유니텍스 구조의 차음성능 향상기술 개발

변준호,이중혁,김석현,이재준,기호철,Byeon, Jun-Ho,Lee, Joong-Hyeok,Kim, Seockhyun,Lee, Jae-Joon,Ki, Ho-Cheol 대한기계학회 2016 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.4 No.2

유니텍스는 높은 강도과 우수한 단열성, 긴 수명 및 간편한 시공에 따른 저렴한 제작비 때문에 대부분의 도시철도 차량의 바닥 구조로 널리 사용되고 있다. 그러나 여러 가지 우수성에도 불구하고, 이 구조는 차량 적층재에서 중요한 차음성능 측면에서는 여전히 문제점을 갖고 있다. 기존 제품은 중량대비 차음성능의 척도인 질량법칙 투과손실치에 비해 현저히 낮은 투과손실을 보인다. 최근 차량 제작사와 시공사는 차음성능을 높이기 위하여 많은 노력을 시도하여왔으나 큰 효과가 없었다. 이에 본 산학협동 연구에서는 기존 제품 대비 5dB 이상 차음성능을 향상시키는 것을 목표로, 적층재의 구조개선 방안을 도출하고 개선효과를 실험적으로 검증한다. Unitex is widely used for the floor structure of urban railway vehicles because it shows good structural safety and heat insulation, has long life, and lowers the cost owing to easy installation. However, in spite of these merits, Unitex has a limit to the sound insulation performance, which is very important in vehicle structure. It shows a sound transmission loss considerably lower than the mass law value, which indicates the sound insulation performance per unit weight. Recently, railway vehicle manufacturers and Unitex supplier have tried to improve the sound insulation performance of Unitex, but meaningful results have not been achieved yet. Through the industry-university collaborative research, we propose structural improvement methods to increase the sound transmission loss by more than 5dB and we then verify the effect by performing experiments.

주름강판의 차음 성능과 모드 밀도

변준호(Jun Ho Byeon),이중혁(Joong Hyeok Lee),김석현(Seockhyun Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

In a railway vehicle, corrugated steel panel is widely used for the floor structure because of the high bending stiffness per weight. However, corrugated steel panel shows lower sound insulation performance than that of the flat plate with the same weight. Especially, in a particular frequency band, the sound transmission loss significantly decreases. Local resonance is known as the main reason of the sharp decline of the sound transmission loss. Above a certain frequency band, modal density rapidly increases as a large number of local resonance modes occur. In this study, we estimate the sound transmission loss of the corrugated steel panel in respect of the modal density. Modal density of the corrugated steel panel is calculated by finite element analysis and the sound transmission loss is measured based on ASTM E2249-02. The result will be applied to improve the sound insulation performance of the corrugated panels.

감쇠비 추출을 위한 포락선 대수감소법의 타당성 분석

변준호(Jun Ho Byeon),김석현(Seockhyun Kim) 한국소음진동공학회 2019 한국소음진동공학회 학술대회논문집 Vol.2019 No.10

균형추를 갖는 공진형 교반기의 진동 해석

변준호(Jun-Ho Byeon),김영선(Yeong-Seon Kim),김석현(Seockhyun Kim) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

The resonance type mixer requires a large vibration in the container for the mixing operation. At the same time, it is necessary to minimize the transmission force to the frame for work stability. For this purpose, a balancing weight is connected to the container. In this study, the equations of motion for a resonance type mixer with a balancing weight were derived and eigenvalue analysis was performed. The existence of a resonance mode suitable for mixing was confirmed through the analysis. There was a natural vibration mode in which the container and the balance oscillate in the opposite direction. By resonating it, it was possible to cancel the transmission force to the body. We also proposed a method to reduce the vibration of the motor part as much as possible by setting the amplitude ratio of the container part and the motor part as a design variable.

알미늄 압출재의 모드밀도와 투과손실

변준호(Jun Ho Byeon),이중혁(Joong Hyeok Lee),이준영(Jun Young Lee),김석현(Seockhyun Kim) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4

Aluminum extruded panel is widely used in a railway vehicle since its core structure dramatically increases the bending stiffness per weight. However, extruded panels show lower sound insulation performance than that of the flat plate having the same weight. Especially, in a particular frequency band, the sound transmission loss significantly decreases. Main reason of the problem is known as the local resonance. A number of local resonance modes occur above a certain frequency band and modal density rapidly increases. In this study, we investigate the relation of the sound transmission loss and the modal density of aluminum extruded panels. Finally, we propose a design methodology to estimate the sound transmission loss of extruded panels.

신라대종의 진동과 음향

김석현,이중혁,변준호,Kim, Seockhyun,Lee, Joong Hyeok,Byeon, Jun Ho 한국음향학회 2017 韓國音響學會誌 Vol.36 No.3

신라대종은 성덕대왕신종을 계승하여 새 천년을 울리기 위해 제작되었다. 본 연구에서는 신라대종이 구조와 음향 측면에서 성덕대왕신종과 어떻게 유사한지를 조사하였다. 먼저 설계 및 제작 과정을 소개하고 두 종의 크기를 비교하여 유사성을 평가하였다. 한국 종소리의 세 가지 주요 특성은 웅장하고 조화로운 타격음, 역동적인 맥놀이와 길게 지속되는 여음이다. 이 세 가지 특성을 물리적 인자를 사용하여 객관적으로 평가한다. 이를 통하여 수려한 외관과 웅장하고 아름다운 소리를 내는 대형 한국 범종의 제작에 유용한 자료를 제공하는 것이 본 연구의 목적이다. Silla Great Bell was manufactured in order to ring for the new millennium in succession to King Seongdeok Divine Bell. This study investigates how Silla Great Bell is similar to King Seongdeok Divine Bell in respect of structure and sound. First, design and manufacturing processes are introduced and dimensions of the two bells are compared and the similarity is estimated. Three main characteristics of the sound of a Korean bell are magnificent and harmonic striking sound, dynamic beat, and long lasting hum tone. These three features are compared and objectively estimated using physical parameters. The purpose of the study is to provide useful information to manufacture Korean bell which has beautiful appearance and excellent sound.

풍력타워용 무지향성 흡진기의 성능 분석

오승준(Seung Jun Oh),변준호(Jun Ho Byeon),김석현(Seockhyun Kim) 한국소음진동공학회 2018 한국소음진동공학회 학술대회논문집 Vol.2018 No.10

2018 평창동계올림픽대종의 맥놀이 조절

이중혁(Joong Hyeok Lee),변준호(Jun Ho Byeon),김석현(Seockhyun Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

Great Bell of Pyeong Chang 2018 Winter Olympic Games (Olympic Games Bell) was made to commemorate the 2018 Winter Olympic Games and pray for successful hosting. The aim of the study is to make a dynamic sound suitable for the Olympic Games. It can be achieved by the strong beat of the sound. Beat is due to the slight asymmetry occurring in the casting process. Beat period of the Olympic Games Bell was too long after casting and the beat had to adjust. In this study, we introduce a beat control method using an equivalent bell. The mode pair arrangement of Olympic Games Bell was identified after casting and the equivalent bell was constructed. The location and size of local grinding to make a proper period of beat were determined through the simulation using the equivalent bell. Finally, the proper beat period was obtained to make a dynamic sound.

2018 평창동계올림픽대종의 맥놀이 조절

이중혁(Joong Hyeok Lee),변준호(Jun Ho Byeon),김석현(Seockhyun Kim) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.5

2018 평창 동계올림픽대종(이하 올림픽대종)은 2018 동계올림픽의 성공적인 개최를 기원하기 위하여 제작되었다. 올림픽대종은 항아리 모양의 전통 범종 구조에 세계 스포츠 축제를 기념하는 역동적인 소리를 내도록 설계되었다. 종소리가 힘차게 들리기 위해서는 맥놀이가 선명하고 주기가 너무 짧거나 길지 않아야 한다. 그러나 맥놀이는 주조과정에서 발생하는 미세한 비대칭성에 기인하므로 설계단계에서는 예측이 불가능하다. 주조 후 올림픽대종의 맥놀이는 거의 들리지 않을 정도로 주기가 지나치게 길었다. 본 연구에서는 등가 종 모델을 이용하여 맥놀이 주기를 조절하였다. 맥놀이를 만드는 진동 모드쌍을 측정하여 등가 종의 유한요소모델을 구성하였다. 등가 종 모델의 하부 두께를 국부적으로 감소시키면서 맥놀이의 변화를 해석적으로 구하였다. 해석 결과를 이용하여 선명하고 적절한 주기의 1차음 맥놀이를 만들었고, 힘차고 역동적인 소리를 내는 것을 실험적으로 확인하였다. The Great Bell of 2018 Pyeongchang Winter Olympics (Olympic Bell) was built to symbolize hope for the successful hosting of the 2018 Winter Olympics. Olympic Bell was designed to provide a dynamic sound at the world sports festival in the form of a traditional Korean bell shaped like a jar. For the dynamic sound of the bell, the beating sound should be clear and not too short or too long. However, beating was not predictable at the design stage because it was caused by the minute asymmetry in the casting process. After the casting, the beat period of the Olympic Bell was too long for the sound to be heard as desired. In this study, we improved the beat period using an equivalent bell model. A finite element model of the equivalent bell was constructed using the measured vibration modes that compose the beat. The change in beat period was analytically determined while gradually reducing the local thickness of the equivalent bell model. As a result, we created a strong and appropriate period of beat, and experimently confirmed that it produces powerful, dynamic sounds.

진동 맥놀이의 감쇠비 추정

김석현(Seockhyun Kim),변준호(Jun Ho Byeon) 한국소음진동공학회 2017 한국소음진동공학회 학술대회논문집 Vol.2017 No.10