http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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.
이중혁(Joong-hyeok Lee),김석현(Seock-hyun Kim) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.4
This study proposes an equivalent bell model for the Sacred Bell of the Great King Seongdeok. An equivalent bell model has the modal property of the real bell and it consists of an axi-symmetric bell body and a point mass. The bell model is constructed by the finite element analysis based upon the theory of a revolutionary shell. Using the equivalent bell model, the beat period can be controlled by decreasing the thickness of local area. This study aims at showing a beat period control method for a large bell having the similar size to the Sacred Bell of the Great King Seongdeok.
이중혁(Joong Hyeok Lee),안용찬(Yong Chan Ann),김석현(Seock Hyun) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.5
Since opening of the double track railway for the Gyeongchun local electric train and the semi-high speed train, ITX, floating population between Seoul and Chuncheon has rapidly increased. This is attributable to the competitiveness of the railway vehicle in aspect of punctuality and safety of the operation, mass transportation and low fare. However, in terms of the interior noise, many passengers have a strong dissatisfaction, especially in tunnel sections, and displeasure according to the high interior noise rapidly increases. In this study, interior noise characteristics of Gyeongchun local electric train and ITX are analyzed and compared- Noise levels, frequency spectrum and sound quality indices are compared between the open land, tunnel and bridge. By comparing the noise levels depending on the location in the compartment, we identify the noise transmission path and provide a basic strategy to reduce the interior noise.
통계적 에너지 해석법을 이용한 차세대 고속철도 차량의 실내 소음 해석
이중혁(Joong Hyeok Lee),김석현(Seock Hyun Kim),김정태,김태민(Tae Min Kim) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
In this study, the interior noise of the next generation high-speed train (HST) is analysed by using the statistical energy analysis (SEA) method. Exterior sound level data are used as input and for the sound transmission loss of each panel, intensity transmission loss is measured based on ASTM E2249-02. For the interior acoustic property, reverberation time of the passenger compartment is measured. Finally, interior noise level is measured in a running train at 350㎞/h in order to verify the validity of the simulation result.
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.
이중혁(Joong Hyeok Lee),변준호(Jun Ho Byeon),이재준(Jae Joon Lee),김석현(Seockhyun Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-
Unitex structure is world is world widely used for floor panel of the most of the electrical trains. It has advantage of high bending stiffness per weight and fire retardant property and easy construction with low cost. In respect of sound insulation, however, it has limitation as the panel structure has a lot of small pores and significant leakage of the sound power is available through the pores. In this study, we estimate the sound insulation performance the core of the unitex structure and investigate the problem of the sound insulation. Intensity transmission loss is measured on the manufactured specimens according to ASTM E2249-02. Based on the measured data and mass law values, a strategy to improve the sound insulation performance of the structure is proposed.
김석현,이중혁,Kim, Seock-Hyun,Lee, Joong-Hyeok 한국음향학회 2012 韓國音響學會誌 Vol.31 No.8
본 연구는 등가 종 모델을 이용하여 한국종의 맥놀이 주기를 조절하는 방법을 제시한다. 한국종이 갖고 있는 미세한 비대칭성은 하나의 원주 모드를 미세한 주파수의 차이를 갖는 모드 쌍으로 분리시키는데, 이 모드 쌍의 상호간섭에 의해서 진동과 음향의 맥놀이가 발생한다. 등가 종은 축대칭 종에 등가 집중질량을 부착시킨 미소 비대칭 구조물로, 실제 종의 모드 쌍과 동일한 모드 특성을 갖는다. 등가 종 모델은 회전 쉘 이론을 근거로, 유한요소해석을 통해서 구성된다. 맥놀이 특성을 변화시키기 위하여 국부적으로 요소 두께를 감소시킬 때, 등가 종을 이용하여 맥놀이 주기를 예측한다. 예측 결과는 시험 종에 대한 실험을 통해 그 타당성을 확인한다. 본 방법은 대형 종의 맥놀이 주기 조절에 소요되는 시간을 크게 줄일 수 있을 것이다. This study proposes a method of an equivalent bell model in order to tune the beat period of a Korean bell. In a Korean bell having a slight asymmetry, each circumferential mode splits into a mode pair which has a slight difference in frequency, and the interaction of the mode pair makes a beat in vibration and sound. An equivalent bell model which consists of an axi-symmetric bell and an equivalent point mass, has the same mode property as in a real bell. The equivalent bell model is constructed by the finite element analysis based upon the theory of a revolutionary shell. Using the equivalent bell model, the beat period is predicted when the bell thickness is locally decreased to improve the beat property. The predicted result is verified by experiment on a test bell. The proposed method is useful to save the time required for tuning the beat period of a large bell.