In order to study the noise propagation characteristics and noise evaluation of military helicopters, this study conducted continuous noise monitoring of 20 noise-sensitive areas within 3 km around a military heliport in South Korea over a period of 5 days, and the results showed that the noise values at the 20 measurement points around the military heliport were lower than the limit of WECPNL 75 stipulated in the standard for civil airports, and it was found that the maximum noise level had the greatest influence on the evaluation indexes. The study found that the maximum noise level has the greatest influence on the evaluation index. At the same time, the analysis of the noise source spectrum shows that the helicopter noise is dominated by low and medium frequencies, and the low-frequency noise is more irritating in a short period of time.

본 연구에서는 해양플랜트 및 산업용 덕트에서 발생하는 유동 기인 소음을 저감하기 위해 다중공진구조 기반 광대역 소음기를 설계하고, 그 성능을 실험 및 수치해석으로 검증하였다. 제안된 소음기는 공진 특성이 다른 레이어를 주기적으로 배열해 1–3 kHz 구간에 서 국소 공진 차단대역과 Bragg 산란 밴드갭이 동시에 나타나도록 설계되었다. 음향해석 결과, 무유동 조건에서 약 50–60 dB의 삽입손실 이 확보되었으며, 유속 3 m/s와 9 m/s 조건에서도 10–25 dB의 감쇠 성능이 유지되었다. 실험과 수치해석은 전체 주파수 범위에서 정성적 으로 일치했으며, 고속 유동에서의 성능 저하는 공진기 목 주변의 난류 교란과 재생소음(regenerated noise) 영향으로 나타났다. 또한 Bragg 기반 밴드갭은 유동환경에서도 비교적 안정적으로 유지되어 구조적 차단 메커니즘이 성능 저하를 방지하는 데 기여함을 확인하였다. 본 연구는 흡음재 없이도 구조적 설계만으로 광대역 소음 제어가 가능함을 입증했으며, 향후 해양플랜트 및 산업용 덕트 설계 기준 마련에 기여할 수 있다.

Tire noise is one of major causes of vehicle noise, and urban traffic noise pollution is becoming more and more serious as the number of vehicles continues to increase. Especially in the age of electric vehicles, improvement of tire noise is getting more important. Especially during highway driving, the noise from the tire became the main noise source of the vehicle. Tire noise is generated from the mutual friction between the tire and the road surface when driving. In this paper, we analyze various factors affecting tire noise generation, reduce environmental noise pollution, and increase ride comfort. The EU carried out the EC 1222/2009 tire labeling system in 2012, which was a severe blow to the tire exporting countries of all countries due to the stringent demand for tire noise. In this paper, 5 tires from 3 countries were selected and selected as test subjects. The purpose of this study is to analyze the noise of road / tire noise according to road condition of each tire.

This study investigates hybrid propulsion for UAM & AAM as demand shifts toward short-range urban and suburban mobility enabled by advances in lightweight aircraft technologies. Urban low-altitude operations with frequent takeoffs and landings under stricter noise regulations require both high propulsion efficiency and low acoustic emissions. While electric propulsion provides precise controllability and low vibration, limitations in battery energy density and charging infrastructure constrain range, endurance, and turnaround. Hybrid propulsion can mitigate these constraints by combining the high energy density of fuel with the motor’s low-noise, fast-response operation. Accordingly, this study quantitatively compares thrust performance and noise spectra of an identical propeller when driven by an electric motor versus an internal combustion engine, providing baseline evidence to support hybrid propulsion system design.

소음성난청은 장기간의 소음 노출에 의해 누적적으로 진행되며, 일단 발병하면 회복이 어렵다는 특성이 있으므로 예방적 관리가 무엇보다 중요하다. 이러한 근로자 건강장해 예방을 위해 청력보존프로그램(Hearing Conservation Program)은 사업주가 수립하고 운영 해야 할 종합적인 관리 계획이며, 정부의 산업안전보건 정책에서도 청력보존프로그램의 수립 대상을 청력손실 가능성이 있는 모든 작업으로 확대하는 등 그 중요성이 지속적으로 강조되고 있다. 본 연구는 소음성난청 예방을 위한 청력보존프로그램의 실효성 확보를 위한 개선 방안을 제시하는 것을 목적으로 수행하였다. 이를 위해 학술 논문, 산재승인 현황, 작업환경측정 결과 등 사례 중심의 조사와 청력보존프로그램의 운영실태는 FGI 면담을 통해 분석하였다. 그 결과, 소음수준이 높은 사업장일수록 특수건강진단 결과에서 C1, D1 판정자의 분포가 높게 나타나 소음성난청 발생 위험이 있으며 현재 시행중인 청력 보존프로그램은 보호구 착용, 정기 건강진단에 치우쳐 있어 소음관리와 청력보존프로그 램의 실효성 확보는 시급한 과제임이 확인되었다. 이를 위해, 경영진의 정책적 지원, 근로 자의 참여, 관리감독자의 지속적인 관심을 포함한 종합적 운영이 필수적으로 프로그램의 각 단일요소의 실행이 아닌 “유해인자 확인(식별)→노출(위험)의 평가→조치(공학･관리 대책)→검토 후 피드백으로 구성된 PDCA 기반 통합순환 체계를 상호보완적으로 적용할 필요가 있다. 본 연구에서 제시한 실효성 확보방안은 근로자 청력 보호를 위한 정책적･실 천적 기초자료로 활용될 수 있을 것이며, 또한 기업의 ESG 경영요소 중 하나인 기업활동 의 리스크 관리와 책임경영에 도음이 될 것으로 기대된다. 향후 연구에서는 실제 산업현장 에 적용하여 효과를 비교･검증하고, 소음 수준별 맞춤형 대책을 구체적으로 제시하는 등 개선효과를 실증적으로 검증할 필요가 있다.

Priority should be considered to encourage businesses to participate by activating the low-noise machine certification system. However, the domestic low-noise machine certification system has not yet been significantly activated. There is a need for a system that only products that meet the environmental sign certification standards for low-noise construction machinery are recognized as "low-noise machines". A compliance evaluation agency (CAB) in the field of low-noise equipment should be introduced in Korea to help facilitate international certification of domestic company products. Therefore, it is believed that it will help expand the supply of low-noise machines through technology development and export improvement.

In recent years, airport construction projects have been promoted in island regions such as Gadeokdo, Baengnyeongdo, Ulleungdo, and Heuksando. However, a systematic review of the potential impact of aircraft noise transmitted underwater on marine life remains insufficient. This study acoustically analyzes the transmission process of airborne noise generated by aircraft as it passes through the sea surface and enters the underwater environment. The physical mechanisms are examined with a focus on transmission loss, conditions for total internal reflection, and acoustic impedance differences. In particular, the theoretical transmission coefficients of sound pressure and particle velocity at the air–water interface are reviewed and compared to the auditory reception ranges of marine organisms to assess the potential for acoustic impact. The findings of this study can serve as foundational data for establishing coastal and island airport noise management standards and formulating marine ecosystem protection policies.

This study investigated the operation status of major construction machines used in domestic construction sites and analyzed the characteristics of noise generated by these machines. In addition, we tried to understand the impact of construction machine noise on the working environment and the surrounding environment. As a result of the analysis, the noise level of the working breaker was the highest at 101.5 dB(A). This suggests that it can act as a major factor in the spread of noise to the residence around the construction site and the occurrence of civil complaints from residents. Therefore, this study is expected to provide a scientific basis for the noise problem of construction machinery and be used as basic data for effective noise management policies and system improvement.

This study examines the impact of Propeller blade pitch angle mismatch on Noise, thrust, and vibration in light aircraft. Tests were conducted using a simulator with one blade set at increased pitch angles (10°, 12°, 14°) compared to the standard 8°. Results showed that mismatches increased vibration (above 0.26 IPS), Noise levels, and caused operational issues such as fuel leakage and backfire. While thrust initially increased with pitch, it dropped at 14° due to fuel flow instability. These results highlight the need for strict pitch alignment tolerances to ensure optimal performance and safety in aircraft maintenance and operation.

Aircraft Noise is a sound that humans do not want. In this study, based on the Rotax 914 engine used in Korea, the Propeller blade angle was changed by 1 degree for the 3-leaf “K company” Propeller and the 3-leaf “G” wooden Propeller, and the engine RPM was changed to examine the Noise and thrust changes. The purpose of this study is to check whether Noise and thrust loss are the least at the engine's maximum RPM, and to propose an aircraft operation plan in the noisy aerodrome area based on the values. This research further seeks to identify optimal propeller configurations that balance acoustic performance and thrust efficiency. The results are expected to aid in formulating guidelines for quieter flight operations near populated areas.

Recently, among the newly developed cities, there has been a development of new towns around existing chemical manufacturing plants. Accordingly, the aim was to understand the impact of factory noise on the residential areas of the newly developed city. To this end, noise from the factories was measured in accordance with the noise measurement methods recommended by the Ministry of Environment, in order to assess the reality of factory noise sources. Additionally, to understand the impact of factory noise on nearby residential areas, noise maps were created and the noise reduction effects were investigated. The purpose of this study is to establish appropriate low-noise measures to address noise complaints around factories.

According to the results of the environmental noise measurement network operated by the Ministry of Environment in 2009, 67% of residential areas exceeded environmental standards during the day, and 82% exceeded during the night. In the case of exclusive residential areas in general districts, 30 cities (67%) exceeded the standards during the day, and 37 cities(82%) exceeded at night. For residential areas along roads, 18 cities(40%) exceeded during the day, and 33 cities(73%) exceeded at night. The Ministry of Environment operates noise and vibration measurement networks for environmental, railway, and aircraft noise, as well as road vibration measurement networks, to assess the noise and vibration status nationwide each year. In this regard, the results of measuring environmental noise in 348 areas across 45 cities nationwide last year showed that many cities in both general exclusive residential areas and residential areas along roads exceeded environmental standards both during the day(67% for general areas, 40% for road areas) and at night(82% for general areas, 73% for road areas). By region, cities such as Hwaseong, Pyeongtaek, Gimpo, and Cheongju showed high noise levels, while Mokpo, Namyangju, Seongnam, and Naju had lower noise levels. The regions with high noise levels were analyzed to reflect phenomena such as population and traffic increases due to regional development. This study aims to expand the noise measurement network in major cities of Jeollabuk-do, where there are relatively few measurement networks, by conducting an environmental noise survey on road traffic noise in Gunsan and Iksan, using it as basic data for establishing noise regulation zones and for the development of environmental noise reduction measures.

NVH(Noise, Vibration, and Harshness) characteristics are critical indicators for evaluating automotive quality and diagnosing mechanical issues through abnormal vibrations during driving. Among various components, tires are the only part of the automotive in direct contact with the road, making them a major source of noise and vibration. Tire-related anomalies not only affect ride comfort but can also pose serious safety hazards. This study presents a diagnostic approach that utilizes NVH analysis, wheel balance inspection, and RFV(Radial Force Variation) measurement to identify and repair tire faults. Through case analysis, it was confirmed that abnormal vibrations caused by internal moisture accumulation and structural deformation of tires could be accurately diagnosed and addressed. The proposed method enables early detection of tire-related issues, providing a preventive maintenance strategy and contributing to enhanced automotive safety and reliability.

As conventional road traffic noise prediction models are designed to estimate long-term representative noise levels, capturing fine-scale noise fluctuations caused by real-world traffic dynamics is challenging. A previous study proposed a microscopic road traffic noise model (MTN) can calculate time-series noise levels with a resolution of 1 s using the concept of a moving noise source. In this study, two experiments were conducted to verify the accuracy of the noise prediction of the model. First, by comparing the calculated noise levels of two conventional road traffic noise models and the MTN in a simple road simulation environment, it was confirmed that the calculation error was within 3 dB(A) when calculating the 1-h equivalent noise level. Second, an experiment was conducted to verify the noise prediction error of the MTN on six actual roads. A comparison of the calculated noise level using the MTN based on traffic data collected from actual roads with the measured noise level on real roads showed that the calculated noise level achieved a mean absolute error (MAE) of 1.88 dB(A) from the equivalent noise level and 1.28 dB(A) from the maximum noise level. This was similar to the MAE of the foreign road traffic noise models. However, when the location of the receiver is within 10 m of the road, an error of more than 3 dB(A) occurs because of the simplicity of the MTN propagation model, which remains a problem that must be solved in the future. This study proved that the noise level calculation using the MTN is similar to the noise of an actual road environment. Additionally, the continuous development of the MTN is expected to make it an effective alternative for the management of road noise.

Baengnyeong Airport is under review for construction to improve transportation accessibility in island regions and has passed the preliminary feasibility study. While airport development significantly enhances transportation convenience for residents, it may also cause aircraft noise issues and lead to conflicts within local communities. Previous studies estimated noise impacts based on ATR-42 and Q300 aircraft. However, this study focuses on a more realistic assessment using ATR-72 and E190-E2 aircraft. By utilizing the FAA’s Aviation Environmental Design Tool (AEDT), a projected noise contour map for Baengnyeong Airport was developed. The analysis shows that considering ATR-72 and E190-E2, which generate higher noise levels, provides a more practical evaluation of noise-affected areas. The results indicate that the noise impact is mostly confined within the runway area; however, potential noise complaints may arise from Baengnyeong Island and nearby regions. Based on these findings, this study suggests the need for optimized flight procedures and urban planning measures to mitigate aircraft noise issues.

Ulsan Airport cannot operate precision instrument approach procedures from the south direction (Runway 18) due to obstacles. Even non-precision instrument approach procedures have higher approach angles and minimum descent altitudes (MDA) compared to other airports, which can pose safety risks for pilots following the flight procedures. Recently, since the introduction of SBAS-based satellite navigation flight procedures in Korea, Ulsan Airport is expected to experience improvements, including reduced offsets and lower minimum descent altitudes in its existing flight procedures. During the design process of new flight procedure routes, a comprehensive analysis of noise differences from existing routes and the noise impact on new areas is necessary. Therefore, this study aims to present the changes in aircraft noise resulting from the implementation of new flight procedures using the Aviation Environmental Design Tool (AEDT)

본 연구의 목적은 복층 배수성·저소음 아스팔트 포장의 공용수명 예측과 경제성 분석에 있다. 성능평가를 위한 현장시 험은 투수시험 및 소음 측정을 실시하였으며, 실내시험은 반사균열, 동탄성계수, 소성변형(FN) 시험을 진행하였다. 성능 평가 결과를 기반으로 포장설계 수명 예측 및 비용 편익 분석을 수행하였으며, 이를 일반 밀입도 포장의 비용 편익과 비 교·분석하여 복층 배수성·저소음 아스팔트 포장의 경제성을 확인하고자 하였다. 성능평가 결과 복층 배수성·저소음 포장 이 일반 밀입도 포장과 비교 시 소음 저감 성능에서 매우 우수한 결과를 나타내었다. 비용 편익 분석 결과 복층 배수성· 저소음 아스팔트 포장은 높은 초기비용에도 불구하고 설계기간동안 낮은 유지보수 비용을 가지며 안전 및 소음 측면에 서 일반 밀입도 포장과 비교 시 매우 경제적인 것으로 나타났다. 총 비용과 총 편익 비용을 편익 비용 비율(BCR)로 계 산한 결과 복층 배수성·저소음 아스팔트 포장이 단위 비용 당 편익 측면에서 방음벽이 있는 다른 포장에 비해 가장 우수 한 결과를 보였다.

I would like to suggest a solution to the problem of aircraft battalion helicopter noise complaints. Among the noise evaluation units, the unit that meets the military helicopter noise evaluation is analyzed and selected to scientifically and reasonably resolve the conflict between residents in the neighboring area and the aviation battalion. Helicopter noise is one of the important problems causing pollution in various pollution problems in the area around the aircraft battalion. The rational and planned process of aircraft battalions will be a way to address aircraft noise pollution.

Automotive technology has developed rapidly and is becoming the intensive of cutting edge technology. For this reason, Automotive are used not only as a means of transportation, but also as a private and leisure spaces. The driver wants to keep quiet even if the car is used for a long time. NVH should be reduced because it is caused by mechanical defects and aging. In this study, it was presented that a seven-step procedure for failure diagnosis and repair to reduce noise/vibration. NVH was diagnosed by comparing the result of the rotator order tracking analysis with the problem frequency. It was possible to accurately analyze the cause of noise and vibration, also it coud identify the location, and repair that.