Tai Sik Lee

Topological Competiveness Based on Social Relationships in the Korean Construction-Management Industry

AbstractA recent study reported that the construction management market has grown more competitive. In this environment, identifying a company’s competitive position enables a study of competitor strategies and the ability to select the most suitable path to profitability. This study suggests a methodology to analyze topological competiveness based on social relationships between firms modeled according to four subnetworks: Joint contract networks linked directly between firms, public and private networks linked indirectly by owners, and building and civil networks linked indirectly by work type. This study proposes an analytical framework measuring topological competiveness from four perspectives: The network topology among each subnetwork, centralities and structural positions among the firms, cohesive subgroups and strong relations in the subnetwork, and the structural equivalence among firms. Using 2,984 cases of Korean construction management projects from 1997 to 2013, an empirical analysis of topol...

Knowledge Asset Classification in the Construction Industry

Construction industries have given the efforts to develop the knowledge management (KM) to manage their knowledge assets, but it is still required to clarify the definition of knowledge assets to the same extent as has been done in the other industries. Major construction companies in Korea have built their own knowledge management system (KMS), but the systems are simply limited to classify the existing information. The classification of existing information is a small part of KM, and it is then desirable to tacit knowledge assets such as companys development strategy, culture and etc. This study suggested a new concept of KM for construction. With the widened concept, this study derived some knowledge asset elements based on a literature review and the interviews with KM specialists in construction companies. The suggested criteria on knowledge asset classification can be helpful in the evaluation of knowledge assets of own. In addition, it can be applicable in the derivation of the knowledge maps for the development of KMS considering the relationship between the separate information, and the development of education programs.

Agility and Traction for a Lunar Rough Terrain Exploration Rover

So far, exploration rovers on moon and mars limited there traverses to mostly flat and “easy” surfaces. On the other hand, there is Opportunity or the Mars Exploration Rover-B (MER-B) getting stuck in a 30 cm sand-dune on April 26, 2005. It took until June 4, 2005 for the rover to reach firm ground again. However, many important areas to be explored on mars and moon will require a rover to travel through uneven terrain covered with rocks, craters, and crevices. This paper presents the results of preliminary work in designing and testing a locomotion system offering high agility and wheels for the Extreme Rough Terrain Lunar Exploration Rover (ERTLER). The goal of the ERTLER is to position itself on top of lava tubes or steep crater walls, to install a drill-rig, to drill and extract a sample from inside a closed section of a tube. The locomotion concept is based on wheels mounted on six individually articulated legs. To add further agility, the head section can be separately articulated around three axis. Similar to a scraper, ERTLER is capable to make tight turns. Having each wheel individually powered and articulated will allow it to overcome steep slopes, cross crevices or inchworm itself out of difficult situations. The paper will present the tests of the first prototype in a mock lunar surfaces consisting of lunar soil simulant, craters, and rocks. A special section will focus on the design and testing of a rough-terrain wheel.

Automation System for Lunar Landing Pad

Concrete needs long time (28 day) for curing to reach enough strength in construction site. Also, it needs various materials. Thus, most of the construction sites in Extreme Environment select to deliver the prefabricated concrete modules. To construct structures on the Moon one has to select proper materials considering safety, cost, and procurement. Lunar concrete concept is quoted ISRU (In-Situ Resource Utilization). It only needs pressure and heat on lunar soil mixed with polymer. Moreover, the process of production is simple and short. This idea has born as terrestrial concrete request water, cement, and reinforces steel which has limit to manufacture in the Moon or to bring the massive resource from Earth because of the high cost. According to NASA and other space exploration roadmaps they are planning manned lunar exploration and building infrastructures in the Moon. This requires multiple landing of rockets that causes fine dust in the Moon which has harmful effect on human and infrastructures. Therefore, there is a need of lunar landing pad developed by ISRU. In addition as long term human existence and working on the lunar environment is dangerous automation system applied on rover needs to be developed. This paper introduces the lunar landing pad manufactured by the new type waterless concrete for lunar construction and presents automation system prototype for lunar launching pad construction.

Experimental Study of Lunar Regolith Anchoring Forces

Anchoring technology to secure building structures has already been in use over 6000 years ago. In the Bronze Age boats were anchored with a large rock at the end of a rope. Anchors will undoubtedly play an important role in enabling not only the exploration of the moon but also in the construction of lunar facilities. Unlike the earth, the lunar surface is amiss of convenient means to anchor one end of a cable or rod in rocks or tree trunks. Alternative earth anchors will face much different soil conditions to be successfully installed and used on the moon. The key problem is the fact that nothing is known about the behavior of anchors in lunar regolith. This paper presents the beginning of an experimental study to assess the effect of circular wedge anchoring in compacted lunar simulant. It will introduce to key hardware that has been built and explains the models behind the planned pull-out tests with various anchor lengths and anchor sizes. The goal of the upcoming work will be to establish a function between pull-out force and theoretical models of failure mechanisms. These functions should provide the basis for experimentally verifications in lunar environments. Results of the first pull-out tests will be presented during the Earth&Space 2010 conference.

Mobility Evaluation of an Anchored Lunar Exploration Rover

One of the recent issues for lunar exploration is finding a spot which has abundant amount of Moon ice and characterizing it. This is essential for future lunar outpost site selection. Orbital remote sensing is one way for prospecting Moon ice, this could provide variable information of global location. However, there is a limit of remote sensing as it cannot perform subsurface investigation and we cannot know which is actually over there before we touch it or feel it. Thus, developing a rover which could explore inside the crater is required for the Moon ice prospecting inside the Permanent Shadow Region (PSR). This paper presents the new approach to travel steep slopes through lunar anchoring supported rover tested on lunar similar environment. These are preliminary work in designing and testing a locomotion system offering high agility and tractions for the Extreme Rough Terrain Exploration Rover (ERTER). Results of the first locomotion tests will be presented during the Earth & Space 2012 conference.

Feasibility Study on Lunar Concrete Landing Pad

NASA has the plan for human exploration after the year 2020. This human exploration concept is based on ISRU (In Situ Resource Utilization). The concept of ISRU is reducing delivery cost supporting reasonable and efficient space exploration. And it plans to use the resources of the Moon and equipment at least. According to this human exploration plan, it mentioned how to make landing pad in the Moon such as soil compaction, dust and soft regolith replacement, and the bank construction around landing pad. But there is one problem with removing the dust that cannot be perfectly stabilized. Thus, this paper will present a new approach for landing pad construction in the Moon considering ISRU. First of all, this landing pad construction needs standardized building materials and methods suitable for lunar environment. Since Lunar Concrete using the lunar simulant called KOHLS-1(Korea-Hanyang Lunar Simulant- 1) has enough strength for compression, prototype is manufactured based on it. Then, landing pad is constructed in a similar way to lunar concrete manufacturing method. After making the landing pad, it is applied to feasibility study with SELENE-2 in JAXA, Astrobotic in Google X Prize and so on about compression strength. And the result has shown that it has enough strength which is suitable for other lading scenarios on the Moon.

Research on Productivity Improvement and Quality Control System Development for Automatic Line Stripe Removal System Using Dry Ice Blaster

Recently, the construction industry beyond the traditional construction has increased automatic construction system because it is necessary to development for skilled labor shortage, productivity improvement, cost saving, quality improvement, safety concerns. However, current line stripe removing process both labor intensive and time consuming, employing a conventional grinding type manual machine. Out of manual tasks trigger various dangers either traffic accidents or explosion of harmful gas used for finalizing removing process. Therefore, the part of automatic system is that Automatic line stripe removing is necessary to improvement in construction field. This study develops the new concept of system using previously developed dry ice blaster to improve the productivity of line stripe removal system and includes the system development to remove residuals generated after removal processes perfectly. Also, a quality control system, for work efficiency after removing line stripe, will be developed by adding post-work quality control processes to improve the work efficiency through quality check by operator after work.

The Improvement & Management of Historical Data at the Construction Site - Focused on the Supervision Committee

The importance of early project planning for construction projects is being widely recognized. If extensive historical data rehted to the project can be collected effectively from the planning phase, it can be a major resource for estimating cost and scope for the project. However, the reliability and use of data are quite low because they have usually utilized towards, administrative reports. Additionally, in construction work, experience on the field and know-how are prioritized over the ability to operate a computerized system; these factors have been barriers against the accumulation and management of the date system. In order to solve these problems, the procedural management of historical documents and team operations are necessary for collecting, storing, and utilizing the historical data. The Supervision Service is mostly related to paperwork from information transmission between the owner and contractor. This research will show a possible solution for the accumulation and management of historical data by understanding the present data management system through interviews and questionnaires at the field of construction.

Proposal for Applying Telematics Concept and Analyzing Economical Model in Site

Nowadays, the dependence of productivity on construction equipment is getting bigger and the mass of equipment cost is increase, those are indirect evidence of important of equipment. But construction field has the characteristic that is the various activities and wide work area. These make many problems in the operating of equipments. These problems bring about diminution of workability and productivity, in result it makes increase of cost and time. Owing to solve the problems, this study introduce of Telematics. This study analyzes process into its work and management for construction equipment using at the land work, and will apply Telematics to the field equipments.