• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.3
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• pp.74-82
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• 2003

Under the assumption that the temperature of one location is closely related to land use characteristics around that location, this study is carried out to assess the impact of urban land use patterns on air temperature. In order to investigate the relationship, GIS techniques and statistical analyses are utilized, after spatially connecting urban land use data in Seoul Metropolitan Area with atmospheric data observed at Automatic Weather Stations (AWS). The research method is as follows: (1) To find out important land use factors on temperature, simple linear regressions for a specific time period (pilot study) are conducted with urban land use characteristics, (2) To make a final model, multiple regressions are carried out with those factors and, (3) To verify that the final model could be appled to explain temperature variations beyond the period, the model is extensively used for 5 different time periods: 1999 as a whole; summer in 1999; 1998 as a whole; summer in 1998; August in 1998. The results of simple linear regression models in the pilot study show that transportation facilities and open space area are very influential on urban air temperature variations, which explain 66 and 61 percent of the variations, respectively. However, the other land use variables (residential, commercial, and mixed land use) are found to have weak or insignificant relationship to the air temperatures. Multiple linear regression with the two important variables in the pilot study is estimated, which shows that the model explains 75 percent of the variability in air temperatures with correct signs of regression coefficients. Thus, it is empirically shown that an increase in open space and a decrease in transportation facilities area can leads to the decrease in air temperature. After the final model is extensively applied to the 5 different time periods, the estimated models explain 68 ∼ 75 percent of the variations in the temperatures is significant regression coefficients for all explanatory variables. This result provides a possibility that one air temperature model for a specific time period could be a good model for other time periods near to the period. The important implications of this result to lessen high air temperature we: (1) to expand and to conserve open space and (2) to control transportation-related factors such as transportation facilities area, road pavement and traffic congestion.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.666-674
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• 2021

A selective catalyst reduction system (SCR) with an integrated bypass unit is proposed. Through simulations of the SCR, variations in flow to the catalyst due to the particular shape of the bypass shutting device in the SCR are also studied. The commercial software Ansys Fluent is used to develop the simulations. For the simulations, the catalyst of the SCR is modeled using the porous media method to reduce the calculation time and number of meshes, which is necessary because of the detailed modeling of the catalyst. Simulations are performed based on changes to the entrance angle to the catalyst and the size of the bypass shutting device. Finally, simulation results are used to compare and analyze the average velocity and uniformity of the flow to the catalyst.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.482-488
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• 2019

Leisure and business facilities have been steadily developing in Korea. Among waterborne leisure vessels and equipment, the distribution and sale of kayaks and canoes have significantly increased. Previously, (FRP) materials were primarily employed for constructing kayaks. However, owing to global warming and depletion of natural resources, the demand for non-polluting renewable energy is rapidly increasing, which has increased the demand for carbon fibers. To meet the requirements of changing social consciousness, a carbon fiber-based commercial kayak was designed in this study. Resistance analysis and structural safety were conducted by employing software tool for verifying the reliability of the proposed kayak. The pressure resistance and frictional resistance were examined in a wide range of speed. Obtained results indicate that at speeds greater than 2.6 m/s, the pressure resistance significantly increases and the total resistance also increases. Furthermore, the results corroborate that the proposed kayak structure has a adequate safety with respect to the design loads that are considered during operating conditions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.965-971
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• 2017

The primary objective of this study was to assess the energy efficiency performance of an optimized hull form capable of saving energy based on existing vessels. The bow shape of existing vessels was investigated, giving consideration to design draft and speed. Resistance performances were also assessed for existing vessels according to operating conditions. Commercial CFD codes and model test materials were used to assess effective power. An optimized hull form with minimum resistance was selected given real operating conditions. The effective horsepower of existing and optimized vessels was estimated at three speeds. Resistance performance for an optimized vessel showed a 6 % improvement in effective horsepower at design speed (12 knots) compared to existing vessels. Quasi-propulsive efficiency employed experimental data, while energy efficiency performance was analyzed based on operating days, bunker fuel oil C cost, daily fuel oil consumption and specific fuel oil consumption. Energy efficiency performance for an optimized vessel showed a gain of 30 million won per year in reduced costs at design speed (12 knots) compared to existing vessels.

• Journal of the Korean Institute of Rural Architecture
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• v.25 no.1
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• pp.1-8
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• 2023

This is a case study of private sector's development of long-term unexecuted urban parks in Pohang through a special act, which provides a guideline of 30% of land for non-park while 70% of land for park. The strategy has a lot of validity in many respects along with the urban planning sunset system, but even with the special act it would not easy to be implemented in Pohang, where the guideline has been modified to 20% for non-park, mostly multi-family housing projects while 80% for park. Thus, participation of private companies would be discouraged due to low commercial validity. Also, there would exist various risks because the project would be completed through a long-term decision-making and execution process. Thus, this study argues that it would be better for Pohang to follow the original guideline of the government for better implementation of the projects, along with preparation of a law with which the government be able to recoup excess profits when too much profits would be given to private developers. For the project implemented smoothly, it is also important to understand local housing market and fluctuating economic conditions, and to prepare various incentives for private companies. In addition, to secure publicity, guidelines on the level of publicity of the project should be prepared through negotiation by parties to prevent the project being discouraged too much.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.5
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• pp.73-81
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• 2008

The purpose of this study is to create a database of the use of landscape greenery that surrounds commercial buildings in Seoul. The method of this study was: to review preceding studies and related laws, survey areas, measure trees, and analyze the results. The 20 representative sites were specifically investigated to measure the width, direction, and environment of planting conditions. To analyze the greens adjacent to the building, the greens were divided into three types: front greenery, side greenery, and rear greenery. The study surveyed the distance from trees to adjacent buildings, and their planting conditions. The results of this study are as follows. First, 45% of the front greenery and 30% of the rear greenery were not established, but 19 of the 20 side greens were. Second, 13 of the 44 green areas adjacent to commercial buildings were under 1m in width. Most side greenery was belt -shape and unrelated to the features of the site or building. Third, the average distance from trees to buildings was 0.76m, indicating that most trees were planted too close to the buildings. Fourth, of the 30 trees utilized, the species breakdown was: 8 evergreen trees, 15 deciduous trees, and 7 shrubs. For the most part, planting patterns were similar for all species. Fifth, most sites were ill-suited to tree growth, because crown shape, planting conditions, and light conditions, etc., had not been considered. Based on these results, it is suggested that more specific, subdivided standards for planting conditions should be established. For example, building plans should include a green area that is at least one meter in width. In addition, according to the location and type(closing/opening) of the greenery adjacent to the buildings, suitable management programs and supervision protocol should be adopted.

• Journal of Navigation and Port Research
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• v.38 no.4
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• pp.335-341
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• 2014

Faced with global agenda of greenhouse abatement program including regulations and $CO_2$ emission trading scheme, shipping companies are enforced to a high level of efficiency in fuel consumption. Accordingly shipbuilding companies worldwide are required to develop fuel-efficient ships which otherwise traditionally consume a great amount of fossil fuels. In this dissertation, relevant to the improvement of fuel efficiency for commercial ships, design methodology through the numerical simulations are intensively described. This work consists of derivation of effective hydrodynamic design practice based on the application of longitudinal grooves to effectively improve the pressure distribution around ship hull. The primary objective of the present study is to improve ship resistance performance using longitudinal grooves which originate from long strips on the abdomen of humpback whale. Several groove shapes have been extensively investigated and the proposed shape efficiently controlled the variation of pressure distributions acting on the hull surface.

• Journal of KIISE
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• v.41 no.10
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• pp.859-869
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• 2014

In recent years, the obfuscation techniques are commonly exploited to protect malwares, so obfuscated malwares have become a big threat. Especially, it is extremely hard to analyze virtualization-obfuscated malwares based on unusual virtual machines, because the original program is hidden by the virtual machine as well as its semantics is mixed with the semantics of the virtual machine. To confront this threat, we suggest a framework to analyze virtualization-obfuscated programs based on the dynamic analysis. First, we extract the dynamic execution trace of the virtualization-obfuscated executables. Second, we analyze the traces by translating machine instruction sequences into the intermediate representation and extract the virtual machine architecture by constructing dynamic context flow graphs. Finally, we extract abstract semantics of the original program using the extracted virtual machine architecture. In this paper, we propose a method to extract the information of the original program from a virtualization-obfuscated program by some commercial obfuscation tools. We expect that our tool can be used to understand virtualization-obfuscated programs and integrate other program analysis techniques so that it can be applied to analysis of the semantics of original programs using the abstract semantics.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.9
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• pp.445-458
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• 2007

This article presents a novel infrastructure for large-memory database processing using commodity hardware with operating system support. We exploit inexpensive PCs and a high-speed network capable of Remote Direct Memory Access (RDMA) operations to build a new memory hierarchy between fast volatile memory and slow disk storage. The new memory hierarchy guarantees a reasonable response time, and its storage size enables us to run large-memory database systems with little performance degradation. The proposed architecture has two main components: (1) a remote memory system inside the Linux kernel to manage other computers' memory pages efficiently and (2) a remote memory pager responsible for manipulating remote read/write operations on remote memory pages. We insist that the proposed architecture is practical enough to support the rigorous demands of commercial in-memory database systems by demonstrating the performance of publicly available main-memory databases (e.g., MySQL) on our prototyped system. The experimental results show very interesting results from the TPC-C benchmark.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.13-18
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• 2015

Characteristics of restoring force for the wind-powered leisure boat was investigated using mathematical formulation and commercial computational method such as the ANSYS Workbench CFX-Mesh. The objective is to find the restoring moment and heel moment while boat is sailing in windy power. Conditions for angle of attack were given from $5^{\circ}$ to $90^{\circ}$. It is known that side force is larger in terms of angle of attack is higher, however critical angle is suggested to limit before over of $60^{\circ}$ for safe navigation for boat in wind. Natural results are found that stronger heel moment is observed when sail is used than no sail, and higher angle of attack is induced stronger heel moment.