• Proceedings of the Acoustical Society of Korea Conference
• /
• 1994.06c
• /
• pp.125-128
• /
• 1994

선형예측기법으로 피치동기식 분석을 하기 위해 우선적으로 필요한 정보로서 유성음 신호의 영교차 구간별 평균 진폭변동율 추출에 의한 주기별 피치를 검출할 수 있는 기법을 제안하였다. 유성음의 제1포먼트 성분에 대한 각 영교차 구간에서의 평균진폭값은 성대 폐쇄시점에서 주기별 최대치를 나타내며, 평균진폭변동율은 "+" 영역의 평균진폭값과 선행하는 "-" 영역 값의 차로 표시한다. 이 평균 진폭 변동율은 성대파형의영향이 반영되어 주기성이 더욱 강조되므로 분석구간에 대한 구간별 평균피치와 변화의 정도를 이용하여 주기별피치정보를 추출할 수 있다. 검출결과는 구간별 평균피치와 비교하였으며, 좋은 결과가 나타나는 것을 확인할 수 있다.과가 나타나는 것을 확인할 수 있다.

• Water for future
• /
• v.18 no.1
• /
• pp.67-73
• /
• 1985

Tidal propagation in the Keum River has been routinely handled by numerical integration of the long fravity wave equation by Dronkers. The dynamic equations include non-linear terms thereby reproducing the shallow water tides. The model was used to compute tidal distribution of the Kum River for aveage spring, mean, neap tidal conditions and further utilised to investigate the waterlevel response within tidal reaches by combined tide and flood discharge effects. The objective of this initial study is to investigate the tidal dynamics of the lower reaches of the Keum River under the condition of before-cross-channel barrage construction.

• Land and Housing Review
• /
• v.13 no.4
• /
• pp.73-89
• /
• 2022

With the spread of COVID-19, the role of parks has been emphasized. Under the quarantine guidelines, including social distancing, people are visiting parks as a safe place. In line with these changes, parks need to be studied as pandemic adaptation measures according to their physical and location characteristics. This study aims to explore the potential of linear parks with accessibility and pass way functions based on the characteristics of surrounding land uses. The case study area was selected from Yeonnam-dong to Yeomni-dong of the Gyeongui Line Forest Park, and the area was divided into 4 sections based on the administrative boundary and surrounding land uses. Multiple regression models were adopted in each section using the total number of de facto population as a dependent variable and factors affecting external activities including COVID-19 as independent variables. The results show that first, the more diverse the interaction between commercial facilities and linear parks, the greater the impact of the pandemic. Second, where various commercial facilities are concentrated people respond more sensitively to short-term weather changes than seasonal ones. This study indicates that there are differences in the use of linear parks according to the surrounding land uses. In addition, it suggests that the linear park has potential as a means to overcome the Pandemic crisis of the city and to increase equity in access to green areas.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.33 no.6
• /
• pp.257-264
• /
• 2021

This study established a numerical model capable of calculating the wave overtopping rate of coastal structures by nonlinear irregular waves using the FUNWAVE-TVD model, a fully nonlinear Boussinesq equation model. Here, a numerical model was established by coding the mean value approach equations of EurOtop (2018) and empirical formula by Goda (2009), and adding them as subroutines of the FUNWAVE-TVD model. The verification of the model was performed by numerically calculating the wave overtopping rate of nonlinear irregular waves on vertical wall structures and comparing them with the experimental results presented in EurOtop (2018). As a result of the verification, the numerical calculation result according to the EurOtop equation of this model was very well matched with the experimental result in all relative freeboard (R_c/H_mo) range under non-impulsive wave conditions, and the numerical calculation result of empirical formula was evaluated slightly smaller than the experimental result in R_c/H_mo < 0.8 and slightly larger than the experimental result in R_c/H_mo > 0.8. The results of this model were well represented in both the exponential curve and the power curve under impulsive wave conditions. Therefore, it was confirmed that this numerical model can simulate the wave overtopping rate caused by nonlinear irregular waves in an vertical wall structure.

• International Journal of Highway Engineering
• /
• v.8 no.4 s.30
• /
• pp.159-179
• /
• 2006

By using the current road design method that is based on the regulation about structure and facilities standard of the road and the route plan guide of a national road and the alignment optimization road design method which is studied in the inside and outside of country, this study operate the route plan of the sample study and compare and analysis the route character, consequently the current design method has local optimization that is formed the plan by the stage and the section. Alignment optimization road design has the system optimal route search. But cost function has limite that caused by construction parameter that is not included in cost function. So we design a road route included cost function in main fields. As a result, we obtain a realistic and economically road route. The alignment optimization road design model has to be made up some problems, like the change of vertical gradient in the tunnel section, though this defects it has a lot of merits as a geometric design tool, especially in the feasibility study and the scheme design.

• Journal of Korean Society of Transportation
• /
• v.24 no.5 s.91
• /
• pp.109-121
• /
• 2006

The road should be designed in the consistent alignment which the driver can drive safely. Also, proper highway environments in order to maintain optimal operational speeds on highway sections should be provided In design stage, for highway environments, it is essential for an operational speed estimation model to different highway environments. If a method which could evaluate the status of the road safety is developed through this operational speed estimation model, it is possible to provide safe and more comfortable highways to road users. In the study factors to effect on operational speeds are classified into three groups horizontal & vertical alignments and traffic operation characteristic factors. Factors are chosen to effect on operational speeds by using collation analysis as classifications of tangent sections, horizontal curve sections and vertical curve sections. In order to develop operational speed estimation models in express highways, multi-regression analysis has been used in this study using the selected factors. This study has meaning that the developed estimation models for operational speeds and evaluation of degree of safety to horizontal and vortical alignments simultaneous. In order to represent whole area of the country with the developed models, the models should be re-analyzed with vast data related with road alignment factors in the near future.

• Journal of the Korean Institute of Gas
• /
• v.2 no.1
• /
• pp.23-27
• /
• 1998

To protect the underground pipeline from the mechanical damage and to enhance the cathodic protection effect, the river sand has been backfilled traditionally around the buried pipeline. However, river sand became depleted and expensive. One has to seek for the economic alternative materials. Crashed stone is a good candidate for the backfill material. In this study, how much the particle size and shape of the crashed stone can effect on the gas pipeline coating was examined. A series of laboratory and field test was performed. In the Lab, the increasing loads were applied to the coated pipeline surrounded by the crashed stone, where no significant damage was observed.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.3 s.345
• /
• pp.126-134
• /
• 2006

Traditional TCP implementations have the under-utilization problem in large bandwidth delay product networks especially during the startup phase. In this paper, we propose a delay-based congestion control(DCC) mechanism to solve the problem. DCC is subdivided into linear and exponential growth phases. When there is no queueing delay, the congestion window grows exponentially during the congestion avoidance period. Otherwise, it maintains linear increase of congestion window similar to the legacy TCP congestion avoidance algorithm. The exponential increase phase such as the slow-start period in the legacy TCP can cause serious performance degradation by packet losses in case the buffer size is insufficient for the bandwidth-delay product, even though there is sufficient bandwidth. Thus, the DCC uses the RTT(Round Trip Time) status and the estimated queue size to prevent packet losses due to excessive transmission during the exponential growth phase. The simulation results show that the DCC algorithm significantly improves the TCP startup time and the throughput performance of TCP in large bandwidth delay product networks.

• Journal of Korean Society of Transportation
• /
• v.25 no.1 s.94
• /
• pp.23-35
• /
• 2007

Freeway diverging areas are very vulnerable to traffic accidents due to abrupt vehicle speed changes and geometric changes. Therefore, in designing diverging areas, much attention should be Paid to safety The Present design criteria about freeway diverging areas regulate transition sections for lane changes, deceleration lanes, transition corves for direction changes. and other similar items. However, the design criteria were often violated in implementation because of ambiguities in the criteria. This study aims at clarifying and improving the present design criteria for freeway diverging areas. For this, field survey data and traffic accident data for diverging areas were analyzed.

• Journal of the Korean Institute of Gas
• /
• v.2 no.1
• /
• pp.40-46
• /
• 1998

Mathematical modeling on the corrosion of the steel casing and main pipe due to the protection current resulting from a cathodic protection system was carried out using boundary element method. The model is consisted of Laplace's equation with non-linear boundary conditions(Tafel equations) and the iterative technique to determine the miexed potential of the steel casing. The model is applied to the normal steel casing section as well as abnormal one with defects such as metal touch and insulation defects. From the modeling procedure, we can calculate the potential distributions and current density distributions of the system. The theoretical results of the qualitatiive corrosion aspect along the steel casing and main pipe agree well with the experimental results within the experimental conditions studied.