PURPOSES : The tire-pavement interaction noise (TPIN) comprises four sources, among which the tire tread vibration noise (TTVN) and air pumping noise (APN) are known to be the most influential. However, when evaluating TPIN, the noise level is estimated based on the overall noise, because general noise measurement methods cannot separate TTVN and APN. Therefore, this study aims to develop a method to separate TTVN and APN in TPIN for quantitative assessment of pavement noise. METHODS : Based on the results of our literature review and frequency band noise data measured in our study, we identified the dominant frequency ranges for TTVN and APN. Additionally, we evaluated TTVN and APN across various pavement types. RESULTS : TTVN was found to be dominant in frequency bands below 800 Hz, while APN was dominant in frequency bands above 800 Hz. Additionally, regardless of the vehicle type, vehicle speed, or pavement type, APN exhibited higher levels compared to TTVN. This result shows that APN has a more significant impact on TPIN than TTVN. CONCLUSIONS : The separation method of TTVN and APN proposed in this study can be utilized to quantitatively assess the relationship between the primary noise sources in TPIN and the characteristics of pavement texture in future research. Furthermore, it is anticipated that characteristics of low TPIN and optimal texture conditions can be proposed to mitigate TPIN, thus contributing to the development of lownoise pavements.

Background: Self-myofascial release using a foam roller has short-term effects for improving muscle function and joint range of motion (ROM) and reducing delayed onset muscle soreness (DOMS) after exercise. Objectives: The purpose of our study was to examine the muscle physiological changes for each set in self-myofascial release of the hamstring muscles using a foam roller in order to provide basic data for the most effective program composition for improving muscle tension, stiffness, and flexibility of the hamstring muscles. Design: A quasi-experimental clinical trial. Methods: To confirm the effect of self-myofascial release of the hamstring muscles using a foam roller, muscle tone and stiffness of the hamstring muscles were measured. As an intervention method, the study subject performed four sessions of self-myofascial release by moving a foam roller back and forth on the posterior thigh muscle of the right leg. Results: There were statistically significant changes in the stiffness of the biceps femoris and the flexibility of the hamstring muscles. Conclusion: Self-myofascial release with foam rolling is an effective intervention method for increasing hamstring flexibility and ROM, and it is recommended as effective to perform self-myofascial release for three to four sessions to maintain normal muscle tone and stiffness of the hamstring muscles.

In this research, we examined the shifts in determinants influencing the frequency of eco-friendly food purchases pre- and post-COVID-19. Our analysis utilized filtered 2019-2021 Consumption Behavior Survey data from the Korea Rural Economic Institute Food, excluding any irrational responses. Given the nature of the dependent variable, a multinomial logistic regression model was employed with demographic factors, variables pertaining to food consumption behavior, and variables concerning food consumption awareness as predictors. Following the onset of the COVID-19 pandemic, an individual's level of education was observed to positively influence the frequency of eco-friendly food purchases. In contrast, income level and fluctuations in food consumption expenditure did not appear to have a discernible impact on the purchasing frequency of such eco-friendly products. Irrespective of the advent of COVID-19, variables such as the frequency of online food purchases, the utilization of early morning delivery services, dining out frequency, and the intake of health-functional foods consistently demonstrated a positive correlation with the propensity to purchase eco-friendly foods. Overall, consumers prioritizing safety, quality, and nutrition over price, taste, and convenience in their procurement decisions for rice, vegetables, meat, and processed foods exhibit an increased inclination toward the acquisition of eco-friendly food products.

본 논문에서는 볼트로 체결된 구조체에 대하여 초기 볼트풀림 상태에서의 볼트 체결력 예측 합성곱 신경망 훈련 방법을 제시한다. 8개의 볼트의 체결력이 변경된 상태에서 계산한 주파수응답들을 완전 체결된 상태의 초기 모델과의 크기 및 모양 유사성을 표현하는 유사성 지도로 생성한다. 주파수응답 데이터들의 생성에는 크리로프 부공간법 기반의 모델차수축소법을 적용하여 효율적인 방법으 로 수행할 수 있도록 한다. 합성곱 신경망 모델은 회귀 출력 계층을 사용하여 볼트의 체결력을 예측하도록 하였으며, 훈련 데이터의 개 수와 합성곱 신경망 계층의 개수를 다르게 준비하여 훈련시킨 네트워크들을 비교하여 그 성능을 평가하였다. 주파수응답에서 파생되 는 유사성 지도를 입력 데이터로 사용하여 초기 볼트풀림 영역에서 볼트 체결력의 진단 가능성과 유효성을 제시하였다.

This study applied the text frequency method to analyze the crops prevalent during the Chosunwangjoshilrok dynasty, and categorized the results by each king. Contemporary perception of grains was observed by examining the staple crop types. Staple species were examined using the word cloud and semantic network analysis. Totally, 101,842 types of crop consumption were recorded during the Chosunwangjoshilrok period. Of these, 51,337 (50.4%) were grains, 50,407 (49.5%) were beans, and 98 (0.1%) were seeds. Rice was the most frequently consumed grain (37.1%), followed by pii (11.9%), millet (11.3%), barley (4.5%), proso (0.8%), wheat (0.6%), buckwheat (0.1%), and adlay (0.05%). Grain chronological frequency in the Choseon dynasty was determined to be 15,520 cases in the 15th century (30.2%), 11,201 cases in the 18th century (21.8%), 9,421 cases in the 17th century (18.4%), 9,113 cases in the 16th century (17.8%), and 6,082 cases in the 19th century (11.8%). Interest in grain amongst the 27 kings of Choseon was evaluated based on the frequency of records. The 15th century King Sejong recorded the maximum interest with 13,363 cases (13.1%), followed by King Jungjo (8,501 cases in the 18th century; 8.4%), King Sungjong (7,776 cases in the 15th century; 7.6%).

Controller modeling is essential for the design. It allows various control techniques to be simulated in advance, and various interpretations can be performed. If this is not the case, we need to reverse engineering in the real system developed by others. In this paper, controller modeling was reversely designed using the frequency test results of the target system. First, the characteristic equation of the target equipment was based on and a block diagram was assumed. Thereafter, controller variables were estimated using the frequency test results for each of the four control loops. In addition, time response simulations were performed using the estimated controller modeling. This method is thought to be of great help to reverse engineering in situations where there is completed equipment but no controller modeling.

본 연구에서는 우리나라에 태풍이 내습할 때 먼저 피해를 받는 남해안 지역을 대표하는 Quantile을 제안하고, 각 지점들의 재 현기간에 따른 극치 풍속을 추정하기 위하여 연 최대풍속 자료와 Hosking이 제안한 선형-모멘트 방법(L-moments)을 이용한 지역빈도 해석을 수행하였다. 모든 기상관측 지점에서는 비정상적인 값이 존재하지 않았고 이질성 검정을 통해서 하나의 동질 한 지역을 나타 낼 수 있음을 확인하였다. 또한 적합도 과정을 통해서 Generalized Normal (GNO) 및 Generalized Extreme Value(GEV) 분포를 남해안 지역을 대표하는 빈도분포로 선택하였다. 상대 오차(RB)와 상대 평균제곱근 오차(RRMSE)를 이용하여 두 분포의 안정성을 평가한 결 과, GNO 분포가 GEV 분포보다 더 안정한 것을 알 수 있었다. 마지막으로 남해안 지역을 대표하는 Quantile과 각 지점들의 평균, 중앙 값, 그리고 위치 매개변수를 이용하여 지점들의 극치 풍속을 추정하였다. 본 연구에서 적용한 지역빈도해석이 자료가 부족하거나 계측 되지 않은 지점들에 대한 극치 풍속을 추정하기 위한 방법으로서 도입이 필요하다고 생각된다.

In September and October 2020, combined acoustic and trawl surveys were conducted in the northwestern sea of Jeju Island. In the survey area, a region, so called Jeju region, was designated to esimate the biomass of chub mackerel and jack mackerel using a trawl survey method and frequency difference method. In the September survey, the weight ratios of jack mackerel and chub mackerel to the total catch were 24.6% and 2.8%, respectively, and in the October survey, those ratios were 24.9% and 20.7%, which were used to calculate their biomass (trawl survey). Using the frequency difference range (–8 to –3dB) corresponding to two species in 120 and 200 kHz, their biomass was estimated (frequency difference method). As a result, the biomass of two species from the trawl method was 3252.3 tons in September and 5777.0 tons in October. The estimated biomass by the frequency difference method was 4926.6 tons in September and 7521.5 tons in October. It was the first trial to estimate the biomass of two species using the trawl and frequency differencing methods in South Korea although there were some differences between two methods. In addition, horizontal distributions of acoustic backscattering strength over the entire survey area were mapped.

Seismic qualification of instruments and devices mounted on electrical cabinets in a nuclear power plant is performed in this study by means of the in-cabinet response spectrum (ICRS). A simple method and two rigorous methods are proposed in the EPRI NP-7146-SL guidelines for generating the ICRS. The simple method of EPRI can give unrealistic spectra that are excessively conservative in many cases. In the past, the time domain analysis (TDA) methods have been mostly used to analyze a structure. However, the TDA requires the generation of an artificial earthquake input motion compatible to the target response spectrum. The process of generating an artificial earthquake may involve a great deal of uncertainty. In addition, many time history analyses should be performed to increase the accuracy of the results. This study developed a numerical analysis program for generating the ICRS by frequency domain analysis (FDA) method. The developed program was validated by the numerical study. The ICRS calculated by FDA thoroughly matched with those obtained from TDA. This study then confirms that the method it proposes can simply and efficiently generate the ICRS compared to the time domain method.

To understand the genesis of tropical cyclones (TC), we computed TC genesis probability (GPr) by partitioning a highly localized genesis frequency (GFq) into nearby grid boxes in proportion to the spatial coherence of genesis potential index (GPI). From the analysis of TCs simulated by the Seoul National University Atmosphere Model Version 0 and the observed TCs, it was shown that GPr reasonably converges to GFq when averaged over a long-term period in a decent grid size, supporting its validity as a proxy representing a true TC GPr. The composite anomalies of the gridded GPr in association with the Asia summer monsoon, El Nino-Southern Oscillation (ENSO), and the Madden-Julian Oscillation (MJO) are much less noisy than those of GFq, and consequently are better interpretable. In summary, GPr converges to GFq, varies more smoothly than GFq, represents the spatiotemporal variations of GFq better than GPI, and depicts GFq with greater spatial details than other spatially smoothed GFqs.

Information and communication technologies are developing rapidly as IC chip size becomes smaller and information processing becomes faster. With this development, digital circuit technology is being widely applied to mobile phones, wireless LANs, mobile terminals, and digital communications, in which high frequency range of GHz is used. In highdensity electronic circuits, issues of noise and EMC(Electro-Magnetic Compatibility) arising from cross talk between interconnects or devices should be solved. In this study, sheet-type electromagnetic wave absorbers that cause electromagnetic wave attenuation are fabricated using composites based on soft magnetic metal powder and silicon rubber to solve the problem of electromagnetic waves generated in wireless communication products operating at the frequency range of 2.4 GHz. Sendust(Fe-Si-Al) and carbonyl iron(Fe-C) were used as soft magnetic metals, and their concentrations and sheet thicknesses were varied. Using soft magnetic metal powder, a sheet is fabricated to exhibit maximum electromagnetic attenuation in the target frequency band, and a value of 34.2dB(99.9 % absorption) is achieved at the target frequency.

In the present work, spheroidization of angular vanadium powders using a radio frequency (RF) thermal plasma process is investigated. Initially, angular vanadium powders are spheroidized successfully at an average particle size of 100 μm using the RF-plasma process. It is difficult to avoid oxide layer formation on the surface of vanadium powder during the RF-plasma process. Titanium/vanadium/stainless steel functionally graded materials are manufactured with vanadium as the interlayer. Vanadium intermediate layers are deposited using both angular and spheroidized vanadium powders. Then, 17-4PH stainless steel is successfully deposited on the vanadium interlayer made from the angular powder. However, on the surface of the vanadium interlayer made from the spheroidized powder, delamination of 17-4PH occurs during deposition. The main cause of this phenomenon is presumed to be the high thickness of the vanadium interlayer and the relatively high level of surface oxidation of the interlayer.