• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.39-48
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• 2024

A car horn serves a crucial safety role as a means of communication between drivers and a part that alerts pedestrians in advance. While previous studies have utilized finite element method and electric circuit model to simulate and analyze characteristics of the car horns, there remains a lack of research on design methods of a trumpet horn. This paper presents a design approach that predicts the operating frequency based on the acoustic reactance at the throat of the horn, once the vibrating part is determined. We deal with a horn combining both an exponential horn and a waveguide in the acoustic section, and confirm that the acoustic reactance at the horn throat measured by impedance tube experiment agrees well compared with the numerical result obtained using the finite element method. The resonance frequency of the car horn is predicted using the COMSOL Multiphysics finite element numerical analysis model, and the proposed design method is validated by measuring the operating frequency of the designed horn in a sound pressure experiment. As a result, the resonance measured in a semi-anechoic chamber environment by applying a DC voltage of 12 [V] excluding the holder occurs accurately within a few [Hz] of the design operating frequency. This paper discuss the design method of a trumpet horn from the perspective of the horn's acoustic reactance, and is expected to be useful for designing horn systems.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.57.3-58
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• 2017

We report the detailed design of an unprecedented wideband(band7+8) corrugated feed horn in ASTE focal plane array aiming for future ALMA receiver. We have found that such design constraints as return loss, cross-polarization level, beam width and phase curvature can be controlled by optimizing critical corrugation parameters at the throat and flare region of the horn. The success of optimization manifest itself through simulated aperture effciency over 80 % at the entire frequency range. Physical implications of the resulting corrugation parameters are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.66.2-66.2
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• 2016

KASI and NAOJ are making collaborating efforts to implement faster mapping capability into the new 275-500 GHz Atacama Submillimeter Telescope Experiment focal plane array (FPA). Feed horn antenna is one of critical parts of the FPA. Required fractional bandwidth is almost 60 % while that of traditional conical horn is less than 50 %. Therefore, to achieve this wideband performance, we adopted a horn of which the corrugation depths have a longitudinal profile. A profiled horn has features not only of wide bandwidth but also of shorter length compared to a linear-tapered corrugated horn, and lower cost fabrication with less error can be feasible. In our design process the flare region is represented by a cubic splined curve with several parameters. Parameters of the flare region and each dimension of the throat region are optimized by a differential evolution algorithm to keep >20 dB return loss and >30 dB maximum cross-polarization level over the operation bandwidth. To evaluate RF performance of the horn generated by the optimizer, we used a commercial mode matching software, WASP-NET. Also, Gaussian beam (GB) masks to far fields were applied to give better GB behavior over frequencies. The optimized design shows >23 dB return loss and >33 dB maximum cross-polarization level over the whole band. Gaussicity of the horn is over 96.6 %. The length of the horn is 12.5 mm which is just 57 % of the ALMA band 8 feed horn (21.96 mm).

• Journal of Korean Medicine Rehabilitation
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• v.21 no.2
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• pp.211-226
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• 2011

Objectives : The purpose of this study is to establish literatural evidence about traditional Korean medical physiotherapy through literatural review. Methods : Applicable paragraphs which were related to the traditional Korean medical physiotherapy were phrased from in "Hwang-je-nae-gyung(黃帝內經)", "Yumun-sa-chin(儒門事親)", "Geum-guei-yo-ryack(金匱要略)", "Eui-hack-ip-mun(醫學入門)", "Gyung-ack-jeon-seo(景岳全書)", "Eui-hack-gang-mock(醫學綱目)", "Dong-eui-bo-gam(東醫寶鑑)" where were archiving of Oriental or Korean medicine literatures. Searched paragraphs were analysed for establishing historical and theoretical bases of Korean medical physiotherapy. Results : 1. Theromtherapy is originated from yu(熨), hot hand, warm, water bath, warm earth, fumigation, lamp, torchlight and brazier. Matching indications are various musculoskeletal pain and diseases, skin diseases such as chronic inflammation, frostbite, gynecological and urogenital diseases such as uterine myoma, lower abdominal pain, metrorrhagia, breast diseases, digestive tract diseases such as vomiting, diarrhea, stomachache and also it treats cardiovascular disease. Other matching indications are sunstroke, rhinorrhea, psycosis and anal pain. And it used helping acupuncture therapy. 2. Cryotherapy is originated from lengfu(冷敷), lengtie(冷貼), cold stone and cold water. Matching indications are various fever disease, skin diseases such as acute inflammation, wound, fever skin disease, otorhinolaryngological diseases such as acute sore throat, otitis, stomatitis, nasal bleeding and contusions, abrasions, burn and dysuria. In addition, it treats extremity coldness, chillness, stomachache caused to accumulate fever. 3. Physiotherapy by circulating meridian system is originated from manipulation such as pushing, massage and beating to therapy point. Matching indications are musculoskeletal diseases such as various muscular pain, heavy sensation, convulsion, urogenital diseases such as dysuria, lower abdomen pain, digestive tract diseases such as stomachache, and paralysis due to blocked meridian system. And other matching indications are psycosis, leprosy, hypoesthesia, acute stroke. In addition it helps other therapy methods. In addition, the power of manipulation classify to strengthen and reduce. 4. Physiotherapy by balancing meridian system is originated from sunshine, magnet, horn, bamboo and tube. Sunshine helps improving self's care and cure inflammatory skin disease. Magnet's matching indications are paralysis, various injuries, abscess, fever and eye disease. Cupping therapy treats to skin diseases and internal diseases such as tuberculosis. Conclusions : Traditional Korean medical physiotherapy was widely used in traditional Korean medicine since ancient time based on the traditional Korean medical principle and anatomical knowledge. With modern physiotherapy and traditional Korean medicine together, effects of treatment are enhanced. And traditional Korean medical physiotherapy is appropriated to world physiotherapy's expectation.