• Korean Journal of Agricultural and Forest Meteorology
• /
• v.16 no.4
• /
• pp.259-266
• /
• 2014

Understanding the forest fire patterns is necessary to comprehend the stability of the forest ecosystems. Thus, researchers have suggested the simulation models to mimic the forest fire spread dynamics, which enables us to predict the forest damage in the scenarios that are difficult to be experimentally tested in laboratory scale. However, many of the models have the limitation that many of them did not consider the complicated environmental factors, such as fuel types, wind, and moisture. In this study, we suggested a simple model with the factors, especially, the geomorphological structure of the forest and two types of fuel. The two fuels correspond to susceptible tree and resistant tree with different probabilities of transferring fire. The trees were randomly distributed in simulation space at densities ranging from 0.5 (low) to 1.0 (high). The susceptible tree had higher value of the probability than the resistant tree. Based on the number of burnt trees, we then carried out the sensitivity analysis to quantify how the forest fire patterns are affected by the structure and tree density. We believe that our model can be a useful tool to explore forest fire spreading patterns.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.6
• /
• pp.67-72
• /
• 2020

Life tests are essential in reducing the catastrophic damage caused by the accidents of large machinery such as aircraft and ships. However, life tests are challenging to implement due to the high costs and time required to test the life of large machinery parts. Therefore, it is advantageous and convenient to apply accelerated life test techniques for key components to reduce costs and time. In fact, extensive research has already been conducted on these techniques. However, recently, there have been cases in which an experimental value was applied to the shape parameter of the Weibull distribution used in the reliability test, but the test time was not significantly reduced. Therefore, in this paper, the shape parameters are estimated from the probability density function of the Weibull distribution for the analysis of an accelerated life test for bladder accumulators, which are core components of military helicopters. The test time was derived based on the number of samples and confidence level by substituting it into the test time equation. Next, the accelerated life test time was calculated using the steady-state test time with an acceleration factor obtained from the Arrhenius model. The steady-state life test required approximately 15,000 H, whereas the accelerated life test time for one sample at 100 ℃ was 34% shorter than that of the steady-state life test.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.32 no.5
• /
• pp.515-525
• /
• 2014

Recently, because of increasing in downpour and typhoon, which are caused by climate changes, those sedimentation disasters, such as landslide and debris flow, have become frequent. Those sedimentation disasters take place in natural slope. In order to predict debris flow damage range within wide area, the response model is more appropriate than numerical analysis. However, to make a prediction using Random Walk Model, the regional parameters is needed to be decided, since the regional environments conditions are not always same. This random Walk Model is a probability model with easy calculation method, and simplified slope factor. The objective of this study is to calculate the optimal parameters of Random Walk Model for Umyeon mountain in Seoul, where the large debris flow has occurred in 2011. Debris flow initiation zones and sedimentation zones were extracted through field survey, aerial photograph and visual reading of debris flow before and after its occurrence via LiDAR DEM.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.1191-1195
• /
• 2006

Now days, heavy storm occur to be continue. It is hard to use before frequency based on flood discharge for decision that design water pocket structure. We need to estimation of frequency based on flood discharge on the important basin likely city or basin that damage caused by flood recurrence. In this paper flood discharge calculated by Clark watershed method and SCS synthetic unit hydrograph method about upside during each minute of among time distribution method of rainfall, Huff method choosing Bocheong Stream basin that is representative basin of International Hydrologic Project (IHP) about time distribution of rainfall that exert big effect at flood discharge estimate to research target basin because of and the result is as following. Relation between probability flood discharge that is calculated through frequency analysis about flood discharge data and rainfall - runoff that is calculated through outward flow model was assumed about $48.1{\sim}95.9%$ in the case of $55.8{\sim}104.0%$, SCS synthetic unit hydrograph method in case of Clark watershed method, and Clark watershed method has big value overly in case of than SCS synthetic unit hydrograph method in case of basin that see, but branch of except appeared little more similarly with frequency flood discharge that calculate using survey data. In the case of Critical duration, could know that change is big area of basin is decrescent. When decide time distribution type of rainfall, apply upside during most Huff 1-ST because heavy rain phenomenon of upsides appears by the most things during result 1-ST about observation recording of target area about Huff method to be method to use most in business, but maximum value of peak flood discharge appeared on Huff 3-RD too in the case of upside, SCS synthetic unit hydrograph method during Huff 3-RD incidental of this research and case of Clark watershed method. That is, in the case of Huff method, latitude is decide that it is decision method of reasonable design floods that calculate applying during all $1-ST{\sim}4-TH$.

• Fire Science and Engineering
• /
• v.18 no.4
• /
• pp.64-71
• /
• 2004

This paper describes the result of the pump room fire analysis of the nuclear power plant using CFAST fire modeling code developed by NIST. The sensitivity studies are performed over the input parameters of CFAST: the constrained or unconstrained fire, Lower Oxygen Limit (LOL), Radiative Fraction (RF), and the opening ratio of the fire doors. According to the results, a pump room fire is the ventilation-controlled fire, so it is adequate that the value of LOL is 10% which is also the default value. It is anlayzed that the Radiative Fraction does not affect the temperature of the upper gas layer. It is appeared that the integrity of the cable located at the upper layer is maintained except for the safety pump at the fire area and the Conditional Core Damage Probability (CCDP) is 9.25E-07. It seems that CCDP result is more realistic and less uncertain than that of Fire Hazard Analysis (FHA).

• Journal of Korean Institute of Industrial Engineers
• /
• v.41 no.4
• /
• pp.352-358
• /
• 2015

It is important to guarantee the safety of vehicle to minimize the damage to the driver in case of the accidents. In order to inspect and later enhance the safety of vehicle, the owner of the vehicle usually have a vehicle safety inspection. The Korea Transportation Safety Authority (KOTSA) issues the Comprehensive Performance Inspection Certificate after vehicle inspection. The certificate only specify the legal inspection criteria for safety and measured values of the safety parameters, however, as ordinary driver in lack of expert knowledge about the vehicle is difficult to understand the contents of the Certificate. Thus, in this paper, the authors try to give the information about the inspection results in easier way to understand. This information not only guarantees the owner of the vehicle to better understand the inspection results, but it also gives the opportunity to the driver to deal with the specific problem listed in the results. The methods in this paper are to transform the vehicle inspection data into the non parametric distribution to easily represent the values to the index later on. Also, example indexes are presented to the actually inspected vehicle based on the reference distribution to show the better assessment of the developed method.

• Journal of environmental and Sanitary engineering
• /
• v.19 no.3 s.53
• /
• pp.71-80
• /
• 2004

The purpose of this study was to find the relationship between osteoporosis and various factors such as general personal background, physical activity, menstruation, daily life and dietary habit. The following are the results of this study: 1. In the relationship of osteoporosis status with general personal background, the risk of osteoporosis increased with age. Active women with higher education, high income and jobs tended to have less risk of osteoporosis. Women with earlier menarche had a tendency of having thicker bone mineral density. 2. As for disease related to bone mineral density, stomach disease, thyroid, bone damage, and bad teeth conditions were significant factors affecting bone mineral density. Women with those diseases and family history of osteoporosis were more likely to have osteoporosis. 3. In relation to food intake regular diet of dairy products, anchovy, or meat showed significantly less risk of osteoporosis. 4. In relation between dietary habits and bone mineral density, unbalanced diet had statistically less probability of osteoporosis. It is important for genetically disposed women to prevent osteoporosis in advance by considering acquired factors like life-style and medication.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.6
• /
• pp.589-597
• /
• 2010

Steel structures have a higher probability of being damaged by fatigue than by other causes of deterioration. As such, their maintenance to prevent fatigue damage is essential to sustain their safety and performance during their service period. In their maintenance, the current state of their fatigue cracks must be assessed to determine appropriate reinforcement methods and the suitable time intervals of periodic inspections when fatigue cracks are detected. Determining the crack growth rate is a successful method of predicting fractures, but it requires technical knowledge on fracture mechanics and experience in numerical methods and software for finite element analysis. In this study, a fatigue crack growth test on through-thickness cracked steel plates was conducted to assess the crack growth rate without superior technical knowledge and experience. The relationship between the Crack Opening Displacement (COD) and the crack growth rate was found in relatively long fatigue cracks.

• Herbal Formula Science
• /
• v.8 no.1
• /
• pp.257-279
• /
• 2000

Allergic contact dermatitis is a common skin disease resulting from specific immunologic to topically applied various allergen. After Dinitrochlorobenzene (DNCB) secondary sensitization, the ICR mice administered Rhemanniae radix extract (RRE) was observed to ascerstain the effect of RRE on allergic contact dermatitis. Purpose of this study was to investigate contact hypersensitivity assay, abdominal skin morphologic changes. Including mast cells and cell-surface glycoconjugates. The change of interleukin 2 (IL-2) receptor (CD25R). ICAM in abdominal skin, lymph node of inguinal region, and electro microscope-morphologic changes of abdominal skin. The results of this study were as follows: 1. The contact hypersensitivity assay, the ear swelling in the RRE had lesser probability than in the ACD Group. 2. In the general morphologic change of skin, hyperplasia of keratinocytes, distribution of vasculogenesis and epidermal lymphocytes infiltration were decreased in the RRE group compared with the ACD group. In epidermal basal layer and prickle layer, cell damage was decreased in the RRE group compared with the group painted with ACD. 3. MasT-cell in dermis was decreased in the RRE group compared with the group painted with DNCB. 4. Distribution of interlukin-2 Receptior positive cell and ICAM positive cell in dermis was decreased in the RRE Group compared with the ACD group. 5. Distribution of helper T-lymphocyte and cytotoxic T-lymphocite in inguinal nodes was decreased in the RRE group, and was observed well in paracortical area and cortical cord. 6. Distribution of apoptotic cell was appeared in the RRE group compared with the ACD group, in skin, dermis. in inguinal nodes, paracortical area observed well. With above results, the restarint of immunosuppression occuring in Allergic contact dermatitis is resulted in the slow progress the effect of Allergic contact dermatitis, and it is thought that ithis fact has a series of relation with apoptosis.

• Computers and Concrete
• /
• v.15 no.5
• /
• pp.771-794
• /
• 2015

This paper proposes an innovative method for selection of measurement sets in static parameter identification of concrete or steel bridges. This method is proved as a systematic tool to address the first steps of Structural System Identification procedures by observability techniques: the selection of adequate measurement sets. The observability trees show graphically how the unknown estimates are successively calculated throughout the recursive process of the observability analysis. The observability trees can be proved as an intuitive and powerful tool for measurement selection in beam bridges that can also be applied in complex structures, such as cable-stayed bridges. Nevertheless, in these structures, the strong link among structural parameters advises to assume a set of simplifications to increase the tree intuitiveness. In addition, a set of guidelines are provided to facilitate the representation of the observability trees in this kind of structures. These guidelines are applied in bridges of growing complexity to explain how the characteristics of the geometry of the structure (e.g. deck inclination, type of pylon-deck connection, or the existence of stay cables) affect the observability trees. The importance of the observability trees is justified by a statistical analysis of measurement sets randomly selected. This study shows that, in the analyzed structure, the probability of selecting an adequate measurement set with a minimum number of measurements at random is practically negligible. Furthermore, even bigger measurement sets might not provide adequate SSI of the unknown parameters. Finally, to show the potential of the observability trees, a large-scale concrete cable-stayed bridge is also analyzed. The comparison with the number of measurements required in the literature shows again the advantages of using the proposed method.