• Magazine of the Korean Society of Agricultural Engineers
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• v.23 no.3
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• pp.78-87
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• 1981

This study was attempted to get dimensionless unit hydrograph by linear model which can be used to the estimation of flood for the development of Agricultural water resources and laid emphasis on the application of dimensionless unit hydrographs for the ungaged watersheds by applying linear model. The results summarized through this study are as follows. 1.Peak discharge is found to be Qp= CAR (C =0. 895A-o.145) having high significance between peak discharge, Qp and effective rainfall, R within the range of small watershed area, 84 to 470km2. consequently, linearity was acknowledged between rainfall and runoff. Reasonability is confirmed for the derivation of dimensionless unit hydrograph by linear model. 2.Through mathematical analysis, formula for the derivation of dimensionless unit hydrograph was derived. qp--p=(tp--t)n-1[e-(n-1)](tp--t-1) 3.Moment method was used for the evaluation of storage constant, K and shape parameter, n for the derivation of dimensionless unit hydrograph. Storage constant, K is more closely related with the such watershed characteristics as length of main stream and slopes. On the other hand, the shape parameter, n was derived with such watershed characteristics as watershed area, river length, centroid distance of the basin and slopes. 4.Time to peak discharge, Tp could be expressed as Tp=1. 25 (√s/L)0.76 having a high significance. 5.Dimensionless unit hydrographs by linear model stood more closely to the observe dimensionless unit hydrographs On the contrary, dimensionless unit hydrographs by S.C. S. method has much difference in comparison with linear model at the falling limb of hydrographs. 6.Relative errors in the q/qp at the point of 0.8 and 1.2 for the dimensionles ratio by linear model and S. C. S. method showed to be 2.41, 1.57 and 4.0, 3.19 percent respectively to the q/qp of observed dimensionless unit hydrographs. 7.Derivation of dimensionless unit hydrograph by linear model can be accomplished by linking the two empirical formulars for storage constant, K, and shape parameter, n with derivation formular for dimensionless unit hydrograph for the ungaged small watersheds.

• Journal of the Korean Wood Science and Technology
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• v.25 no.4
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• pp.99-107
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• 1997

This study was executed to test the possibility of replacement for domestic Japanese larch(Larix leptolepis) for hardwoods and to acquire the information about the effects of drying temperature on internal temperature, moisture content and drying defects. In high-temperature drying, internal temperature increased rapidly to boiling point, immediately after that point the internal temperature rising rate was reduced. In the case of drying at temperature of $125^{\circ}C$, internal temperature could reach at boiling point in a very short time. Moisture content in high-temperature drying showed constant drying rate period and first period of falling rate drying together in 4 hours since experiment begun. There was no strong correlation between initial moisture content and final moisture content. Average drying rate at $115^{\circ}C$, $120^{\circ}C$ and $125^{\circ}C$ was 1.42%/hr, 1.88%/hr and 2.02%/hr, respectively; the case of drying temperature of $125^{\circ}C$ showed most rapid drying rate. Drying rate of $125^{\circ}C$ was so rapid that it showed more severe shrinkage, bow, collapse, end check, and internal check development than in other drying conditions. The result of this study showed the strong possibility of high-temperature drying for Japanese larch, and to dry Japanese larch optimally, dry bulb temperature should not exceed $120^{\circ}C$.

• Cross-Cultural Studies
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• v.25
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• pp.237-265
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• 2011

This thesis is to argue what is the meaning of the expression of cherry blossoms appearing in "Genjimonogatari(源氏物語)" in relation with the structure of Monogatari after checking each example. First we reviewed some examples of the works before "Genjimonogatari", and clarified that cherry blossoms were used as metaphorical expressions of a beautiful woman in waka(和歌), and that at the same time cherry blossoms functioned as the symbol of futility, anxiety together with beauty. Especially in "Kokinshu(古今集)" we identified that there increased the examples where the combination of the expression as falling cherry blossoms, and fog and cherry blossoms was done. In "Genjimonogatari" we examined the examples of cherry blossoms of Chapter 1, Chapter 2, and clarified that Murasakinoue(紫の上) was a woman with an ideal character in looks and inner personality through the diverse viewpoints of characters. In Monogatari of Kashiwagi(柏木) of Chapter 2, the scene where he peeped Onnasannomiya(女三宮) was composed by the combination of cherry blossoms and fog, and we pointed out that we could feel the anxiety, ominousness of the love of the couple through this scene. And the composition of these scenes was also repeated in Monogatari of Chapter 3, and we discussed through these examples that the figurative expressions of cherry blossoms were used about the object of the love not to be realized. Next, we checked that Yugiri(夕霧) who had observed Kashiwagi's love toward Onnasannomiya gave a figurative expression of Kashiwagi's wife Ochibanomiya(落葉の宮) as cherry blossoms. Although Genji(源氏) realized Onnasannomiya's immaturity, Kashiwagi compared her to "cherry blossoms", and Yoogiri compared the woman whom Kashiwagi recognized as "Ochiba(落葉)" to "cherry blossoms", through which we have read the twisted human relation and ironical structure of Chaper 2. Finally, we checked the examples of cherry blossoms in Ooigimi(大君), Nakanokimi(中君), Ukihune(浮舟) who were Ujijujo's heroines. Ooigimi and Nakanokimi were expressed as cherry blossoms by Kaoru(?) and Nioumiya(?宮) and were disclosed as their ideal women. In contrast, Ukihune had something to do with two men with no such figurative expression, so it was pointed out that the absence of such metaphorical expression clarified that the meaning of her existence was nothing but the meaning as a mesiudo(召人).

• Journal of the Korea Society of Computer and Information
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• v.24 no.10
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• pp.1-9
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• 2019

Fighter pilots are taking 'Advanced Pilot Training' courses to perform their missions perfectly even under adverse conditions. However, there are accidents that fall due to problems with the human body's equilibrium in the acceleration of flight, falling into the 'Vertigo, Spatial disorientation' phenomenon. As such, accidents that fighters fall due to spatial disorientation frequently occur not only in Korea but also abroad. In this study, we implemented the 'Vertigo' warning function in the fighter. First, we analyzed the aircraft's mission computer and the currently implemented warning functions. And we studied the coordinate system to utilize the aircraft attitude information. Based on this, we wanted to provide a visual warning to the HUD when the fighter flies over a certain time in the inverted flight position. Implementing this feature is expected to improve pilot flight safety. In addition, based on the results of this study, we propose a method to implement warning functions through linkage with other subsystems.

• The Journal of the Korea Contents Association
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• v.21 no.3
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• pp.454-462
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• 2021

The purpose of this paper is to compare and analyze the status of ship departures by major ports in Korea. To this end, we collected necessary data from the National Statistical Office (National Statistical Portal), "Transportation·Logistics ⇨ Ship Departure Status by Port". The analysis period is 141 months from January 2009 to September 2020. The increase rate was higher in the order of Yeosu, Pyeongtaek Dangjin, Gwangyang, Busan, Incheon and Ulsan. In the analysis of the rate of change, Yeosu showed an uptrend while other ports showed a modest downtrend. In the scatter analysis, the total ship departure shows a high degree of synchronization with other ports except Yeosu. As a result of the empirical analysis, the recent trend of ship departures is slowly falling below 0%, and the current movement is expected to continue for the time being. As the southern logistics of China and ASEAN and northern logistics of Eurasia become active, the role of major ports is expected to expand further. It is necessary to develop a differentiated logistics service for each port and find an efficient way to increase the volume of goods by deriving factors for improving logistics.

• Physical Therapy Korea
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• v.28 no.2
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• pp.123-131
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• 2021

Background: Only 2% of falls in older adults result in serious injuries (i.e., hip fracture). Therefore, it is important to differentiate injurious versus non-injurious falls, which is critical to develop effective interventions for injury prevention. Objects: The purpose of this study was to a. extract the best features of surface electromyography (sEMG) for classification of injurious falls, and b. find a best model provided by data mining techniques using the extracted features. Methods: Twenty young adults self-initiated falls and landed sideways. Falling trials were consisted of three initial fall directions (forward, sideways, or backward) and three knee positions at the time of hip impact (the impacting-side knee contacted the other knee ("knee together") or the mat ("knee on mat"), or neither the other knee nor the mat was contacted by the impacting-side knee ("free knee"). Falls involved "backward initial fall direction" or "free knee" were defined as "injurious falls" as suggested from previous studies. Nine features were extracted from sEMG signals of four hip muscles during a fall, including integral of absolute value (IAV), Wilson amplitude (WAMP), zero crossing (ZC), number of turns (NT), mean of amplitude (MA), root mean square (RMS), average amplitude change (AAC), difference absolute standard deviation value (DASDV). The decision tree and support vector machine (SVM) were used to classify the injurious falls. Results: For the initial fall direction, accuracy of the best model (SVM with a DASDV) was 48%. For the knee position, accuracy of the best model (SVM with an AAC) was 49%. Furthermore, there was no model that has sensitivity and specificity of 80% or greater. Conclusion: Our results suggest that the classification model built upon the sEMG features of the four hip muscles are not effective to classify injurious falls. Future studies should consider other data mining techniques with different muscles.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.21-29
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• 2023

Purpose : Using a smartphone while walking districts attention and increases the risk of losing balance or falling. Ankle instability is caused by decreased muscle strength and decreased neuromuscular ability leading to postural control problems. Dual tasks increases the risk of falls by reducing postural control in adults with ankle instability. This study aimed to investigate the effect of performing a dual task on balance and muscle activity in adults with ankle instability using a smartphone. Methods : Forty-nine individuals with ankle instability participated in this study. A game of finding the wrong picture was performed using a smartphone in the dual task, and only looking at the blank screen of a smartphone was evaluated in the single task. The participants randomly performed single and dual task to evalutate balance and muscle atcitivy. Balance was evaluated using the Biodex balance system (BBS), and muscle activity was evaluated using surface EMG. Muscle activity of the gastrocnemius and tibialis anterior was measured at the same time as balance. Results : The results of this study showed that overall, anteior/posterior, and medial/lateral balance indices all showed significant differences when performing the dual task compared with those during the single task (p<.05). The muscle activity results showed a significant difference compared with that of the gastronemius muscle on the nondominant side during the dual task (p>.05). Conclusion : The results of this study showed that maintaining balance is more difficult when performing the dual task than during the single task, and only the muscle activity of the nondominant gastrocnemius muscle decreased. The dual task causes a decrease in concentration for postural control, which negatively affects postural stability. Individuals with ankle ankle instability should refrain from performing dual tasks, such as using smartphones, to prevent ankle damage.

• Journal of the Korean Society of Safety
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• v.38 no.3
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• pp.10-19
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• 2023

Fall accidents account for the highest accident fatality rate in the construction industry. In addition, wearing and using a safety belt is the most realistic and important preventive measure to reduce fall accidents. Safety belts are protective devices worn by individual workers; they prevent workers from falling and allow for time to rescue the workers. However, the legal standards for safety belts only stipulate the materials, specifications, and strength of parts; there is no provision for an auxiliary rope fixing method to fix the safety belts safely. Due to this reason, workers in industrial sites arbitrarily fix and use the auxiliary rope. Currently, the most used method to fix the auxiliary rope is to tie a knot, which significantly lowers the strength of the material compared to the standard strength. Moreover, many construction sites are located outdoors, so the strength of the materials used in the auxiliary rope is inevitably reduced due to various external environmental conditions. Therefore, to solve this problem, this study was conducted to evaluate the strength of the material of the auxiliary rope for fixing the safety belt and the knot-tying method for the auxiliary rope. In this study, the exposure conditions for the effects of temperature and moisture were set to reflect the characteristics of the construction industry. The results of this study are expected to be used for standards establishment and the safe use of the auxiliary rope for safety belts in actual field applications.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.250-256
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• 2009

This paper presents a robotic tower-crane system using encoder and gyroscope sensors as path tracking devices. Tower crane work is often associated with falling accidents and industrial disasters. Such problems often incur a loss of time and money for the contractor. For this reason, many studies have been done on an automatic tower crane. As a part of 5-year 23-million-dollar research project in Korea, we are developing a robotic tower crane which aims to improve the safety level and productivity. We selected a luffing tower crane, which is commonly used in urban construction projects today, as a platform for the robotic tower crane system. This system comprises two modules: the automated path planning module and the path tracking module. The automated path planning system uses the 3D Cartesian coordinates. When the robotic tower crane lifts construction material, the algorithm creates a line, which represents a lifting path, in virtual space. This algorithm seeks and generates the best route to lift construction material while avoiding known obstacles from real construction site. The path tracking system detects the location of a lifted material in terms of the 3D coordinate values using various types of sensors including adopts encoder and gyroscope sensors. We are testing various sensors as a candidate for the path tracking device. This specific study focuses on how to employ encoder and gyroscope sensors in the robotic crane These sensors measure a movement and rotary motion of the robotic tower crane. Finally, the movement of the robotic tower crane is displayed in a virtual space that synthesizes the data from two modules: the automatically planned path and the tracked paths. We are currently field-testing the feasibility of the proposed system using an actual tower crane. In the next step, the robotic tower crane will be applied to actual construction sites with a following analysis of the crane's productivity in order to ascertain its economic efficiency.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.353-360
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• 2022

Due to the dense and complicated working environment, the construction industry is susceptible to many accidents. Worker's fall is a severe problem at the construction site, including falling into holes or openings because of the inadequate coverings as per the safety rules. During the construction or demolition of a building, openings and holes are formed in the floors and roofs. Many workers neglect to cover openings for ease of work while being aware of the risks of holes, openings, and gaps at heights. However, there are safety rules for worker safety; the holes and openings must be covered to prevent falls. The safety inspector typically examines it by visiting the construction site, which is time-consuming and requires safety manager efforts. Therefore, this study presented a worker-driven approach (the worker is involved in the reporting process) to facilitate safety managers by developing integrated computer vision and inertia sensors-based mobile applications to identify openings. The TensorFlow framework is used to design Convolutional Neural Network (CNN); the designed CNN is trained on a custom dataset for binary class openings and covered and deployed on an android smartphone. When an application captures an image, the device also extracts the accelerometer values to determine the inclination in parallel with the classification task of the device to predict the final output as floor (openings/ covered), wall (openings/covered), and roof (openings / covered). The proposed worker-driven approach will be extended with other case scenarios at the construction site.