previous plan dimension, the eccentricity of setback, and the position where the setback occurs on the seismic performance of structures is studied. The rationality of the provisions for the structures with vertical setback specified in the current design codes is checked by the findings from this study.

• Journal of Korean Society of Disaster and Security
• /
• v.16 no.1
• /
• pp.23-35
• /
• 2023

Recently, the damage caused by natural disasters such as typhoons and localized torrential rains has been increasing rapidly. The Ministry of the Interior and Safety enacted a ｢law on safety management of small sized infrastructures｣ and local governments have to register small sized infrastructures with the National Disaster and Safety Management System (NDMS) until March 31st every year. Recently, each local government has ordered Safety inspections of small sized infrastructures and maintenance plans and six types of facilities, including small streams, small bridges, farm roads, access roads to village, inlet weirs, and drop structures are being surveyed and digitized into a database. Each facility is being evaluated for risk, and for those deemed hazardous, maintenance plans are being developed. However, since the risk assessment method of small sized infrastructures is not clear so that is conducted through visual investigation by field investigators, risk assessment is conducted in a subjective and ambiguous form. Therefore, this study presented a reasonable and quantitative risk assessment method by providing a quantitative evaluation indicator for small stream, which has the highest disaster risk among other small sized infrastructures, so that small sized hazard infrastructures can be selected to secure transparent evidence for improvement plans and action plans.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.42 no.4
• /
• pp.106-114
• /
• 2000

An investigation was conducted to get the basic data for establishing maintenance strategy of pipe framed greenhouses. The contents of the investigation consisted of actual state of structures, maintenance status, meteorological disaster, and corrosion characteristics of pipe framework in greenhouses. the number of greenhouses investigated was 108 in total. Most multi-span greenhouses had narrower width and lower height than the standared 1-2W greenhouse, and most of single-span greenhouses were tunnel type. In multi-span greenhouses, the size and interval of frameworks such as rafter, purline, column , and cross beam were mostly suitable, but frameworks of single-span greenhouses were mostly insufficient. After about 7 years in grounds, 8 years in joints, 10 years in bending parts. and 13 years in columns. pipe surface was mostly rusted. Most weak parts in corrosion were pipes in contact with the ground, joints, roll-up shaft pipes, and pipes close to the gutter. Almost all of the greenhouse farmers didn't pay any attention to maintenance affair in a regular interval for pipe framed grenhouses. Many greenhouses have experienced the meteorologicla diaster such as uplift of foundation, partial or complete failure by the hyphoon and/or high winds.

• Journal of the Korea Safety Management & Science
• /
• v.2 no.3
• /
• pp.89-100
• /
• 2000

About one hundred twenty thousand ($\pm$twenty thousands) people are wounded and about two thousand persons are dead from industrial accidents in Korea ［1］, Therefore, Korea is notoriously called as a haven of disaster. This study investigated the safety situation of industries and attitude of safety managers to reduce the occurrence of accidents. The period of investigation was during March through August, 1977. Two hundreds of safety managers were replied, but replies of 183 were used because some of them were inappropriately answered for the questions. Their replies were analyzed by SAS program. As a result, only three persons out of 183 managers were women, 83% of them are married, 25.1% were graduated from university, 15.2% were graduated from two-year college. Full time safety managers were only 8% of them. Safety managers who have experienced injured before their current position were 26.3%. This confirms that company allocated injured persons to a safety department. Korea also needed an educational agency like NIOSH and a punishment agency like OSHA in USA［5］. These agencies can solve a fundamental problem of safety management for small-and-medium size industries. Furthermore, a new safety management bureau for controlling these two agencies will be necessary to reduce accidents in near future.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.11a
• /
• pp.275-279
• /
• 2004

Amusement park's indispensable facilities are dependent on electrical energy. So it is very important to ensure electrical power against fire, power failure, disaster and accident. To find out present problems, investigation was carried out for emergency and standby power systems at amusement park all over the country. We research the related regulations for Electrical facilities of internal standards and NEC. As a result, we could know that there is discrepancy between the electrical regulation and the actual condition.

• Wind and Structures
• /
• v.30 no.1
• /
• pp.1-13
• /
• 2020

The loss prediction and assessment during extreme events such as wind hazards is always crucial for the group low-rise residential buildings. This paper analyses the effect of variation in building density on wind-induced loss for low-rise buildings and proposes a loss assessment method consequently. It is based on the damage matrices of the building envelope structures and the main load-bearing structure, which includes the influence factors such as structure type, preservation degree, building density, and interaction between different envelope components. Accordingly, based on field investigation and engineering experience, this study establishes a relevant building direct economic loss assessment model. Finally, the authors develop the Typhoon Disaster Management System to apply this loss assessment methodology to practice.

• Korean Journal of Agricultural Science
• /
• v.49 no.4
• /
• pp.707-717
• /
• 2022

As the variability of recent rainfall is increasing, it is becoming important to recognize the possibility of changes in the current reservoir state in advance and to inspect the stability based on accurate evaluation standards. However, the evaluation standards for the state change factors of reservoirs are still not suitable for agricultural reservoirs and thus much improvement is needed. Therefore, in this study, the evaluation criteria for state change factors specialized for small reservoirs were categorized and standards were prepared by considering factors that may cause state changes on the dam crest, upstream slope, and downstream slope of the embankment. The categorized results were configured based on the number of mentions of the precision safety inspection report on major defects in 102 reservoirs and the defect factors found in field investigations. The findings of the study indicated that the current state change standards require many revisions for excessive or unnecessary state change factors in the reservoir. Specifically, the deletion of measurement gauges not applicable to the reservoir, the addition of defects found in the reservoir, and the scope of use of the term were proposed. The results of this study can contribute to efficient system operation and management by improving the deficiencies in the system and introducing a new state change factor.

• Spatial Information Research
• /
• v.16 no.4
• /
• pp.479-488
• /
• 2008

This paper performs investigation of the state-of-the-art approaches to building extraction in terms of their sensory input data and methodologies. For the last decades, there have been many types of sensory input data introduced into the mapping science and engineering field, which are considerably diverse in aspects of spatial resolution and data processing. With the cutting-edge technology in this field, accordingly, one of the key issues in GIS is to reconstruct three -dimensional virtual models of the real world to meet the requirements occurring in spatial applications such as urban design, disaster management, and civil works. Thus, this study investigates the strengths and weaknesses of previous approaches to automating building extraction with two categories - building detection and modeling and with sensor types categorized. The findings in this study can be utilized in enhancing automation algorithms and choosing suitable sensors, so that they can be optimized for a specific purpose.