• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.12
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• pp.553-558
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• 2002

In this paper, an integrated balun using bondwire transformer is fabricated and measured. The bondwire transformer has 1ow conductor and substrate loss and kas high resonance frequency. So it is available to implement low loss broadband balun. From the measured results, 0.7 dB amplitude imbalance and about 2.5 $^{\circ}$ phase imbalance was achieved from 8.15 to 16.18 GHz. It is expected that the proposed balun can improve the performance of mixers, amplifiers and matching networks of antennas. It can also be integrated with other components due to its easier fabrication and smaller size than spiral transformer balun.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.45.1-45.1
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• 2015

Hayabusa is the JAXA's space mission that succeeded in sample-return from S-type asteroid (25143) Itokawa. During the rendezvous phase, more than a thousand of images were taken with the Asteroid Multi-band Imaging Camera (AMICA). It is valuable to study the regional variation of the optical properties on the asteroid using these images to know the generality and uniqueness of the returned samples. In addition, AMICA images are important in that they provide unique data set at low phase angle (i.e Sun-Itokawa-AMICA's angle) that have not been explored in the previous asteroidal missions. At the previous conference (2015 KAS spring meeting), we introduced our preliminary data analysis of AMICA data without considering the shape model of Itokawa and mentioned. In this study, we present a new result obtained through further analysis, taking account of the shape model of the asteroid. We thus utilized "plate_renderer" tool to derive Hapke model parameters at different terrains. It is found that the opposition amplitude (parameter B0) is consistent with those of the other S-type asteroids while the opposition width (parameter h) is significantly narrower than those of the other S-type asteroids. At this conference, we plan to describe the regional variation of photometric properties on Itokawa.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.435-445
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• 2012

In this paper, a design process is established by integrating aviation safety requirements for the development of general aviation aircraft. An Airworthiness-Design Integration System, which integrates certification requirements with the entire design/analysis process, is developed and presented. For the proposed system, KAS 23/FAR 23/AC 23/CS 23 certification regulations are analyzed to determine design constraints and system compliance checks and to construct an ER&G (Engineering Requirement and Guide) and a Design-Certification Related Table (DCRT). Furthermore, through building a DB (Data Base), the management of design and certification related resources for developing a FAR 23 class aircraft are made. Certification tools and resources are also efficiently managed by the DB. The connection between the certification requirements and the detailed design process is proposed in this system. Tracking of this proposed method is validated by configuring a USE CASE and a system. The Airworthiness-Design Integration system will be constructed based on the system's design plan, certification system, and usage scenarios.

• Journal of Korean Society of Transportation
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• v.24 no.3 s.89
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• pp.29-37
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• 2006

As a recurrent congestion of urban freeway occurs in almost same time and section, it is possible to manage the congestion effectively by the expectation and advance correspondence. In the existing traffic management system. we have used pattern data to manage a recurrent congestion. But it is not applicable to an urban freeway which kas various traffic circumstance. In this study, the probability by travel speed using a statistical distribution method will be used to predict the probability of recurrent congestion. It is expected that we can get the point of time and the duration of recurrent congestion, and we can devise an effective advance correspondence and a transportation operation.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.1-7
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• 2016

Since 2014, MOLIT (Ministry of Land, Infrastructure, and Transport) is carrying out a KASS project to develop and construct Korean SBAS. KASS can cause damage of human & properties if it has some problem during operation. Therefore, system safety assessment for KASS development is very important. Principal point of system safety assessment is the allocation of DAL(design assurance level) based on the hazard identification and classification. In this parer, the author conducts the allocation of DAL for KASS & its sub-systems based on the international standard(SAE ARP4761), which suggests a best practice of aviation system safety assessment. The result of this paper are the first step of system safety assessment, and can be used for further system safety assessment of KASS project.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.1007-1013
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• 2003

As environmental restriction kas continuously become more strict, machining technology has emphasized on development of environment-friendly technology. In cutting technology, it has been well recognized that cutting fluids might have undesirable effects on workers health and working environment. In this study, compressed cold air was used as a replacement for conventional cutting fluids. The cooling effect on cutting tool was analyzed using the finite element method and the computational fluid dynamics. This study focused on the temperature simulation of cutting tool by real flow analysis of cold air. The maximum flow rate and the minimum temperature of compressed cold air are 300ι/min and -30$^{\circ}C$ respectively. To compare the simulation and experimental results, inner temperature of the cutting tool was measured with the thermocouple embedded in the insert. The results show that the analysis of cutting temperature using FEM and CFD is resonable, and the replacement of cutting fluid with cold air is available.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.75.1-75.1
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• 2010

The nature and origin of the intergalactic magnetic field (IGMF) are an outstanding problem of cosmology, yet they are not well understood. Measuring Faraday rotation (RM) is one of a few promising methods to explore the IGMF. We have theoretically investigated RM using a model of the IGMF based on a MHD turbulence dynamo (Ryu et al. 2008; Cho et al. 2009). In the previous KAS meeting, we reported the results for the present-day local universe; for instance, the probability distribution function (PDF) of ${\mid}RM{\mid}$ follows the lognormal distribution, the root mean square (rms) value for filaments is ~1 rad m^{-2}, and the power spectrum peaks at ~1 h^{-1} Mpc scale. In this talk, we extend our study of RM; by stacking simulation data up to redshift z=5 and taking account of the redshift distribution of radio sources, we have reproduced an observable view of RM through filaments against background radio sources. Our findings are as follows. The inducement of RM is a random walk process, so that the rms of RM increases with increasing path length. The rms value of RM for filaments reaches several rad m^{-2}. The PDF still follows the lognormal distribution, and the power spectrum of RM peaks at less than degree scale. Our predictions of RM could be tested, for instance, with LOFAR, ASKAP, MEERKAT, and SKA.

• Journal of Korean Medical classics
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• v.33 no.3
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• pp.63-89
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• 2020

Objectives : To suggest conditions that will allow for change in Traditional Korean Medicine (TKM) curricula through analysis of the failure of widespread acceptance of the integrated curriculum into all Traditional Medicine Colleges. Methods : First, the process of change between TKM education and medical education was compared. Next, the conditions that would stimulate change in TKM curricula were analyzed in three levels: structure, policy, and actor. Results : TKM colleges have not experienced a structural change from the six-year to four-year structure. The accreditation standards of TKM education (KAS2021) should be more supportive instead of forcing change, and the goals should be reset to education improvement instead of meeting the standards of WFME. The deans' leadership and professors' ownership over their subjects need to be modified. A group of professionals that could lead change is required, while other factors such as full-time professorships, clinical practice hours, obligatory teaching hours and overall teaching environment need to be improved. Conclusions : It would be ideal if individual TKM colleges created success models of curricula change-despite the time and effort that is required-that could spread to other colleges. After the new curriculum has been accepted in more that half of the total eleven TKM colleges, an institutional isomorphism can be demanded.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.3
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• pp.1-9
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• 2011

In this paper, a conceptual design process for Very Light Jet aircraft has been proposed incorporating aircraft safety certification. During the proposed design process, satisfaction of the airworthiness certification for an intermediate resulting aircraft configuration is evaluated and then redesigns are carried out if necessary and until the designed aircraft configuration satisfies the airworthiness requirements. Certification database has been developed using FAR 23, AC 23, KAS 23, and CS 23 as the airworthiness certification. Based on the developed certification database Design Certifcation Related Table has been produced to use the airworthiness requirements as design constraints in the propsed design process. Using Quality Function Deployment the design variables for a redesign are carefully selected and a design optimization is performed. To demonstrate the feasibility and effectiveness of rapid aircraft conceptual design using the proposed approach, a Very Light Jet design optimization including a redesign of wing flap has been performed and the design results have been presented.

• Journal of Aerospace System Engineering
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• v.7 no.2
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• pp.23-28
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• 2013

This is a research on the method of how to improve lateral stability for the small general aviation airplane to meet the FAR part 23 requirements. This research is based on the experience of certification flight tests of KC-100 airplane for Korea first type certification. KAS/FAR Part 23.177 is the static lateral and directional stability requirement. And, 23.177(b) requires to show the tendency to raise the low wing in steady heading side slip maneuver. However, it is very difficult for the low wing to be raised at the low speed during the steady heading side slip maneuver. So, the requirement allows not be negative at the $1.2V_{S1}$ speed and takeoff configuration. (static stability requirement requires low wing picked up at any speed except $1.2V_{S1}$ speed and takeoff configuration) In this paper, the static lateral stability requirements and the lessons & learned of KC-100 airplane certification flight test results are shown.