• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.1-8
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• 2005

For study on the unsteady wall interference effect, flows around a circular cylinder in closed test-section wind tunnels have been numerically investigated by solving compressible Navier-Stokes equations. The numerical scheme is based on a node-based finite-volume method with the Roe's flux-difference splitting and an implicit time-integration method coupled with dual time-step sub-iteration. The computed results showed that the unsteady pressure gradient over the cylinder is enhanced by the wall interference, and as a result the fluctuations of lift and drag are augmented. The drag is further increased because of the lower base pressure. The vortex shedding frequency is also increased by the wall interference. The pressure on the test section wall shows the harmonics having the shedding frequency contained in the wall effect.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.395-404
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• 2012

This paper presents computations of the dynamic derivatives of three dimensional flight vehicle configurations using CFD. The pitch dynamic derivatives are computed from the pitch sinusoidal motion, while the roll damping is computed based on steady state calculation using a non-inertial frame method. The Basic Finner and the SDM(Standard Dynamic Model) are chosen for the benchmark tests against other numerical and experimental results. For the flow calculations, a 3-D Euler solver that can be run both on the non-inertial frame and on the inertial frame is developed. A dual-time stepping method is applied for the unsteady time accurate simulations. A good agreement of pitch-roll dynamic derivatives with previously published numerical results and the experimental results is observed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.3
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• pp.225-231
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• 2011

The satellite clock anomalies, one of the abnormal signal factors of the GPS satellites, can have a significant impact on the GPS measurements. However, it can be difficult to detect the anomalies of the satellites clock before the range of the satellites clock error becomes bigger than the range of the other factors, due to the measurement including error of the orbit, ionosphere delay, troposphere delay, multipath and receiver clock. In order to perform quick and accurate detection by minimization of critical range in anomalies of the satellites clock, this paper suggested a solution to detect precise anomalies of the satellites clock after application of carrier smoothing filter from measurement by dual-frequency and adjustment of errors which can be occurred by other factor and the receiver clock errors. The performance of the proposed method was confirmed by comparing to the satellite clock biases which are provided by IGS.

• Journal of the Korean Home Economics Association
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• v.24 no.4
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• pp.147-162
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• 1986

This research has dual purposes. First, it was designed to determine the level of children's spatial environment in the residences, thereby, to make a vision for children's furniture as an industrial design product. Second, it was intened to find out the children's perceptual pattern toward the furniture, thereby to give some implications for future design development. For the second purpose, descriptors were screened with construct validity and their factor structure was identified. The subjects were 1,197 children from 1st grade of elemantary school through 3rd grade of middle school, and their 1,197 parents for the first purpose, and 560 children from 6th grades of elemantary school and 3rd grade of middle school for the second purpose. The first parts of findings were 1) present interests of parents of household above middle income level in Seoul in making their children's spatial environment desirable is quite high. 2) Space segregation stage in terms of physical and conceptual aspects showed very fast development, that is, there will have been very good changes for children's room to be a very well furnished and independent space for them. 3) Children's opinions were quite well reflected when purchasing the present furniture, and this tendency seemed to be more likely happend in future. These findings mentioned above gave and confirmed the visions for future children's furnished environment. The second parts of findings were such that the perceptual pattern for furniture by children showed aesthetic design appearance, functionality and durability, and the characteristic of line. This result impliated especially that designers should be every careful to manipulate or use the line of the furniture products. The 22 representative descriptors selected can be used as an evaluation instrument for furniture products.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.1
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• pp.1-12
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• 2001

The biotope network of Susung gu is characterized as dense residence zones forming its core that enable partial biotope in and around the residential zones. First, in district I, it is possible to make these zones connected to the third district. In district II, which is abundant in biotope, it is very important not to continue destoyi9ng the existing biotopes. In the case of district III, old residence zones have fill the severe gap between forests and the Sinchun river, through redevelopment, which covers more than 30% of the biotope area with large scaled linear residence areas. In the case of district IV, limited destruction of biotope and the improvement of nature areas were suggested as the alternative for preservation of biotopes. Consequently, in the construction of the biotope network in Su-sung gu, the maintenance of existing biotopes is required. Int he old residence zones, as redevelopment occurs, by maintaining biotope area of more than 30% and making the scale of residential complexes more than 1ha, it is possible for old residence zones to accomplish the role of providing important green spaces. In the case of newly developed residential zones, by reducing the rate of pavement of traffic conducts, utilizing small sized parks at the junctions and the plantation of trees along the corridors, the entire residence zones are able to accomplish the role of providing important green space. The problem houses and connecting the inner green space of the private houses with the green spaces of the streets in some areas. Futhermore, green spaces of forests must not be used for urban development. Dual planting on sidewalks, planting plots dispersed among streets and median strips must be established on road, too.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.3
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• pp.25-38
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• 2000

The research follows several steps. First, the chinese 'WangSung' and 'KungSi' System are verified positively. Next, the structure of palace in Choson Dynasty is deduced based on those chinese systems. Finally, the common system that is also applied in other government-operated spaces is found. The result can be summarized as follows. It is clarified from reviewing the chinese 'WangSung' and 'KungSil' Systems that the 'OyoiCho' is located in 'WhangSung(the imperial city) but out of' KungSung(the palace). Therefore, the research points out that all sort of theories explaining the 'OyoiCho' of Choson Dynasty is a space of 'in-place' are false. The palace system of Choson dynasty seeks the substantiality grounded on the substantial function of 'SamCho(three spaces)' rather than its strict principle dividing main spaces by several doors-'KungMoon' Moreover, it is also certified that the 'ChonChoHooChim' system, literally the political court is located at the front and the private section is at the other(back) side, is directly applied on the palace of Choson Dynasty. This idea has been developed into 'inner and outer' concept and repressed in palace as the 'OyoiChon(outer palace) and NaeChon(inner palace)' concept. conclusion, the research suggests that the dual concept in space such as 'ChonHoo(front and back) and 'NaeOyoi(inner and outer)' basically comes from 'Eum Yang' theory and influences in building other government-operated spaces: for example 'ChongMyo(the royal ancestors shrine)', 'SoWon(a private school of Choson dynasty), 'HyangKyo(a local school annexed to the Confucian shrine)' and 'KwanAh(a governmet agency)'

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.2
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• pp.69-78
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• 2006

This paper is concerned with analyzing the images of Korean automobiles using, so called, sensory engineering, which adapts the sensory and subjective assessment of human beings in evaluating the quality of product. The methodology of analysis is suggested in this paper according to the following steps. First, 14 pairs of adjectives, which describe the image of object cars in view of the semantic differential method, are derived from consulting with several expert panels. Nextly, factor analysis is performed in order to obtain the axises, by which the images space of the object automobiles are specified, and then the images of the object automobiles are measured by the coordinate of all the object automobiles in the image space. In this paper, a sensory estimation experiment is performed to a panel consisting with In undergraduate students residing in the region of Daegu. From the result of analysis of this paper, target images, which the automobile manufacturers are intended, are achieved by and large except one company.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.11
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• pp.909-917
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• 2021

In this work, a one-dimensional combustor solver was constructed for the scramjet control m odel. The governing equations for fluid flow, Arrhenius based combustion kinetics, and the inje ction model were implemented into the solver. In order to validate the solver, the zero-dimensi onal ignition delay problem and one-dimensional scramjet combustion problem were considered and showed that the solver successfully reproduced the results from the literature. Subsequentl y, a ramjet analysis algorithm under subsonic speed conditions was constructed, and a study o n the inlet Mach number of the combustor was carried out through the thermal choking locatio ns at ram conditions. In such conditions, a model for precombustion shock train analysis was i mplemented, and the algorithm for transition section analysis was introduced. In addition, in or der to determine the appropriateness of the ram mode analysis in the code, the occurrence of a n unstart was studied through the length of the pseudo-shock in the isolator. A performance a nalysis study was carried out according to the geometry of the combustor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.921-933
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• 2018

There is a method to enhance the pure navigation performance of INS(Inertial Navigation System) through the rotation of inertial measurement unit to compensate error sources of inertial sensors each other and that INS using this principle of operation is called rotational INS. In this paper, the exact error analysis of rotational INS based on ring laser gyro considering the coupling effect with gravity and earth rate is performed to evaluate the navigation performance by inertial sensor error sources. And error analysis and performance evaluation result confirmed by modelling and simulation is also proposed in this paper.

• Journal of Yeungnam Medical Science
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• v.39 no.4
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• pp.285-293
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• 2022

Background: This study was conducted to analyze the effects of low skeletal muscle mass index (SMI) and obesity on aging-related osteoarthritis (OA) in the Korean population. Methods: A total of 16,601 participants who underwent a dual-energy X-ray absorptiometry and 3,976 subjects with knee X-rays according to the modified Kellgren-Lawrence (KL) system were enrolled. Knees of ≥KL grade 2 were classified as radiologic OA. The severity of joint space narrowing (JSN) was classified by X-rays as normal, mild-to-moderate, and severe JSN in radiologic OA. The subjects were grouped as normal SMI (SMI of ≥-1 standard deviation [SD] of the mean), low SMI class I (SMI of ≥-2 SDs and <-1 SD), and low SMI class II (SMI of <-2 SDs). Obesity was defined as a body mass index (BMI) of ≥27.5 kg/m². Results: The modified KL grade and JSN severity were negatively correlated with the SMI and positively correlated with BMI and age. The SMI was negatively correlated with age. JSN severity was significantly associated with a low SMI class compared to a normal SMI, which was more prominent in low SMI class II than class I. Obesity was significantly associated with more severe JSN, only for obesity with a low SMI class. Furthermore, patients with a low SMI class, regardless of obesity, were prone to having more severe JSN. Conclusion: This study suggested that a low SMI class was associated with aging and that an age-related low SMI was more critically related to the severity of JSN in OA.