• The Journal of the Acoustical Society of Korea
• /
• 제42권6호
• /
• pp.565-571
• /
• 2023

With the introduction of the post-verification system, the measurement of floor impact noise performance on-site has become mandatory, and the evaluation method has changed. To track the performance changes since the policy implementation, research is needed on how the characteristics of heavyweight impact sound change according to the varied evaluation method. In this study, we analyzed the contribution rate of the frequency band-specific sound pressure level on the single-number quantity for a multi-family housing unit with the same floor plan and floor structure, comprising 59 households, based on the changed impact sources and evaluation indicators. It is difficult to compare simply because the method of calculating contributions by frequency band according to the single-day evaluation is different, but the average contribution rate of 63 Hz was 80.8 % in the evaluation method before the introduction of the post-confirmation system (Tire measurement and evaluated as L'_i,Fmax,AW), and the average contribution rate of 125 Hz was 19.2 %. The current evaluation method (rubber ball measurement and evaluation as L'_iA,Fmax) shows that the contribution rate has decreased to 33.1 % on average at 50 Hz ~ 80 Hz, 58.7 % on average at 100 Hz ~ 160 Hz, 6.9 % on average at 200 Hz ~ 315 Hz, and 1.3 % on average at 400 Hz ~ 630 Hz. This result is a case analysis for the target apartment house, and it is necessary to analyze measurement data for more diverse apartment houses.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
• /
• pp.633-638
• /
• 1988

In this paper, a zero-velocity update technique to improve navigation accuracy of a SDINS(Strapdown Inertial Navigation System) has been studied. An indirect feedback Kalman filter which includes SDINS error equations based on a quaternion between body-fixed frame and local level navigation frame is employed for processing zero-velocity updates in an on-board navigation filter. Simulation results for land-mobile vehicle show that the zerovelocity update technique make a significant contribution to improving SDINS performance without any external aids.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제21권6호
• /
• pp.592-602
• /
• 2020

This study examined the contribution of the risk factors that cause cardiovascular disease in Koreans. The subjects were 20,012 adults aged 30~74 years who were enrolled from the 2005~2013 Korean National Health and Nutrition Examination Survey, had filled the risk factors data, and had no cardiovascular disease history. Data analysis was conducted using SAS 9.3, and a weighted composite sample design analysis was performed. The contribution was obtained by applying a squared semi-partial correlation. As a result, they were higher in the order of age (63.9%), smoking (17.3%), systolic blood pressure (7.9%), diabetes (6.9%), antihypertensive medication use (3.0%), and BMI (0.9%) in men. In women, the contributions were in the order of age (54.1%), systolic blood pressure (23.5%), diabetes (13.6%), antihypertensive medication use (5.1%), smoking (3.1%), and BMI (0.6%%). According to age bracket analysis, smoking (51.8~33.7%) was the biggest risk factor, followed in order by age (26.6%) in their 30s and systolic blood pressure (17.3~21.0%) in those older than 40 years in men. In women, the systolic blood pressure (56.2~40.5%) was the main contributor to the risk factors, followed by age (24.0%) in their 30s and diabetes (13.6~32.6%) in those older than 40 years. The contribution of the income level was similar. Therefore, to prevent cardiovascular disease, various programs that reflect the contributions of the risk factors should be developed. Moreover, it is recommended to use the results shown in this study as basic data.

• Korean Journal of Organic Agriculture
• /
• 제19권spc호
• /
• pp.242-246
• /
• 2011

Organic kiwifruit orchard soils were compared with conventional ones in Korea. Soil structure of organic soil had higher gaseous and liquous phase as well as soil porosity in the surface soil. Although the nutritional level of each orchards were quite different among soils, the analysis of both system revealed that organic kiwifruit orchard soil had similar or even higher nutrient level (N and organic matter content in surface soil) compared to conventional ones. The organic matter content of deep soil also had the high tendency in deep soil of organic soil. Higher level of nitrogen in organic surface soil is presumably due to the excessive application of organic compost and liquid fertilizer rather than the contribution by grasses such as green manure. Available phosphorous level of organic system was quite high but similar in surface soil of both system, compared to the recommended level. Potassium, calcium and magnesium levels were also enough in organic kiwifruit orchard soils.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 한국대기환경학회 2010년도 춘계학술대회 논문집
• /
• pp.451-453
• /
• 2010

• Journal of Environmental Health Sciences
• /
• 제45권6호
• /
• pp.630-637
• /
• 2019

Objectives: This study was performed to evaluate the secular changes in indoor airborne dust or endotoxin levels in the dust from swine confinement buildings. Indoor levels were compared with the level at the exhaust outlet in order to examine the contribution potential of indoor dust to nearby ambient air dust. Methods: Comparisons were made on inhalable and respirable dust levels reported in 2002, 2012, and 2017 from 14, 10, and 36 swine fattening confinement buildings in Korea, respectively. This data was produced by the same research group. Levels of endotoxin adsorbed into inhalable or respirable dust were also compared. Samples of inhalable or respirable dust were collected indoors and at exhaust outlets from 17 swine fattening confinement buildings in 2019, and dust levels were compared between the indoor and the outlet. Results: The outlet inhalable dust level (0.111 mg/㎥) was approximately 19% of that from indoors, and the respirable dust level (0.033 mg/㎥) was approximately 74% of that from indoors. The outlet respirable dust levels were lower than the airborne fine dust levels in the towns where those farms are located. No significant difference was observed in the inhalable dust levels among the years examined, but the respirable dust level in 2017 (0.143 mg/㎥) was significantly lower than in 2002 (0.328 mg/㎥). The level of endotoxin in inhalable dust was significantly higher in 2017 (722 EU/㎥) than in both 2002 (75 EU/㎥) and 2012 (171 EU/㎥). Conclusion: Even though no apparent contribution from swine farm indoor dust to nearby ambient air dust was observed in terms of amount, a certain control strategy to reduce the production of airborne dust and endotoxin from swine farms is merited.

• Earthquakes and Structures
• /
• 제23권3호
• /
• pp.271-282
• /
• 2022

Seismic resisting self-centering bridge piers with high energy dissipation and negligible residual displacement after an earthquake event are focus topics of current structural engineering. The energy dissipation components of typical bridge piers are often relatively single; and exhibit a certain level of damage under earthquakes, leading to large residual displacements and low cumulative energy dissipation. In this paper, a novel socket self-centering bridge pier with a hybrid energy dissipation system is proposed. The seismic resilience of bridge piers can be improved through the rational design of annular grooves and rubber cushions. The seismic response was evaluated through the finite element method. The effects of rubber cushion thickness, annular groove depth, axial compression ratio, and lateral strength contribution ratio of rubber cushion on the seismic behavior of bridge piers are systematically studied. The results show that the annular groove depth has the greatest influence on the seismic performance of the bridge pier. Especially, the lateral strength contribution ratio of the rubber cushion mainly depends on the depth of the annular groove. The axial compression ratio has a significant effect on the ultimate bearing capacity. Finally, the seismic design method is proposed according to the influence of the above research parameters on the seismic performance of bridge piers, and the method is validated by an example. It is suggested that the range of lateral strength contribution ratio of rubber cushion is 0.028 ~ 0.053.

• Bulletin of the Korean Chemical Society
• /
• 제32권2호
• /
• pp.583-589
• /
• 2011

Fluorescence correlation spectroscopy (FCS) is a sophisticated and an accurate analytical technique used to study the diffusion of molecules in a solution at the single-molecule level. FCS is strongly affected by many factors such as the stability of the excitation power, photochemical processes, mismatch between the refractive indices, and variations in the cover glass thickness. We have studied FCS near the surface of a cover glass by using rhodamine 123 as a fluorescent probe and have observed that the surface has a strong influence on the measurements. The temporal autocorrelation of FCS decays with two characteristic times when the confocal detection volume is positioned near the surface of the cover glass. As the position of the detection volume is moved away from the surface, the FCS autocorrelation becomes one-component decaying; the characteristic time of the decay is the same as the faster-decaying component in the FCS autocorrelation near the surface. This observation suggests that the faster component can be attributed to the free diffusion of the probe molecules in the solution, while the slow component has its origin from the interaction between the probe molecules and the surface. We have characterized the surface contribution to the FCS measurements near the surface by changing the position of the detection volume relative to the surface. The influence of the surface on the diffusion of the probe molecules was monitored by changing the chemical properties of the surface. The surface contribution to the temporal autocorrelation of the FCS strongly depends on the chemical nature of the surface. The hydrophobicity of the surface is a major factor determining the surface influence on the free diffusion of the probe molecules near the surface.

• Journal of Korean Society on Water Environment
• /
• 제37권4호
• /
• pp.249-262
• /
• 2021

This study investigated the pollution characteristics of the main pollution zone in the Hwangguji watershed and the influence of the tributary on the main stream. The characteristics of the main pollution zone, including, the water quality index (WQI), stream rating, load duration curve (LDC), delivery load density (DLD), and contribution of the tributary to the mainstream, were evaluated by time-series visual heatmap. The WQI of the mainstream of Hwangguji was lowered to the poor (IV) level from the inflow point of Suwon stream (SW) and the LDC excess rate in the T-P was higher than that of BOD₅, especially for the wet season, suggesting that management of non-point source with T-P is preferred. The contribution (%) of the tributaries in the upstream section of Hwangguji watershed were BOD₅ 14.54%, TOC 15.67%, T-N 5.43%, and T-P 6.97%. In particular, the Suwon sewage treatment plant located in the mainstream showed a high contribution of BOD₅ (64.40%) and T-P (53.54%), respectively, due to the high discharge rate (6.019 m³/sec). Meanwhile, Sammi and Gal stream have a large impact on the mainstream with high DLD and poor WQI. Thus, both streams were considered as pollution hot spots. These results provide useful basic data for preparing more effective water quality improvement and management plans in the watershed.

• Journal of Family Relations
• /
• 제22권3호
• /
• pp.47-72
• /
• 2017

Objectives: Do husbands with working wives share domestic labor more equally than husbands with unemployed housewives? Is the husband's contribution sufficient enough to satisfy his wife? These questions have long inspired many researchers to find ways to more accurately estimate husband's domestic contributions and narrow the emotional gap following the different threshold of satisfaction within couples, but not without some limits. This study attempted to figure out an answer to the above-mentioned subject by using time diaries of Korean married couples with a preschooler as their first-born child and relying on the typology of husbands' sharing of housework and childcare, which allowed me to overcome some limitations of prior research. Method: I analyzed a total of 1,716 diaries of 858 married couples from 2014 Korea Time Use Survey with descriptive statistics, t-test, cluster analysis, and multinomial logit. Results: Analytic results showed that husbands in dual-earner households did share domestic labor more equally than husbands in single-earner households, but there were different types of husband's contribution depending on time they spent in housework and childcare. While more than half of husbands with employed wives shared more or less than ten percent of domestic labor, the rest were divided into one group of husbands who shared both housework and childcare more heavily and evenly, and another group who were mainly involved in childcare duties. It is interesting that husbands who made the least contributions to domestic labor were not the ones with the lowest level of satisfaction with their sharing of household labor, whereas their wives were deeply dissatisfied, leading to a huge emotional gap within couples. Conclusion: Identifying factors associated with the three different types allowed me to find a point of intervention to narrow the emotional gap that is likely to harm the marital relationship if left unattended to.