• Architectural research
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• v.7 no.2
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• pp.91-96
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• 2005

The purpose of this study is to clarify the reality of labor and capital productivity in the construction industry through an industry-level approach and to analyze the relationship between labor and capital productivity using a Cobb-Douglas production function. According to the research results, the construction industry has shown a very high capital productivity, while labor productivity has kept up a low level during the 1980s and 1990s. The reason was because of the lack of skillful construction workers and the decrease of capital. Meanwhile, the construction productivity has greatly increased since 2000 when there was no change in wages. This was because of a large inflow of low-wage foreign workers while the amount of value added has dramatically increased due to the liberalized sale price of apartment buildings. According to the analysis by the Cobb-Douglas production function, the elasticity coefficient of V/L to K/L in the construction industry had decreased from 1.1663 in the $1^{st}$ period(1971-1988) to 0.4465 in the $2^{nd}$ period(1989-1997), and to 0.1664 in the $3^{rd}$ period(1998-2003). Such a result means that the allocation of labor has gradually increased while the allocation of capital has decreased. Moreover there was a big increase in allocation of labor after 1998 due to the excessive deterioration of capital. In conclusion, in order to raise the construction productivity and to avoid labor-intensive production methods, investment for capital should be more increased. In particular, new machinery and equipment that can actually substitute human labor in construction sites should be more developed and applied to construction sites.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.349-353
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• 2012

As the world wind energy market grows rapidly, the productions of wind power generation equipment have recently increased, but manufacturers are not able meet this requirement. Particularly offshore wind energy industry is one of the most popular renewable energy sectors. To generalize welding processes, the welding automation is considered for steel structure manufacturing in offshore wind energy to get high quality and productivity. Welding technology in construction of the wind towers is depended on progress productivity. In addition, the life of wind tower structures should be considered by taking account of the natural weathering and the load it endures. The root passes are typically deposited using Gas Tungsten Arc Welding(GTAW) with a specialized backing gas shield. Not only the validation consists of welders experienced in determining the welding productivity of the baseline welding procedure, but also the standard testing required by the ASME section IX and API1104 codes, toughness testing was performed on the completed field welds. This paper presents the welding characteristics of the root-pass welding of high tensile steel in manufacturing of offshore wind tower. Based on the result from welding experiments, optimal welding conditions were selected after analyzing correlation between welding parameters(peak current, background current and wire feed rate) and back-bead geometry such as back-bead width(mm) and back-bead height performing root-pass welding experiment under various conditions. Furthermore, a response surface approach has been applied to provide an algorithm to predict an optimal welding quality.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.201-207
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• 2018

Infrared(IR) heating has many advantages, such as energy efficiency, reduced heating time, cleanliness, equipment compactness, high drying rate and easy automation. These features of IR heating provide widely industrial applications, such as surface heat treatment in semiconductor fabrication, thermoforming of polymers, drying and disinfection of food products, heating to metal forging, and drying of wet materials. In this study, the characteristics of a protected gold mirror were examined by spectrophotometer and the lifetime of the coating layers were evaluated by a cross-cutting method and salt spray test. The effects of manufacturing conditions on the protected gold mirror were seen and remedies for these effects were noted in order to improve the properties of the protected gold mirror in the drying process. The reflectance and lifetime of the protected gold mirror was influenced by manufacturing conditions, such as surface roughness and forming conditions of the anti-oxide layer, the adhesion layer, the reflecting layer and the protection layer. The results of this study showed that the protected gold mirror manufactured using a buffing method for pre-treatment resulted in the most effective reflectance. In addition, $Al_2O_3$ coating on an Al substrate as an anti-oxide layer was more effective than the anodizing process in the test of reflectance. Furthermore, the protected gold mirror manufactured by layers forming of various materials resulted in the most effective reflectance and lifetime when coated with $Al_2O_3$ as the anti-oxide layer, coated Cr as the adhesion layer, and coated $MgF_2$ as the protection layer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.90-99
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• 2004

High speed info-communications equipment are required with development of highly information-oriented society, the intelligent industrial facilities and social systems such as administrative, financial and traffic systems, are gradually becoming to automation, which are composed of the integrated circuits and micro-semiconductors, remote control and operation. Thus modern micro-electronic circuits can frequently be damaged by lightning surge. The protection of electronic circuits from lightning overvoltages is concentrated very interesting. In this paper, for the purpose of providing the effective protection method of electronic devices such micro-computers from lightning surges in a residential building, the protection effect of surge protective devices according to types of system groundings were experimentally analyzed. Also the effective installation method of surge protective devices was examined and proposed. The installation of SPDs in retrofits was a high remnant voltage across the protected device owing to the inductance in the long wires to the SPDs. Finally the method of installing the SPD by twisted pain wires is remarkably effective for fast rising transient overvoltages.

• Journal of Navigation and Port Research
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• v.41 no.3
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• pp.149-154
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• 2017

Recently, container terminal operators have made efforts to develop an efficient remarshalling plan in response to the increase in automation of equipment handling and transport of containers in the terminals. Usually, containers are handled by multiple AYCs(automated yard cranes) in-yard in an automated container terminal, and terminal operators establish a remarshalling plan using slack time to increase the efficiency of ship operation. This study develops the optimal mathematical model through mixed integer programming as a solution to the problem of dispatching multiple AYCs. Considering the difficulty of direct application to the field due to computation time, we analyze the five prototypical dispatching rules for real world adaptation. A numerical experiment found that the maximum weight ratio (MR) rule and the maximum weight (MW) rule are the ideal dispatching solutions to the multiple AYCs dispatching problem.

• Structural Monitoring and Maintenance
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• v.2 no.1
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• pp.19-34
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• 2015

One of the main causes of a limited use of nondestructive evaluation (NDE) technologies in bridge deck assessment is the speed of data collection and analysis. The paper describes development and implementation of the RABIT (Robotics Assisted Bridge Inspection Tool) for data collection using multiple NDE technologies. The system is designed to characterize three most common deterioration types in concrete bridge decks: rebar corrosion, delamination, and concrete degradation. It implements four NDE technologies: electrical resistivity (ER), impact echo (IE), ground-penetrating radar (GPR), and ultrasonic surface waves (USW) method. The technologies are used in a complementary way to enhance the interpretation. In addition, the system utilizes advanced vision to complement traditional visual inspection. Finally, the RABIT collects data at a significantly higher speed than it is done using traditional NDE equipment. The robotic system is complemented by an advanced data interpretation. The associated platform for the enhanced interpretation of condition assessment in concrete bridge decks utilizes data integration, fusion, and deterioration and defect visualization. This paper concentrates on the validation and field implementation of two NDE technologies. The first one is IE used in the delamination detection and characterization, while the second one is the USW method used in the assessment of concrete quality. The validation of performance of the two methods was conducted on a 9 m long and 3.6 m wide fabricated bridge structure with numerous artificial defects embedded in the deck.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.351-354
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• 2011

Home network system makes it available for controlling inside home and for controlling from outside as well with personal computer, cellular phone or smart phone, by connecting diverse information equipments within home such as lighting, gas, and heating equipments with network Integrated server and wall-pad, which form home network system, have demerits as saying of being high-priced and of needing to implement network infrastructure. Also, there is also risk, which is unavailable for controlling equipments inside home, or can cause malfunction of equipments given the occurrence of a problem about integrated server This study suggested the intelligent home network system, which uses smart phone of supplementing these merits of home network system. It substituted high-specification input & output equipment in the currently and widely supplied smart phone for display and touch screen, which are user interface part of the existing wall-pad, and suggest the common home network system by concentrating management and control function of home network on smart phone.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.109-120
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• 2017

It is important to estimate objectively in the driving test. Especially, the driving test is examined by totally driving ability, rule observation and situational judgement. For this, a grading automation system for driving test was presented by using GPS, sensor data and equipment operation informations. This system is composed of vehicle mounted module, automatic grading terminal, data controller, data storage and processing server. The vehicle mounted module gathters sensor data in the car. The terminal performs automatic grading using the received sensor data according the driving test criterion. To overcome the misposition of vehicle in the map due to GPS error, we proposed the automatic grading system by map matching method, path deviation and return algorithm. In the experimental results, it was possible to grade automatically, display the right position of the car, and return to the right path under 10 seconds when the vehicle was out of the shadow region of the GPS. This system can be also applied to the driving education.

• Journal of the Korean housing association
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• v.18 no.1
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• pp.61-72
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• 2007

The purposes of this study were to summarize the concept of well-being and well-being apartment, to grasp the present condition of apartments which were introduced with well-being elements, and to find out the consumer preferences on well-being elements for apartment planning. Library and internet surveys were performed to summarize the concept of well-being and well-being apartment and to grasp the present condition of apartments which were introduced with well-being elements. Questionnaire survey was carried out from 2nd to 22nd of June 2005, to investigate the preferences on well-being elements for apartment planning. The respondents were 250 residents who are from thirties to fifties and living in urban area. As results, respondents think that 'living for health of body and mind' about concept of well-being and 'certificated apartments by green building rating system' or 'apartments introduced ecological factor' about concept of well-being apartment. They answered that 'yes' about 'Do you have intention to buy well-being apartment?'. The elements in aspect of complex planning having the preference were revealed that promenade for complex design, ecological garden or walking space for landscape design, outdoor exercise space for outdoor design, and security system for foundation equipment. The elements having the preference in aspect of public facilities were fitness room for sports & health facility and study room for cultural facility. The preferred elements in aspect of building and unit design were roof garden for building design, multi-functional room for unit floor plan, natural surface material for interior surface, ventilation system for indoor environment, control system for home automation, and food waste machine for home electronics.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.130-141
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• 2011

The intelligent excavating system(IES), the development in South Korea of which has been underway since 2006, aims for the full-scale automation of the excavation process that includes a series of tasks such as movement, excavation and loading. The core elements to ensure the quality and safety of the automated excavation equipment include 3D modeling of terrain that surrounds the excavating robot and the technology for detecting objects accurately(i.e., for detecting the location of nearby loading trucks and humans as well as of obstacles positioned on the movement paths). Therefore the purpose of this research is to ensure the quality and safety of automated excavation detecting the objects surrounding the excavating robot via a 3D laser scanning system. In this paper, an algorithm for estimating the location, height, width, and shape of objects in the 3D-realized terrain that surrounds the location of the excavator was proposed. The performance of the algorithm was verified via tests in an actual earthwork field.