• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.71-79
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• 2006

Swirl injector with multi-stage tangential entry was analyzed to suppress high-frequency combustion instability in Liquid Rocket Engines. In order to analyze the effect of swirl injector as an acoustic absorber, swirl injector was regarded as a quarter-wave resonator and it's damping capacity is verified in atmospheric temperature. It has a finite mode of vibration and natural frequencies which can be tuned to the natural frequencies of a model combustion chamber. The interior air core shape of injector is more stable in the case of using the swirl injector with multi-stage entry than with single-stage entry. Also, when the swirl injector with multi-stage entry is used, tuned-injector length for unstable mode is well agreed with the calculated length. From the experimental data, it is proved that if the interior air core shape of swirl injector is stable, the fine tuned swirl injector can decrease the unstable mode of model chamber effectively and increase the damping rate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.51-60
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• 2002

The Monte-Carlo simulation of statistical analysis is used to investigate the final conditions of states as well as the footprint boundaries resulting from the atmospheric re-entry dispersions. The re-entry dispersions in this paper are specified by a $7\times7$ covariance matrix of latitude, longitude, altitude, bank angle, flight path angle, heading error, and range at entry velocity. The error sources that affect these at re-entry for a deboost are the uncertainties associated with atmospheric density and temperature, initial errors, wind, and estimation error of aerodynamic coefficients. Using $3{\sigma}_n$ deviations of these errors and a nominal flight trajectory, the covariance matrix of state variables can be determined by performing a trajectory error analysis. Major considerations in the application of the Monte-Carlo method are the simulation of perturbed trajectories, bank reversal, and determination of the impact points for each of these trajectories. This paper analyzes the results of uncertainties from the viewpoint of aero-coefficients and bank reversal.

• Journal of the Korean Institute of Rural Architecture
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• v.15 no.1
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• pp.39-46
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• 2013

There have been numerous researches on Nak-An village in Jeollanamdo, one of the most representative traditional castle village in Korea. Most of them have dealt with general and physical architectural scale and features separately. Therefore this study aims to understand the compositional characteristics of building layout and exterior space and the relations between street system and dwelling unit of folk houses in Nak-An village. The study examined houses of ordinary people in Nak-An village constructed before the village was not affected by foreign influences. 36 folk houses in Nak-An built from nineteenth century to early twentieth century and believed to have few physical changes from the original floor plans and architectural forms were the subjects to be analyzed. The most popular types in building layout are "Open L"and "Open U". The most typical orientation of main building is Southwest. The favorable entry into the dwelling lot is from the side. The street system in the village consists of main streets of South-North, resulting in dwelling lots with North-South axis most general. This site condition forces the entry into the lot from North main street and the side access to the main building. From these findings, the building layout and the entry into the dwelling lot of folk houses in Nak-An are strongly related with street system and conditions of dwelling lot.

• The Korean Journal of Pain
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• v.23 no.1
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• pp.11-17
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• 2010

Background: The target of lumbar sympathetic ganglion block is the anterolateral surface of the L2, 3 and 4 vertebral bodies, where the lumbar sympathetic ganglion usually lies. In most cases, a block-needle is inserted approximately 5-8 cm lateral to spinous process on the skin and directed to the anterolateral surface of vertebral body obliquely. The purpose of this study is to determine the safe entry angle and entry point in Korean by using the abdominal CT scan images. Methods: The abdominal CT images of eighty five patients were recruited to this study. The minimal angle aimed at the lumbar sympathetic ganglion that can pass through the lateral aspect of body and maximal angle that avoids puncturing the kidney, ureter or retroperitoneal space were measured. The distance from midline to skin entry point was also measured. Results: There was no significant difference in entry angle among L2, 3, and 4 level. The entry angle was similar in the right and left side, and in males and females. The entry angle of old age group was significantly smaller than that of young age group. The calculated safe entry angle was $30.5{\pm}0.4^{\circ}$ and entry point was $7.7{\pm}0.2\;cm$ and $6.7{\pm}0.1\;cm$ lateral from midline in males and females respectively. Conclusions: These measurements can be used as a reference for lumbar sympathetic ganglion block and radiofrequency lesioning. Prior to performing the lumbar sympathetic ganglion block for cancer patients, the abdominal CT scan should be reviewed to prevent complications.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.78.2-78.2
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• 2008

• Journal of Korean Society of Rural Planning
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• v.22 no.3
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• pp.49-61
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• 2016

This study examined the effectiveness of and satisfaction of visitors with the Environmental Improvement Project on national parks' trail entry areas. A survey was conducted to improve the proposal framework based on the data. Data for the study were obtained from 6400 respondents who used 28 national park offices at 32 national park trail entry areas. The field research was collected in 3200 surveys, divided between pre- and post-implementation of the Environmental Improvement Project. The study variables consisted of socio-demographics, visitors' perceptions on the environmental improvement of trail entries, effects of the environmental improvement, and visitor satisfaction. Several important results were found. First, the environment of trail entries has a significant impact on the formation of images and user satisfaction of national parks. Second, the influence of the trail entry improvement showed that 71.8% of visitors rated the trail entry as environmentally friendly after the Environmental Improvement Project, compared to 48.5% of visitors rated the trail entry as environmentally friendly before the Environmental Improvement Project. The findings indicated that a top priority of environmental improvement of the trail entries needs to be the installation of convenience facilities such as rest areas, restrooms, and direction boards (pre: 34.5%, post: 32.6%). Third, functionality and the other nine variables were shown to enhance the effect of the environmental improvement of the trail entries at the 1% statistical significance level. Finally, results indicated that the overall satisfaction of the visitors with the park was significantly higher after the environmental improvement (t-value=25.741, p=.000), showing the satisfaction score was higher after the environmental improvement (pre: 3.51, post: 4.12), with a statistically significant difference at the 1 % level. This study helps to understand trail entries, which have influenced the image of the national park and satisfaction. These findings can be utilized to manage and design a national park as a public space.

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.80-89
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• 2013

The amount of object which reenter the Earth's atmosphere has been increasing after the Sputnik I launch in October 1957. Most of reentry objects were incinerated by aerodynamic heating so they hardly survive. But they may incur casualties and widespread property damages if they survive and fall to surface. The amount of reentry objects, such as Satellite, Rocket Booster, Pressure Tank, ISS shows continued growth as byproduct of space activities. Most of the re-entry objects are incinerated at between altitude of 50km~80km and 10%~40% of the objects are surviving and falling to the ground. Therefore, this paper try to piece together the reentry event and analysis the survival characteristics of re-entry object.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.75-81
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• 2002

In the re-entry comtrol system, errors apt to induce because the time deriviative of drag acceleration is analytically estimated. Still more, the difficulty of estimation of th exact drag coefficient in hypersonic velocity and the non-reality of the scale height cause a steady-state drag errer. In the Space-Shuttle, a steady-state drag error is reduced by the addition of the integral term of drag acceleation error into the control system. This method, however, induces a difficulties in respect to the modern controller composition due to the multi-poles in a closed-loop system. Thus, this paper proposes the additional method of the disturbance observer. This reduces the steady-state drag error according to the following by the analytic calculation, and then creates the new drag acceleration time derivative using the estimated error. The performance of the re-entry control system is verified about 32 refernce trajectories.

• Journal of architectural history
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• v.9 no.2 s.23
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• pp.33-48
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• 2000

This study aims to analyze the construction of Kyungsang KAMYOUNG in the late Chosun dynasty by restoring its constructive system and relating it with the office organization. followings are the summary of this study. 1. Government office of Daegu consists of inn(KAEGSA), Kyungsang KAMYOUNG, and Daegu city hall(BUA), and JINYOUNG. 2. The layout of virtual placement is shown in the in the text. Even though it had been newly constructed due to three times of fire, the fundamental scheme of space is found out not to have been changed since mid-eighteen century at the latest. 3. Followings are the result of analyzing the space of KAMYOUNG, after dividing its space into entry area, main business area and police military business area in the aspect of business. First, entry area consists of 2 door system with external door(UOISAMMUN) and internal door(NAESAMMUN). Second, main business area consists of facilities for inspector, public officials, and low grade employee respectively This space is divided into SUNHWADANG area and JINGCHONGKAK area, and the former consists of active business facilities, and the latter consists of passive business facilities focusing on the rest facilities. Third, business support area consists of facilities for low grade employee and minor assistant respectively, which are placed to the left and right of POJONGMUN and KWANPUNGRU. Fourth, police military business space is in middle(JUNGYOUNG) and forms separate areas to the east of SUNHWADANG. Accordingly, It is certain that the space of Kyungsang KAMYOUNG had been placed in accordance with the nature of business per position.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1388-1395
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• 2009

In March 2007, Korea's Ministry of Construction & Transportation (MOCT) established "Guidelines on the Computerization and Use of Geotechnical Investigation Results," which took effect as official instructions. The 2007 Geotechnical Information DB Construction Project is underway as a model project for a stable geotechnical information distribution system based on the MOCT guidelines, accompanied by user education on the geotechnical data distribution system. This study introduces a geotechnical data entry system characterized by the standardization of the geotechnical investigation form, the standardization of metadata for creating the geotechnical data to be distributed, and the creation of borehole space data based on the world geodetic system according to the changes in the national coordinate system, to define a unified DB structure and the items for the geotechnical data entry system and to computerize the field geotechnical investigation results using the MOCT guidelines. In addition, the present operating status of the geotechnical data entry system and entry data processing statistics are introduced through an analysis of the model project, and the problems of the project are analyzed to suggest improvements. Education on, and the implementation of, the model project for the geotechnical data entry system, which was developed via the standardization of the geotechnical investigation results form and the metadata for institutions showed that most users can use the system easily. There were problems, however, including those related to the complexity of metadata creation, partial errors in moving to the borehole data window, partial recognition errors in the installation program for different computer operating systems, etc. Especially, the individual standard form usage and the specificity of the person who enters the geotechnical information for the Korea National Housing Corporation, among the institutions under MOCT, required partial improvement of the geotechnical data entry system. The problems surfaced from this study will be promptly addressed in the operation and management of the geotechnical data DB center in 2008.