• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.308-308
• /
• 2021

다목적댐의 홍수조절운영에 있어서 댐유입량은 직접 관측의 어려움과 오차로 인해 정확한 유량을 산정하는데 한계가 있다. 남강댐 유역의 경우 유역면적대비 과소한 저수용량으로 말미암아 급격한 홍수유입이 발생할 경우 유출률이 비정상적 수치를 보이는 경우가 종종 발생하고 있다. 본 연구에서는 물리기반의 격자형 유출모형을 댐 직상류 잔유역에 적용하여 유출률을 산정 후 남강댐 계측유입량의 타당성을 간접적으로 검증할 수 있는 방법론을 제시하고자 한다. 댐유역에서 잔유역은 직상류 수위표지점 하류의 유역을 일컬으며, 이들 수위표지점에서 홍수시의 배수영향은 최소화될 만큼 이격되어 있고, 댐체 혹은 취수탑에 부착된 수위표와는 달리 기계적 진동의 영향이 최소화되어 있다고 가정한다면, 수위계측지점의 유량을 경계조건으로 활용하여 작은 면적에 대한 정밀한 수문학적 유출모델링을 통하여 비교적 신뢰성있는 유출값을 추정할 수 있다는 장점이 있다. 남강댐 잔유역은 유역 내 산청, 신안, 창촌 수위관측소를 기준으로 상류의 유역을 제외한 부분으로 설정하였다. 본 연구에서는 210m 격자에 대하여 모든 입력자료를 가공하였으며, 입력자료 중 지형자료는 WAMIS에서 제공한 DEM, 토지피복도, 토양도를 활용하였다. 강우자료는 유역 내 위치한 25개 강우관측소의 시단위 강우자료를 활용하였고, 강우사상은 진주 기상관측소의 일우량 100mm 이상을 기준으로 총 8개의 강우사상을 선정하였다. 남강댐 유역의 유출률을 산정하기 위해 산청, 창촌, 신안 등 3개의 수위관측소의 관측유량을 경계조건으로 사용하였고, 모의된 수문곡선의 총유량과 첨두유량을 관측값과 비교하였다. 유출률을 산정하기 위한 기준시간은 강우시작부터 강우종료 후 48시간으로 설정하였다. 유출률은 강우사상별로 편차가 심한 특성을 보이고 있었으며, 전체적으로는 계측유량기준 106~39.1%의 유출률이 보정된 유량을 통해서는 85~33%의 유출률로서 계측유량이 전반적으로 과대추정 되는 경향이 있었음을 확인할 수 있었다. 이들 중 2010년 7월 강우사상은 관측 유입량 기준 95.6%의 유출률을 보여, 추정유량 58.5%대비 상당한 과대추정 경향을 보인 사례로 판단할 수 있었다. 수문학적 유입량 추정방법은 현장계측을 대체할 수 있는 기법으로는 무리가 있으나 현장계측의 신뢰도를 평가하기 위한 목적으로는 유용한 대안이 될 수 있을 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.2D
• /
• pp.127-134
• /
• 2010

Tunnel sections on the highway are different from rest of sections on the highway in terms of velocity, the number of passing cars, and vehicle density which, in particular, affect drivers' behavior before and after drivers pass through the tunnel. However, literature review reveals that former studies are too focused on quantitative indicator to consider qualitative aspects. Therefore, this paper conducts survey questionnaire and IPA (Importance Performance Analysis) to find out qualitative improvements on velocity drop on the tunnel sections. The results show as follows: First, drivers require improvements of tunnel form (length and curved form inside tunnel) which is derived from long distance tunnel. Second, experts primarily ask for amendment of geometric characteristics. With comparison of requirements of both drivers and experts, there are many differences in length of tunnel and form of curved tunnel. This also presents that drivers don't satisfy with both length of tunnel and form of curved tunnel that are provided as a part of highway design factors.

• The Journal of Bigdata
• /
• v.6 no.2
• /
• pp.17-28
• /
• 2021

Current development of technologies related to 4^th industrial revolution and the pandemic of COVID-19 lead the rapid expansion of e-marketplace. The level of competition among several companies gets increased by introducing different strategies. To cope with the current change in the market and satisfy the customers who request the better delivery service, the new concept, fulfillment, has been introduced. It makes the leadtime of process from order picking to delivery reduced and the efficiency improved. Still, the efficiency of operation in fulfillment centers constrains the service level of the entire delivery process. In order to solve this problem, several different approaches for demand forecasting and coordinating supplies using Bigdata, IoT and AI, which there exists the trivial limitations. Because it requires the most lead time for operation and leads the inefficiency the process from picking to packing the ordered items, the logistics service providers should try to automate this procedure. In this research, it has been proposed to develop the efficient plans to automate the process to move the ordered items from the location where it stores to stage for packing using AGV and AMR. The efficiency of automated devices depends on the number of items and total number of devices based on the demand. Therefore, the result of simulation based on several different scenarios has been analyzed. From the result of simulation, it is possible to identify the several factors which should be concerned for introducing the automated devices in the fulfillment centers. Also, it can be referred to make the optimal decisions based on the efficiency metrics.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.1D
• /
• pp.1-10
• /
• 2008

Recently, the Seoul Metropolitan Government (SMG) has initiated several urban redevelopment projects to revitalize the downtown well equipped for transit oriented development (TOD). Since, TOD should incur higher density development in our context, it has negative impacts on travel patterns, congestion, and urban environmental quality. The purpose of this study is to develop new transportation service index which can facilitate higher density TOD. This study includes relevant foreign case studies, the development of multimodal transportation index, and the impact analysis of TOD when it is applied in the downtown Seoul. In chapter III, it developed a so-called ITLOS, new multimodal transportation service index which shows the possibility of accommodating further development by integrating roadway service index with public transportation service index. The study sets ten policy scenarios by varying densities, and run the Seoul Congestion Management Model (SECOMM) to estimate the sustainable transportation impacts of TOD in the downtown. Travel speed index that only represents the availability of road capacity for development reveal that higher density development in the downtown can deteriorate traffic congestion while improving region-wide transportation level of service in Seoul. Also, it is proved that higher density development is more feasible when using ITLOS as the index because it considers not only available road capacity but subway capacity in the analysis area.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.4D
• /
• pp.459-467
• /
• 2008

Because of the insufficiency of ground space, the utilization of underground is getting more and more in these days. Moreover, underground space is being used not only buildings but multipurpose space for movement, storage and shopping. However, ground space has vital weakness for fire compared to ground space. Especially in case of underground shopping center, there are various stuffs to burn and poisonous gas can be exposed on this count when the space is burned. A large number of casualties can be also occurred from conflagration as underground space has closed structures that prevent rapid evacuation and access. Therefore, this research proposes the guidance methodology for evacuation from conflagration in large-sized underground facilities. In addition, suggested methodology uses high technology wireless sensor information from up-to-date ubiquitous sensor networks. Fire information collected by sensors is integrated with existing underground facilities information and this is sent to guidance systems by inducing process. In the end, this information is used for minimum time paths finding algorithm considering the passageway capacity and distance. Also, usefulness and inadequacies of proposed methodology is verified by a case study.

• Membrane Journal
• /
• v.34 no.2
• /
• pp.132-139
• /
• 2024

The ion exchange resin used to remove total dissolved solids (TDS) is used by being packed in a column, and sufficient contact time between the ionic material and the ion exchange resin is required during the ion exchange process. In this study, the ion exchange resin that exhibits high TDS reduction even with a short contact time through pulverization of the ion exchange resin was characterized. The optimal size of resin considering flowability was over 100 ㎛. The highest pulverizing yield were obtained that 250~500 ㎛ size and 100~250 ㎛ size were 67.3% and 36.9%, respectively. Also, the highest yield and the pulverizing time of 100~500 ㎛ size was 87.1% and 2 minutes, respectively. Under batch test conditions, the time to reach a removal rate of 95% and 99% for 250~500 ㎛ resins was 1.82 and 1.96 times faster than non-pulverized ion exchange resin, respectively. The 100~250 ㎛ resins showed 15.9 times and 6.18 times faster, respectively. Under the column test, a total of 1.74 g of NaCl was removed by non-pulverized ion exchange resins, 1.83 g of NaCl was removed by 250~500 ㎛ resins and 1.63 g of NaCl was removed by 100 and 250 ㎛ resins. As the size of the resin decreased, the capacity slightly decreased. As a result, it was observed that the pulverized ion exchange resins could be a method of achieving high TDS removal performance under short contact time.

• Membrane Journal
• /
• v.34 no.2
• /
• pp.154-162
• /
• 2024

Anion exchange membranes (AEMs) are essential components in water electrolysis systems, serving to physically separate the generated hydrogen and oxygen gases while enabling the selective transport of hydroxide ions between electrodes. Key characteristics sought in AEMs include high ion conductivity and robust chemical and mechanical stability in alkaline. In this study, quaternized Poly(terphenyl piperidinium)/cellulose nanocrystals (qPTP/CNC) mixed matrix membrane was fabricated. The polymer matrix, PTP, was synthesized via super-acid polymerization, known for its excellent ion conductivity and alkaline durability. The qPTP/CNC membrane showed a dense and uniform morphology without significant voids or large aggregates at the polymer-nanoparticle interface. The qPTP/CNC membrane containing 2 wt% CNC demonstrated a high ion exchange capacity of 1.90 mmol/g, coupled with low water uptake (9.09%) and swelling ratio (5.56%). Additionally, the qPTP/CNC membrane showed significantly lower resistance and superior alkaline stability (384 hours at 50℃ in 1 M KOH) compared to the commercial FAA-3-50 membrane. These results highlight the potential of hydrophilic additive CNC in enhancing ion conductivity and alkaline durability of ion exchange membranes.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.7
• /
• pp.661-667
• /
• 2009

Trabecular-bone-mimicking phantoms consisting of parallel-nylon-wire arrays were used to investigate correlations of phase velocity and attenuation coefficient with structural properties in trabecular bone. Trabecular separation (Tb.Sp) of the 7 trabecular-bone-mimicking phantoms ranged from 300 to $900\;{\mu}m$ and volume fraction (VF) from 1.6% to 8.7%. Phase velocity and attenuation coefficient of the phantoms were measured by using a through-transmission method in water, with a matched pair of broadband unfocused transducers with a diameter of 12.7 mm and a center frequency of 1 MHz. Phase velocity and attenuation coefficient at 1 MHz decreased almost linearly with increasing Tb. Sp and increased almost linearly with increasing VF. The simple and multiple linear regression models with phase velocity and attenuation coefficient as independent vanables and Tb.Sp and VF as dependent variables demonstrated that the coefficients of determination for the prediction of VF were higher than those for the prediction of Tb.Sp. The results obtained in the trabecular-bone-mimicking phantoms consisting of parallel-nylon-wire arrays were consistent with those in human trabecular bone suggesting that the structural properties can be estimated from the measurements of phase velocity and attenuation coefficient in trabecular bone.

• Smart Media Journal
• /
• v.13 no.3
• /
• pp.18-26
• /
• 2024

Road surface monitoring is essential for maintaining road environment safety through managing risk factors like rutting and crack detection. Using autonomous driving-based UGVs with high-performance 2D laser sensors enables more precise measurements. However, the increased energy consumption of these sensors is limited by constrained battery capacity. In this paper, we propose a fusion sensor system for efficient surface monitoring with UGVs. The proposed system combines color information from cameras and depth information from line laser sensors to accurately detect surface displacement. Furthermore, a dynamic sampling algorithm is applied to control the scanning frequency of line laser sensors based on the detection status of monitoring targets using camera sensors, reducing unnecessary energy consumption. A power consumption model of the fusion sensor system analyzes its energy efficiency considering various crack distributions and sensor characteristics in different mission environments. Performance analysis demonstrates that setting the power consumption of the line laser sensor to twice that of the saving state when in the active state increases power consumption efficiency by 13.3% compared to fixed sampling under the condition of λ=10, µ=10.

• Journal of Korean Society of Disaster and Security
• /
• v.16 no.4
• /
• pp.75-84
• /
• 2023

Many developing countries face challenges in estimating long-term discharge due to the lack of hydrological data for water supply planning, making it difficult to establish a rational water supply plan for decision-making on water distribution. The study area, the Bandung region in Indonesia, is experiencing rapid urbanization and population concentration, leading to a severe shortage of freshwater. The absence of water reservoir prediction methods has resulted in a water supply rate of approximately 20%. In this study, we aimed to propose an approach for predicting water reservoirs in developing countries by analyzing water safety and potential water supply using the MODSIM (Modified SIMYLD) network model. To assess the suitability of the MODSIM model, we applied the unit hydrograph method to calculate long-term discharge based on 19 years of discharge data (2002-2020) from the Pataruman observation station. The analysis confirmed alignment with the existing monthly optimal operation curve. The analysis of power plant capacity revealed a difference of approximately 0.30% to 0.50%, and the water intake safety at the Pataruman point showed 1.64% for Q95% flow and 0.47% for Q355 flow higher. Operational efficiency, compared to the existing reservoir optimal operation curve, was measured at around 1%, confirming the potential of using the MODSIM network model for water supply evaluation and the need for water supply facilities.