• Journal of Korea Water Resources Association
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• v.56 no.9
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• pp.543-551
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• 2023

Snow is an essential climate factor that affects the climate system and surface energy balance, and it also has a crucial role in water balance by providing solid water stored during the winter for spring runoff and groundwater recharge. In this study, statistical analysis of Local Data Assimilation and Prediction System (LDAPS), Modern.-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), and ERA5-Land snow depth data were used to evaluate the applicability in South Korea. The statistical analysis between the Automated Synoptic Observing System (ASOS) ground observation data provided by the Korea Meteorological Administration (KMA) and the reanalysis data showed that LDAPS and ERA5-Land were highly correlated with a correlation coefficient of more than 0.69, but LDAPS showed a large error with an RMSE of 0.79 m. In the case of MERRA-2, the correlation coefficient was lower at 0.17 because the constant value was estimated continuously for some periods, which did not adequately simulate the increase and decrease trend between data. The statistical analysis of LDAPS and ASOS showed high and low performance in the nearby Gangwon Province, where the average snowfall is relatively high, and in the southern region, where the average snowfall is low, respectively. Finally, the error variance between the four independent snow depth data used in this study was calculated through triple collocation (TC), and a merged snow depth data was produced through weighting factors. The reanalyzed data showed the highest error variance in the order of LDAPS, MERRA-2, and ERA5-Land, and LDAPS was given a lower weighting factor due to its higher error variance. In addition, the spatial distribution of ERA5-Land snow depth data showed less variability, so the TC-merged snow depth data showed a similar spatial distribution to MERRA-2, which has a low spatial resolution. Considering the correlation, error, and uncertainty of the data, the ERA5-Land data is suitable for snow-related analysis in South Korea. In addition, it is expected that LDAPS data, which is highly correlated with other data but tends to be overestimated, can be actively utilized for high-resolution representation of regional and climatic diversity if appropriate corrections are performed.

• Korean Journal of Construction Engineering and Management
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• v.15 no.5
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• pp.61-70
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• 2014

Various procurement systems for Architecture-Engineering service for public construction project are currently established by construction-related law. However, comprehensive framework and criteria for the selection of Architecture-Engineering firm are in absence. Even though various selection methods for Architecture-Engineering service are currently established by law, cost-based selection method is mainly used in selecting Architecture-Engineering firm for the service. This paper examined current use of procurement system for Architecture-Engineering service and drew problems in practice. Through analysis of problems and bench-marking of those systems in advanced countries and international organizations, several strategies to improve performance of Architecture-Engineering service and to maximize the efficiency were suggested. The suggestions include framework and guideline to select a procurement method for the service which is being considered for the project and way of improving current procurement system. These suggestions will be a foundation for utilizing appropriate procurement system for the specific project and can make domestic Architecture-Engineering firm more competitive in the global market by breaking form the cost-based selection method in the selection of Architecture-Engineering firms.

• The Journal of Small Business Innovation
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• v.19 no.2
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• pp.37-52
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• 2016

Making efforts to break down the barriers between the intra-company departments as well as cooperating with external partners can become the driving force to create a successful innovation in the new product development (NPD) process. This study deals with how the key factors of collaborative innovation success are working in the process of NPD collaboration. Using case analysis of the NPD process, where a large retailer and small and medium-sized suppliers cooperate, we found that the small and medium-sized suppliers achieved greater 'short-term' performances in the collaboration than the large firm, although the long-term performance is not clear. Among the six antecedents of innovation success, relationship-specific investment played a critical role in motivating the supplier's participation in the NPD process. Adopting a 'closed' network in which the two suppliers interact directly with each other and create new knowledge for the NPD process played an important role in producing a quality product in a reduced development time. Unlike previous studies about the retailer-supplier cooperation for NPD in the food industry suggesting that position differences cause communication problems which is a major obstacle to the NPD success. This study suggests that large retailer's initiative role is a critical success factor in the NPD by the cooperation between small and medium-sized suppliers and large retailers.

• Membrane Journal
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• v.28 no.2
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• pp.113-120
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• 2018

Global warming due to indiscriminate carbon dioxide emissions has a profound impact on human life by causing abnormal climate change and ecosystem destruction. As a way to reduce carbon dioxide emissions, in this study, we presented a polymeric membrane prepared by blending a self-crosslinkable P(GMA-g-PPG)-co-POEM (SP) copolymer and commercial polymer polyvinylpyrrolidone (PVP). As the content of PVP increased, it was observed that the gas permeance decreased and $CO_2/N_2$ selectivity increased. At 30 wt% PVP content, the $CO_2$ permeance of the membrane decreased from 72.9 GPU of pure SP polymer to 12.6 GPU, while $CO_2/N_2$ selectivity improved by 79% from 28.1 to 50.4. It results from the hydrogen bonding between the SP copolymer and PVP, leading to more compact structure of the polymer chains, which was confirmed by FT-IR, TGA, XRD and SEM analysis. Therefore, we suggest that the permeance and selectivity of the membranes can be easily adjusted as desired by controlling the PVP content in the SP/PVP polymer blend.

• International Commerce and Information Review
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• v.18 no.3
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• pp.205-226
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• 2016

As knowledge workers have increased and information interchanges become more diverse, only the resources of internal enterprise is not longer useful, and the practical use of external information through information public sharing network is even more crucial. But, few studies that use both internal and external information sharing systems together have been conducted. In this research, we carried on the depth interview to analyze the main factors that intend to utilize outside information as well as to share inside information voluntarily. In conclusion, sharing internal information is directly involved with the performance of their job exchanging simple data, past documents, and technical materials. On the other hand, using the external information belonged to several other organizations is mostly caused by the voluntary participants' satisfaction sharing their individual experience through the network systems. Based on the study, we propose the idea that can activate both internal and external information sharing network through the system with user feedback function regarding the customized information, and with the space expansion where people can freely raise their private opinion. We also introduce the plan of the construction of communication systems with various experts, and the development of compatible devices with diverse interfaces.

• Korean Journal of Construction Engineering and Management
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• v.17 no.2
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• pp.3-11
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• 2016

CM at Risk has been introduced in Korea to keep up with the global standards of construction management and provide a higher quality of cm service in line with a rapid change of the construction industry recently. However, it is widely considered that more time would required to settle down the system due to a lack of understanding towards CM at Risk, shortage of reliability and low capability to manage and undertake CM at Risk. Therefore, this research is analyzed problems of contract types, open book policies, and contract conditions of 33 numbers of projects undertaken by a bespoke domestic construction management firm in this research. Moreover, this research is suggested a method to establish an open book policy of CM at Risk aiming a better customers satisfaction through staff training, simplifying and improving a payment system, and a way to settle down an open book policy by improving a performance management system on site. It's expected that this research will contribute to a more competitive system with more dominating the market and a differentiation of the service so as clients to rely more on the CM at Risk.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.4
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• pp.437-444
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• 2020

A lunar rover's optical camera is used to provide navigation and terrain information in an exploration zone. However, due to the scant presence of atmosphere, the Moon has homogeneous terrain with dark soil. Also, in extreme environments, the rover has limited data storage with low computation capability. Thus, for successful exploration, it is required to examine feature detection and matching methods which are robust to lunar terrain and environmental characteristics. In this research, SIFT, SURF, BRISK, ORB, and AKAZE are comparatively analyzed with lunar terrain images from a lunar rover. Experimental results show that SIFT and AKAZE are most robust for lunar terrain characteristics. AKAZE detects less quantity of feature points than SIFT, but feature points are detected and matched with high precision and the least computational cost. AKAZE is adequate for fast and accurate navigation information. Although SIFT has the highest computational cost, the largest quantity of feature points are stably detected and matched. The rover periodically sends terrain images to Earth. Thus, SIFT is suitable for global 3D terrain map construction in that a large amount of terrain images can be processed on Earth. Study results are expected to provide a guideline to utilize feature detection and matching methods for future lunar exploration rovers.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.310-317
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• 2017

Recently, many nations are operating and developing Global Navigation Satellite System (GNSS). Also, Satellite Based Augmentation System (SBAS), which uses the geostationary orbit, is operated presently in order to improve the performance of GNSS. The most widely-used SBAS is Wide Area Augmentation System (WAAS) of GPS developed by the United States. SBAS uses various algorithms to offer guaranteed accuracy, availability, continuity and integrity to its users. There is algorithm for guarantees the integrity of the satellite. This algorithm calculates the satellite errors, generates the correction and provides it to the users. The satellite orbit errors are calculated in three-dimensional space in this step. The reference placement is crucial for this three-dimensional calculation of satellite orbit errors. The wider the reference placement becomes, the wider LOS vectors spread, so the more the accuracy improves. For the next step, the regional features of the US and Korea need to be analyzed. Korea has a very narrow geographic features compared to the US. Hence, there may be a problem if the three-dimensional space method of satellite orbit error calculation is used without any modification. This paper suggests a method which uses scalar values to calculate satellite orbit errors instead of using three-dimensional space. Also, this paper proposes the feasibility for this method for a narrow area. The suggested method uses the scalar value, which is a projection of orbit errors on the LOS vector between a reference and a satellite. This method confirms the change in errors according to the baseline distance between Korea and America. The difference in the error change is compared to present the feasibility of the proposed method.

• Atmosphere
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• v.28 no.1
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• pp.37-51
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• 2018

In this study, we investigate the performance of Global Seasonal Forecasting System version 5 (GloSea5) in Korea Meteorological Administration on the relationship between El $Ni{\tilde{n}}o$ and East Asian climate for the period of 1991~2010. It is found that the GloSea5 has a great prediction skill of El $Ni{\tilde{n}}o$ whose anomaly correlation coefficients of $Ni{\tilde{n}}o$ indices are over 0.96 during winter. The eastern Pacific (EP) El $Ni{\tilde{n}}o$ and the central Pacific (CP) El $Ni{\tilde{n}}o$ are considered and we analyze for EP El $Ni{\tilde{n}}o$, which is well simulated in GloSea5. The analysis period is divided into the developing phase of El $Ni{\tilde{n}}o$ summer (JJA(0)), mature phase of El $Ni{\tilde{n}}o$ winter (D(0)JF(1)), and decaying phase of El $Ni{\tilde{n}}o$ summer (JJA(1)). The GloSea5 simulates the relationship between precipitation and temperature in East Asia and the prediction skill for the East Asian precipitation and temperature varies depending on the El $Ni{\tilde{n}}o$ phase. While the precipitation and temperature are simulated well over the equatorial western Pacific region, there are biases in mid-latitude region during the JJA(0) and JJA(1). Because the low level pressure, wind, and vertical stream function are simulated weakly toward mid-latitude region, though they are similar with observation in low-latitude region. During the D(0)JF(1), the precipitation and temperature patterns analogize with observation in most regions, but there is temperature bias in inland over East Asia. The reason is that the GloSea5 poorly predicts the weakening of Siberian high, even though the shift of Aleutian low is predicted. Overall, the predictability of precipitation and temperature related to El $Ni{\tilde{n}}o$ in the GloSea5 is considered to be better in D(0)JF(1) than JJA(0) and JJA(1) and better in ocean than in inland region.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.217-230
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• 2020

Global warming has increased interest in reducing greenhouse gas emissions. And a policy has effort to reduce energy consumption as a greenhouse gas reduction plan. In Korea, 25% of total energy is consumed in the building sector. In order to reduce energy consumption of buildings, it is possible to expand the utilization of wood as a structural material or thermal insulation materials with low thermal conductivity. It is also reported that when used as an interior finishing material, the energy consumption of the building is reduced by up to 7% by insulation performance. In this study, the heat transfer characteristics and the heat capacity were compared according to the three type of finishing materials(cement, paulownia coreana, medium density fiberboard) normally used as indoor finish materials. Through this study, most of the heat transfer volumes are transferred in the form of radiant heat, and the result was derived from the highest amount of energy and heat transfer in the use of paulownia coreana. When indoor finishing materials are used as wood, it is deemed that energy efficiency inside the building will be improved.