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펠트 소재의 압축량이 유동저항과 음향특성에 미치는 영향
양윤상(Yoon-sang Yang),이승(Seung Lee) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6
자동차의 실내소음 저감을 위해 사용되는 흡음재는 펠트(Felt)와 같은 섬유형 흡음재와 폴리우레탄 폼과 같은 발포형 흡음재로 크게 구분되는데, 펠트류 흡음재는 두께에 비해 비교적 가볍고 재활용이 가능한 친환경 소재라는 장점 때문에 내연기관차 뿐만 아니라 최근 전기차에서도 널리 사용되고 있다. 펠트류 소재의 자동차 부품은 그 부품과 맞닿는 판넬이나 상관 부품들의 형상에 잘 매칭되도록 성형 금형으로 프레스해 제작되는 경우가 많은데, 이 때 압착된 원소재는 부품 위치와는 상관없이 동일한 면밀도(g/m<sup>2</sup>)를 가지는 반면에 다양한 두께분포를 가지게 되면서 강성이나 유동저항이 달라지게 되고, 결국 흡차음 부품의 음향특성에 영향을 주게 된다. 본 연구에서는 펠트류 흡음재의 압축 정도에 따른 유동저항 값과 음향특성을 확인하였다. 펠트의 압축량이 증가할수록 유동저항도 함께 증가하며, 이로 인해 음향특성 임피던스와 흡음률, 음향투과손실에 미치는 영향을 관찰하였다.
양기근 ( Yang¸ Gi-geun ),홍영근 ( Hong¸ Young-geun ),윤상기 ( Yoon¸ Sang-ki ) 한국융합과학회 2023 한국융합과학회지 Vol.12 No.6
연구목적 본 연구는 소방공무원의 국가직 전환에 따른 소방사무의 국가 책임성 강화 및 지휘체계의 일원화, 소방재정의 안정화, 소방조직법 제정 등 소방사무의 합리화 방안 제시에 목적을 두고 있다. 연구방법 소방 환경의 변화와 소방 활동의 확대 경향에 따른 소방사무 비중의 변화를 소방청 소관법령상의 소방사무 변천 내용을 중심으로 분석하여 연구결과를 도출하였다. 결과 소방사무의 업무비중 변화는 1991년 국가사무 15.4%, 공동사무 21.1%, 자치사무 63.5%이었으나, 2022년 6월 30일 기준 소방사무의 비중은 국가사무 51.5%, 공동사무 19.7%, 자치사무는 28.8%로 변화되어 점차 국가사무의 비중은 증대되고 자치사무의 비중은 감소하는 추세를 보였다. 결론 최근 재난에 대한 사전예방 및 사후 처리 업무의 활동 범위가 확대되면서 국가적 차원의 소방사무가 늘어나고 있다. 이러한 소방 환경의 변화에 따른 소방사무의 국가책임성 강화 및 합리적 재배분을 위해서는 소방조직 구조와 지휘체계의 일원화, 소방재정의 안정화, 소방조직법 제정 및 관련 법령의 정리가 필요한 것으로 나타났다. Purpose The purpose of this study is to present a rationalization plan for fire services such as strengthening national responsibility for fire services and unifying the command system, stabilizing firefighting finance, and enacting the Firefighting Organization Act according to the conversion of firefighters to national public servants. Methods The results of the study were derived by analyzing the changes in the proportion of fire services according to the change in the fire environment and the expansion of firefighting activities, focusing on the changes in the fire services according to the relevant laws of the National Fire Agency. Result In 1991, the change in the proportion of fire services was 15.4% for national affairs, 21.1% for joint(national + local) affairs, and 63.5% for autonomous affairs. However, as of June 30, 2022, the proportion of fire services has changed to 51.5% for national affairs, 19.7% for joint affairs, and 28.8% for autonomous affairs. This shows that the proportion of state affairs is gradually increasing, while the proportion of autonomous affairs is decreasing. Conclusion Recently, as the scope of activities for disaster preparedness and post-disaster handling has expanded, the number of national fire services has increased. In order to strengthen the national responsibility and rational redistribution of fire services in accordance with these changes in the fire environment, it was found that it was necessary to unify the fire organization structure and command system, stabilize fire finance, enact the Fire Organization Act, and organize related laws.
양윤상(Yoon-Sang Yang),백두산(Du-San Beak),이동훈(Dong-Hoon Lee),박춘근(Choon-keun Park),김재철(Jea-Chul Kim) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10
전동차의 지하 터널구간 운행시 승객은 터널 내부의 강한 반사음장의 야기로 인하여 개활지 운행시 보다 열악한 소음환경에 노출된다. 터널내부에 흡음재를 설치하여 반사음장의 강도를 감소시켜 전동차 객실로 전파되는 소음을 저감하기 위한 다양한 연구가 시도되고 있다. 한편 전동차가 터널 내부 운행시 발생되는 고속의 유동이 흡음재의 흡음성능에 어떠한 영향을 미치는지 연구된 바 없다. 따라서 본 연구에서는 유동이 흡음판의 흡음성능에 어떠한 영향을 미치는지를 음향전달함수법을 이용하여 실험을 통하여 확인하고 토의하였다. Passengers in subway train are exposed to a worse noise environment when they are in the tunnel than in the open field. There are many ways to noise reduction techniques in the tunnel, but as an alternative it has been reported to attach sound absorption material on tunnel wall. For this reason sound absorption material for application of tunnel has been studied. But sound absorbing material has not been reported that the sound absorption performance are influenced by high speed flow occurred at subway train in the tunnel. In this study, the effect of the flow on absorption performance of the sound absorption panel is experimentally investigated and discussed.
양윤상(Yang, Yoon-Sang),이동훈(Lee, Dong-Hoon),서은성(Seo, Eun-Sung) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.4
The purpose of this study is to develop a sound absorbing material for indoor which manufactured by a clay and binding material. The seven kind of sound absorbing specimens which sintered through a mold process at high temperature were manufactured for the purpose of testing sound absorption performance. The random and normal sound absorption coefficients were measured for the sintered clay sound absorbing specimens with different particle size, density and mixture ratio. From the experimental results, it was found that its particle size was closely related to the sound absorption performance. It was shown that the sintered clay sound absorbing specimen had the sound absorption properties of a fiber-type or a resonance-type sound absorbing material depending on the particle size.
만성 신부전에서 캄슘 장 흡수율에 미치는 1a Hydroxycholecalciferol 의 효과
성기양(Ki Yang Sung),윤상임(Sang Im Yoon),이강욱(Gang Wook Lee),신영태(Young Tai Shin),노흥규(Heung Kyu Ro) 대한내과학회 1992 대한내과학회지 Vol.43 No.5
Background: Renal osteodystrophy is a major problem in patients with CRF, especially in dialyzed patient. Deficiency of Vitamin D has a important role in the mechanism of renal osterodystrophy. Method: To investigate the effects of 1a (OH) K4 on the calcium metabolism in patients with chronic renal failure, the concentration of serum clcium, phosphorus, parathyroid hormone, the amounts of 24 hours urinary calcium, phosphorus and the rates of intestinal calcium absorption using radioactive 45Ca. 45Ca were measured before administration of la (OH) D3, 1 and 2 weeks after the administration of 1a (OH) D3, 1μg/day in 15 patients with chronic renal failure. The same parameters were measured in 13 healthy controls without medication. Results: 1) The intestinal absorption rate of 45Ca reached at the peak level between 60 and 120 minutes after oral intake of 5μCi of the 45Ca in both patients and controls. 2) The basal intestinal 45Ca absorption rate of the patients were lower than that of the controls (p<0.05) and intestinal 45Ca absorption rates were increased gradually with 1a (OH) D3, administration, especially in patients with low basal serum calcium concentration (< 8 mg/dl). 3) Serum calcium concentration were increased significantly in patients after medication (p<0.05), but serum phophorus, urine calcium and urine phosphorus were not changed. 4) Basal iPTH levels of the patients were markedly higher than controls and decreased significantly within 2 weeks in patient with administration of 1a (OH) D3, Conclusion: 1 a (OH) D3 administration in chronic renal failure is effective to maintain serum calcium level and to prevent renal osteodystrophy through increased intestinal calcium absorption and decreased PTH secretion.
양윤상(Yoon-Sang Yang),이동훈(Dong-Hoon Lee),고재필(Jae-Pil Koh) 대한설비공학회 2014 설비공학 논문집 Vol.26 No.2
An acoustical model for detecting the leak location in a buried gas pipeline has been developed. This model is divided into an experimental model for sound diagnosis, and a theoretical model for sound prediction, which is based on the transfer matrix method, representing the sound pressure and the volume velocity as state variables. The power spectrum is measured by attaching only one microphone to the closed end pipe. It has been shown that the response magnitude of acoustic pressure signals calculated by the acoustical model depends upon the thickness and diameter of a pinhole. The validity for the acoustical model has been verified through a comparison between the measured and calculated results.