• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.19-28
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• 2023

Timber structures are susceptible to moisture, contamination, and pest infestation, which can compromise their integrity and pose a significant fire hazard. Despite these drawbacks, timber's lightweight properties, eco-friendliness, and alignment with current architectural trends emphasizing sustainability make it an attractive option for construction. Moreover, timber structures offer economic benefits and provide a natural aesthetic that regulates building temperature and humidity. In recent years, timber domes have gained popularity due to their high recyclability, lightness, and improved fire resistance. Researchers are exploring hybrid timber and steel domes to enhance stability and rigidity. However, shallow dome structures still face challenges related to structural instability. This study investigates stability problems associated with timber domes, the behavior of timber and steel hybrid domes, and the impact of timber member positioning on dome stability and critical load levels. The paper analyzes unstable buckling in single-layer lattice domes using an incremental analysis method. The critical buckling load of the domes is examined based on the arrangement of timber members in the inclined and horizontal directions. The analysis shows that nodal snapping is observed in the case of a concentrated load, whereas snap-back is also observed in the case of a uniform load. Furthermore, the use of inclined timber and horizontal steel members in the lattice dome design provides adequate stability.

• Progress in Superconductivity and Cryogenics
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• v.12 no.4
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• pp.24-30
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• 2010

The renewable energy source is considered as a good measure to cope with the global warming problem and the fossil energy exhaustion. The construction of electric power plant such as an offshore wind farm is rapidly increasing and this trend is expected to be continued during this century. The bulky and long distance power transmission media is essential to support and promote the sustainable expansion of renewable energy source. DC power cable is generally considered as the best solution and the demand for DC electric power has been rapidly increasing. Especially, the high temperature superconducting (HTS) DC cable system begins to make a mark because of its advantages of huge power transmission capacity, low transmission loss and other environmental friendly aspects. Technical contents of DC HTS cable system are very similar to those of AC HTS cable system. However the DC HTS cable can be operated near its critical current if the heat generation is insignificant, while the operating current of AC HTS cable is generally selected at about 50~70% of the critical current because of AC loss. We chose the specifications of the cable core of 'Tres Amigas' project as an example for our study and investigated the heat generation when the DC HTS cable operated near the critical current by some electric and thermal analyses. In this paper, we listed some technical issues on the design of the DC HTS cable core and described the process of the cable core design. And the results of examination on the current capacity, heat generation, harmonic loss and current distribution properties of the DC HTS cable are introduced.

• Journal of Korea Trade
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• v.26 no.3
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• pp.23-44
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• 2022

Purpose - Recent issues such as vessel enlargement, strengthening of environmental regulations, and port smartization are expected to increase costs and intensify competition in the port industry. In the new normal era, when external growth has reached its limit, the efficient operation of ports is becoming indispensable for achieving sustainable growth. This study aims to identify the determinants of inefficiency by examining the cost structure and efficiency of container terminals in Korea and furthermore propose the political implications to derive the maximization of efficiency. Design/methodology - This study estimates the cost function of container terminal operators and identifies the efficiency of container terminals using stochastic cost frontier (SCF) in the first stage. In the second step, the SCF results are compared with the data envelopment analysis (DEA). Last, this paper proposes efficiency determinants on container terminal operation to establish appropriate strategies. Out of the 29 container terminal operators in South Korea, 13 operators participated in the survey. The translog cost function was estimated utilizing a total of 116 observations collected over the 2007-2017 period. Findings - Empirical analysis shows that economies of scale exist in Korea's container ports, which provides a rationale for the government's policy to establish the global terminal operator by integrating small terminal operators to enhance competitiveness. In addition, as a result of the determinants analysis, container throughput, weight of direct employment costs, and labour cost share have positive effects on improving cost efficiency, while inefficiency increases as the length of quay increases. More specifically, cost efficiency improves as the proportion of direct employment costs to outsourcing service costs increases. Originality/value - This study contributes to analyzing the inefficiency factors of container terminals through efficiency analysis with respect to a cost function. In addition, this study proposes the practical and political implications, such as establishing a long-term manpower pool, the application of the hybrid liner terminal system, and the construction of a statistical data system, to improve the cost inefficiency of terminal operators.

• Korea Trade Review
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• v.41 no.5
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• pp.163-185
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• 2016

The impact of global trade on developing countries is a critical subject. Especially in this country, under difficult conditions like political issues with North Korea, achieved a trade surplus of 90.2 billion dollars last year. While the service trade recorded a deficit of 15.7 billion dollars in the same period. According to WTO, services are either the result of a production activity that changes the conditions of the consuming units (transformation services), or facilitates the exchange of products or financial assets (margin services). To unify and compare with the trade and service statistics of countries, they assorted 12 classifications of services like Manufacturing service on physical inputs owned by others, Maintenance and repair service n.i.e., Transport, Travel, Construction, Insurance and pension service, Financial service, Charges for the use of intellectual property n.i.e., Telecommunications, Computer and information services, Other business services, Personal, cultural and recreational services, and Government goods and services n.i.e. Thus, this study is to estimate the international competitiveness of service trade between 2006 and 2015 in Republic of Korea, according to EBOPS 6th. As a result, total service volume of export and import has increased in the last 10 years. Its volume, recently, accounts for 22% of total goods trade. Also the Korean Government can make a supporting policy and decide a supporting business in terms of service trade. Finally, we can find a mutual connectivity within 12 service businesses and between Service and Goods.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.125-125
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• 2020

European Space Agency's Sentinel-1 has an improved spatial and temporal resolution, as compared to previous satellite data such as Envisat Advanced SAR (ASAR) or Advanced Scatterometer (ASCAT). Thus, the assumption used for low-resolution retrieval algorithms used by ENVISAT ASAR or ASCAT is not applicable to Sentinel-1, because a higher degree of land surface heterogeneity should be considered for retrieval. The assumption of homogeneity over land surface is not valid any more. In this study, considering that soil roughness is one of the key parameters sensitive to soil moisture retrievals, various approaches are discussed. First, soil roughness is spatially inverted from Sentinel-1 backscattering over Yanco sites in Australia. Based upon this, Artificial Neural Networks data (feedforward multiplayer perception, MLP, Levenberg-Marquadt algorithm) are compared with Fractal approach (brownian fractal, Hurst exponent of 0.5). When using ANNs, training data are achieved from theoretical forward scattering models, Integral Equation Model (IEM). and Sentinel-1 measurements. The network is trained by 20 neurons and one hidden layer, and one input layer. On the other hand, fractal surface roughness is generated by fitting 1D power spectrum model with roughness spectra. Fractal roughness profile is produced by a stochastic process describing probability between two points, and Hurst exponent, as well as rms heights (a standard deviation of surface height). Main interest of this study is to estimate a spatial variability of roughness without the need of local measurements. This non-local approach is significant, because we operationally have to be independent from local stations, due to its few spatial coverage at the global level. More fundamentally, SAR roughness is much different from local measurements, Remote sensing data are influenced by incidence angle, large scale topography, or a mixing regime of sensors, although probe deployed in the field indicate point data. Finally, demerit and merit of these approaches will be discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.121-128
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• 2009

The King George Island, where the King Sejong Station is located, represents one of the gateways to the Antarctica from the point of its geographical aspect. It also serves as an advanced post, and plays an important role in the extending for Korea's Antarctic research activities. The existence of maps is not only a basic element for the constructing geographic informations supporting these activities, but also an implied way of announcing the sovereignty over the KingSejong Station in global world. However, the precise surveying for the geographic information has not been carried out, and thus topographical maps as well as geographic information assuring enough accuracy are still missed in this area. This fact had forced Korea to rely on using maps produced by foreign countries. Therefore, this study aims to generate digital topographical maps of 1: 5,000 scale for the constructing geographic information using lightweight aerial photogrammetry system first. And further, it will contribute to offer practical base data for the future research related to the Antarctic environment through the analysis of glacier retreat and change using this new digital map comparing with existing one.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.80-81
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• 2020

Due to COVID 19, the global economy is facing a crisis situation, and in the export-oriented industry, companies must consider survival. The government and industry are striving to revitalize exports in a number of ways, and with restrictions on non-face-to-face export activities, they are contemplating various ways to implement non-face-to-face export marketing. Among them, various studies are being conducted in various industries on the part of conducting an online exhibition. In particular, the shipbuilding and offshore industry is a major export industry, and offline exhibitions held around the world were an important opportunity for marketing, and the use of online exhibitions to substitute for them is urgently needed. In this study, we study AR, VR, MR, etc., which are various element technologies necessary for building an online exhibition hall suitable for the shipbuilding and marine industry, and how they are applied to online exhibitions.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.167-168
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• 2020

In line with the low growth trend of the global economy, shipping companies and port companies are experiencing various management difficulties. However, at this time when the growth trend is stagnating, attempts to solve the breakthrough in growth with the technology of the 4th industrial revolution are occurring in various industries and technologies. In this study, in order to facilitate the construction of smart ports in the future, we will look at the current port system in Korea, and in the sense of the need for a basic study to diagnose the direction for more smooth policy introduction and technology introduction, Related exploratory studies were conducted. To achieve the purpose of this study, various previous studies were reviewed, news articles related to ports, reports of the Ministry of Oceans and Fisheries, and foreign literature were reviewed in a variety of ways, and based on this, we intend to present smart port introduction tasks and improvement plans.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.325-333
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• 2006

Recently, in the case of observing the global environment, satellite remote sensing technology has been important. It's because satellite remote sensing is valuable for assessing relatively large areas. But now, small scale remote sensing techniques are needed which can be applicable to the detail investigation of plant tree areas which afforest land after the large scale construction of roads, dams and airports. In this study, we tried to develop and propose a lower altitude sensing technique which can be used in ground remote sensing by using a CCD camera. As a result of this investigation the following can be concluded: We recognized the transference characteristics of filters which were used in comparative tests about the four ground remote sensing devices. We also found that the near-IR camera could be used for an imaging spectral radiometer in the extraction of the vegetation index. Furthermore, we found that the vegetation index has varied hour by hour during the day of the experiment. Finally, we brought about an increase phase of the NDVI in a forest fire, which caused considerable damage, by developing new ground remote sensing technology.

• Journal of English Language & Literature
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• v.56 no.2
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• pp.357-382
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• 2010

Motherhood as an ideological construction has been regarded as an oppressing apparatus enforced by patriarchism. On the one hand, demystifying motherhood helps expose dehumanization of women, and accordingly liberate women from being an ideal mother. On the other hand, however, feminists' attempts to unearth the distorted images of mothers result in devaluation of such values as love and sacrifice attached to motherhood. "Tell Me a Riddle" by Tillie Olsen, who is a declared socialist as well as a feminist, occupies a significant position in a sense that it neither condemns motherhood as evil nor idealizes it. Through the main character, Eva, it examines the meaning of motherhood in a way that a real mother experiences it in a real life, and thus Olsen challenges the readers to ponder upon the mothers' dilemma: a conflict between a desire for self-fulfillment and sacrifice for others. Eva, a mother of seven grown-up children, and now dying, shows an ambivalent attitude toward motherhood. She realizes that she is a victim of idealized motherhood in that, toward the end of her life, she feels uncomfortable accepting her personal desires as they are. Yet at the same time, she appreciates her experiences as a mother in that she could consume her passion for the ideals as she has spent her youth working toward, trying to construct an idealistic socialist country. Eva's real ideal, as a human being, is to live "with" others, not just "for" others. In other words, she does not want to allow herself to live only for others in the name of the mother because she does not have any alternatives to do otherwise. Rather, she desires to live a life of voluntary sacrifice and love. In this way, through Eva, Olsen tries to help us to construct a community where we--not just mothers-can live "with" others.