• Magazine of the Korean Society of Agricultural Engineers
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• v.7 no.1
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• pp.861-876
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• 1965

During my stay in the Netherlands, I have studied the following, primarily in relation to the Mokpo Yong-san project which had been studied by the NEDECO for a feasibility report. 1. Unit hydrograph at Naju There are many ways to make unit hydrograph, but I want explain here to make unit hydrograph from the- actual run of curve at Naju. A discharge curve made from one rain storm depends on rainfall intensity per houre After finriing hydrograph every two hours, we will get two-hour unit hydrograph to devide each ordinate of the two-hour hydrograph by the rainfall intensity. I have used one storm from June 24 to June 26, 1963, recording a rainfall intensity of average 9. 4 mm per hour for 12 hours. If several rain gage stations had already been established in the catchment area. above Naju prior to this storm, I could have gathered accurate data on rainfall intensity throughout the catchment area. As it was, I used I the automatic rain gage record of the Mokpo I moteorological station to determine the rainfall lntensity. In order. to develop the unit ~Ydrograph at Naju, I subtracted the basic flow from the total runoff flow. I also tried to keed the difference between the calculated discharge amount and the measured discharge less than 1O~ The discharge period. of an unit graph depends on the length of the catchment area. 2. Determination of sluice dimension Acoording to principles of design presently used in our country, a one-day storm with a frequency of 20 years must be discharged in 8 hours. These design criteria are not adequate, and several dams have washed out in the past years. The design of the spillway and sluice dimensions must be based on the maximun peak discharge flowing into the reservoir to avoid crop and structure damages. The total flow into the reservoir is the summation of flow described by the Mokpo hydrograph, the basic flow from all the catchment areas and the rainfall on the reservoir area. To calculate the amount of water discharged through the sluiceCper half hour), the average head during that interval must be known. This can be calculated from the known water level outside the sluiceCdetermined by the tide) and from an estimated water level inside the reservoir at the end of each time interval. The total amount of water discharged through the sluice can be calculated from this average head, the time interval and the cross-sectional area of' the sluice. From the inflow into the .reservoir and the outflow through the sluice gates I calculated the change in the volume of water stored in the reservoir at half-hour intervals. From the stored volume of water and the known storage capacity of the reservoir, I was able to calculate the water level in the reservoir. The Calculated water level in the reservoir must be the same as the estimated water level. Mean stand tide will be adequate to use for determining the sluice dimension because spring tide is worse case and neap tide is best condition for the I result of the calculatio 3. Tidal computation for determination of the closure curve. During the construction of a dam, whether by building up of a succession of horizontael layers or by building in from both sides, the velocity of the water flowinii through the closing gapwill increase, because of the gradual decrease in the cross sectional area of the gap. 1 calculated the . velocities in the closing gap during flood and ebb for the first mentioned method of construction until the cross-sectional area has been reduced to about 25% of the original area, the change in tidal movement within the reservoir being negligible. Up to that point, the increase of the velocity is more or less hyperbolic. During the closing of the last 25 % of the gap, less water can flow out of the reservoir. This causes a rise of the mean water level of the reservoir. The difference in hydraulic head is then no longer negligible and must be taken into account. When, during the course of construction. the submerged weir become a free weir the critical flow occurs. The critical flow is that point, during either ebb or flood, at which the velocity reaches a maximum. When the dam is raised further. the velocity decreases because of the decrease\ulcorner in the height of the water above the weir. The calculation of the currents and velocities for a stage in the closure of the final gap is done in the following manner; Using an average tide with a neglible daily quantity, I estimated the water level on the pustream side of. the dam (inner water level). I determined the current through the gap for each hour by multiplying the storage area by the increment of the rise in water level. The velocity at a given moment can be determined from the calcalated current in m3/sec, and the cross-sectional area at that moment. At the same time from the difference between inner water level and tidal level (outer water level) the velocity can be calculated with the formula $h= \frac{V^2}{2g}$ and must be equal to the velocity detertnined from the current. If there is a difference in velocity, a new estimate of the inner water level must be made and entire procedure should be repeated. When the higher water level is equal to or more than 2/3 times the difference between the lower water level and the crest of the dam, we speak of a "free weir." The flow over the weir is then dependent upon the higher water level and not on the difference between high and low water levels. When the weir is "submerged", that is, the higher water level is less than 2/3 times the difference between the lower water and the crest of the dam, the difference between the high and low levels being decisive. The free weir normally occurs first during ebb, and is due to. the fact that mean level in the estuary is higher than the mean level of . the tide in building dams with barges the maximum velocity in the closing gap may not be more than 3m/sec. As the maximum velocities are higher than this limit we must use other construction methods in closing the gap. This can be done by dump-cars from each side or by using a cable way.e or by using a cable way.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.777-780
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• 2008

According to the recent tendency that the buildings in the downtown are gradually Manhattanized, the very thick massive concrete is selected as the foundation of architectures. By the way, because this mass concrete cannot be simultaneously pour in a great quantity due to the circumstance at the field, not only the questions on the unification between the concretes pour on the upper layer and the lower layer are presented but also the cracks by the internal force from the difference of hydration exothermic period are occurred, which are pointed out as the problems. Thus, this study performed Mock-up test to apply the hydration heat controlling method of massive concrete for horizontal partition pouring construction to the building sites for the purpose of securing the stability on the cracks by the internal force from the difference of hydration exothermic period on the upper layer and the lower layer of massive concrete and checked the efficiency. As the results of test, in case of setting time difference method by super retarder with 2 layers and 4 layers, the effect that temperature gaps between upper part and lower part were lowered and the possibility of crack occurrence was decreased as the peak time of the heat of hydration became delayed to the latter term could be confirmed.

• Journal of Korea Entertainment Industry Association
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• v.13 no.5
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• pp.67-72
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• 2019

Animation is a comprehensive audio-visual art, animation literature, painting, music, architecture, photography and other art forms are integrated. China's animation industry has made some achievements in the new century, but on the whole, with the globalization of China, China's animation industry has been influenced by Japan and the United States. China has a history and culture of five thousand years, with profound social deposits and cultural foundation. Of the four ancient civilizations in the world, the Chinese civilization is the only one that has survived. China has too many stories to tell. From the development history of Chinese and foreign animation, we can see that many Chinese traditional cultural elements are used for reference. Since the 1980s, Chinese animation has been on the road of national revival. Chinese animation has begun to draw close to traditional culture in terms of themes, characters and scenes, and integrate Chinese traditional cultural elements. The theme of big fish and begonia is to repay kindness by sacrificing one's own life for the sake of justice and friendship. This fearless spirit of sacrificing one's life for justice is the concentrated embodiment of the fine qualities of the Chinese nation over the past several thousand years. Kun to save chun and give up his life, chun in order to repay rather give up half of his life, and qiushui in order to help their beloved, also would rather give up all of their own. These three protagonists are very distinctive personality characteristics, are to "righteousness" and give up their most precious things. At the same time, big fish and begonia combines many traditional Chinese cultural elements to form an animated film with Chinese characteristics.

• Journal of the Korea Institute of Building Construction
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• v.18 no.2
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• pp.141-149
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• 2018

In this study, compacting, passing performance, segregation resistance and rheological properties were tested to improve the stability of fresh concrete in the production and construction of self-compacting concrete (SCC) using hollow glass powder(GB). As a result, T50 reaching time was shortened up to amount of GB $2.0kg/m^3$. The compacting according to the amount of GB was improved by ball bearing effect of GB. However, T50 reaching time was slightly increased at $4.0kg/m^3$. In the case of passing performance, the result showed that plain was Class 1, GB $0.5{\sim}2.0kg/m^3$ was Class 0, GB $4.0kg/m^3$ was Class 1. Therefore, the passing performance was improved with 'No blocking' up to amount of GB $2.0kg/m^3$. Passing performance Block step (PJ) number by J-ring method was also best at GB $1.0kg/m^3$. In the case of segregation resistance according to the amount of GB, dynamic segregation resistance was increased compared to plain regardless of the amount of GB. And static segregation resistance showed 2.5% of segregation rate at GB $1.0kg/m^3$. Therefore, it was greatly improved compared to plain (12.5%). In the case of rheology property according to the amount of GB, plastic consistency by increasing of GB content didn't show big difference. However, yield stress by increasing of GB content was decreased with GB $1.0kg/m^3$. In conclusion, GB $1.0kg/m^3$ was effective for improvement of compacting, passing performance and yield stress. Also, it will be useful for stability of SCC by improving segregation.

• Journal of Environmental Impact Assessment
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• v.30 no.3
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• pp.141-154
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• 2021

In this study, the effect of the restoration of Yaksa stream and the construction of an apartment complex by the urban renewal project in the Yaksa district of Chuncheon on air quality in the surrounding area was evaluated using computational fluid dynamics (CFD) model simulations. In orderto compare the impact of the project, wind and pollutant concentration fields were simulated using topographic data in 2011 and 2017, which stand for the periods before and after the urban renewal project, respectively. In the numerical experiments, the scenarios were set to analyze the effect of the construction of the apartment complex and the effect of stream restoration. Wind direction and wind speed data obtained from the Chuncheon Automated Synoptic Observing System (ASOS) were used as the inflow boundary conditions, and the simulation results were weighted according to the frequencies of the eight-directional inflow wind directions. The changes in wind speed and NO_X concentration distribution according to the changes in building and terrain between scenarios were compared. As a result, the concentration of NO_X emitted from the surrounding roads increased by the construction of the apartment complex, and the magnitude of the increase was reduced as the result of including the effect of stream restoration. The concentration of NO_X decreased around the restored stream, while the concentration increased significantly around the constructed apartment complex. The increase in the concentration of NO_X around the apartment complex was more pronounced in the place located in the rear of the wind direction to the apartment complex, and the effect remains up to the height of the building. In conclusion, it was confirmed that the relative arrangement of apartment complex construction and stream restoration in relation to the main wind direction of the target area was one of the major factors in determining the surrounding air quality.

• Tunnel and Underground Space
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• v.31 no.5
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• pp.374-384
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• 2021

In this study, we propose a new approach for automatic fracture detection in CT scan images of rock specimens. This approach is built on top of two-stage object detection deep learning algorithm called Faster R-CNN with a major modification of using rotated bounding box. The use of rotated bounding box plays a key role in the future work to overcome several inherent difficulties of fracture segmentation relating to the heterogeneity of uninterested background (i.e., minerals) and the variation in size and shape of fracture. Comparing to the commonly used bounding box (i.e., axis-align bounding box), rotated bounding box shows a greater adaptability to fit with the elongated shape of fracture, such that minimizing the ratio of background within the bounding box. Besides, an additional benefit of rotated bounding box is that it can provide relative information on the orientation and length of fracture without the further segmentation and measurement step. To validate the applicability of the proposed approach, we train and test our approach with a number of CT image sets of fractured granite specimens with highly heterogeneous background and other rocks such as sandstone and shale. The result demonstrates that our approach can lead to the encouraging results on fracture detection with the mean average precision (mAP) up to 0.89 and also outperform the conventional approach in terms of background-to-object ratio within the bounding box.

• The Korean Journal of Air & Space Law and Policy
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• v.31 no.2
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• pp.145-176
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• 2016

Aviation safety can be secured through regulations and policies of various areas and thorough execution of them on the field. Recently, for aviation safety management Korea is making efforts to prevent aviation accidents by taking various measures: such as selecting and promoting major strategic goals for each sector; establishing National Aviation Safety Program, including the Second Basic Plan for Aviation Policy; and improving aviation related legislations. Obstacle limitation surface is to be established and publicly notified to ensure safe take-off and landing as well as aviation safety during the circling of aircraft around airports. This study intends to review current aviation obstacle management system which was designed to make sure that buildings and structures do not exceed the height of obstacle limitation surface and identify its operating problems based on my field experience. Also, in this study, I would like to propose ways to improve the system in legal and regulatory aspects. Nowadays, due to the request of residents in the vicinity of airports, discussions and studies on aviational review are being actively carried out. Also, related ordinance and specific procedures will be established soon. However, in addition to this, I would like to propose the ways to improve shortcomings of current system caused by the lack of regulations and legislations for obstacle management. In order to execute obstacle limitation surface regulation, there has to be limits on constructing new buildings, causing real restriction for the residents living in the vicinity of airports on exercising their property rights. In this sense, it is regarded as a sensitive issue since a number of related civil complaints are filed and swift but accurate decision making is required. According to Aviation Act, currently airport operators are handling this task under the cooperation with local governments. Thus, administrative activities of local governments that have the authority to give permits for installation of buildings and structures are critically important. The law requires to carry out precise surveying of vast area and to report the outcome to the government every five years. However, there can be many problems, such as changes in the number of obstacles due to the error in the survey, or failure to apply for consultation with local governments on the exercise of construction permission. However, there is neither standards for allowable errors, preventive measures, nor penalty for the violation of appropriate procedures. As such, only follow-up measures can be taken. Nevertheless, once construction of a building is completed violating the obstacle limitation surface, practically it is difficult to take any measures, including the elimination of the building, because the owner of the building would have been following legal process for the construction by getting permit from the government. In order to address this problem, I believe penalty provision for the violation of Aviation Act needs to be added. Also, it is required to apply the same standards of allowable error stipulated in Building Act to precise surveying in the aviation field. Hence, I would like to propose the ways to improve current system in an effective manner.

• Korean Journal of Construction Engineering and Management
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• v.17 no.2
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• pp.70-79
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• 2016

The current remodeling cost estimation process is not only dependent on the historical data of new building construction, but it also has a poor linkage with risk-based estimation approach. As such, there is a high risk of falling short of initial budget. To overcome this, a risk-based estimation approach is necessary by providing a probabilistic estimation in consideration of the potential risk factors in conducting the remodeling projects. In addition, the decision-making process should be linked with the risk-based estimation results in stead of intuitive and/or experience-based estimation. This study provides a probabilistic estimation process for residential remodeling projects by developing a detailed methodology in which a step-by-step approach can be achieved. The new proposed estimation approach can help in decision-making for remodeling projects in terms of whether to proceed or not, by effectively reflecting the potential risk factors in the early stage of the project. In addition, the study can enhance the reliability of the estimation results by developing a sustainable estimation process model where a risk-based evaluation can be accomplished by setting up the cost-risk relationship database structure.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.3
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• pp.640-655
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• 2018

Recently, the construction of the urban area has been rapidly increasing, and the excavation work of the ground has been frequently performed at the upper part of the existing underground structures. Especially, when the structure is constructed after the excavation of the ground, the loading and unloading process in the ground under the excavation basement can affect the existing underground structures. Therefore, in order to maintain the stability of the existing underground structure due to the excavation of the ground, it is necessary to accurately grasp the influence of the excavation and the structure load in the adjoining part. In this study, the effect of the excavation of the ground and the new structure load on the existing tunnel was experimentally implemented and the influence of the adjacent construction on the existing tunnel was investigated. For this purpose a large testing model with 1/5 scale of the actual size was manufactured. The influence of ground excavation, width of the load due to new structure, and distance between centers of tunnel and of excavation on the existing tunnel was investigated. In this study, it was confirmed that the influence on the existing tunnel gets larger, as the excavation depth get deeper. At the same distance, it was confirmed that the tunnel displacement increased up to three times according to the increase of the building load width. That is, the load width influences the existing tunnel larger than the excavation depth. As the impact of the distance between centers of tunnel and of excavation, it was confirmed that tunnel crown displacement decreased by 48%. The result showed that a tunnel is located in the range of 1D (D: tunnel diameter) from the center of excavation, the effect of excavation is the largest.

• Korean Journal of Construction Engineering and Management
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• v.19 no.4
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• pp.93-101
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• 2018

A city is like a living organism that is born, grows and become extinct within an ecosystem. In recent years, more and more cities have been planned by designers rather than spontaneously growing over time. This planning means that if a city is not appropriately designed at the beginning, it is very hard to fix or adjust it later. A poor urban design inconveniences many people, and forces them to adjust to it. For this reason, it is important to design a city as optimally as possible at the design phase. One of the reasons why a city is not designed optimally is complexity. Previous urban design methods have attempted to resolve the complexity by using a top-down problem-solving method based on the experience and knowledge of the urban planner. However, such an approach does not have the organic characteristics of a bottom-up problem-solving method of an artificial life, based on the creation principle of the ecosystem. Therefore, in this study the general principle of artificial life, which can provide a solution to the bigger problems that accumulate as a result of the solutions to small units of problems, is adopted. This enables us to draw various urban design alternatives, and it proves that the alternatives, despite being drawn through a limited modeling method, have almost no differences from those designed by an expert, and its possibilities of future development has also been verified.