• Journal of Navigation and Port Research
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• v.31 no.8
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• pp.629-635
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• 2007

Reduced crew performance is frequently cited as a major causal factor in maritime accident causation. Although considerable research has been conducted on the hours of work undertaken by seafarers through interviews and the analysis of records, experimental studies to observe the effects of factors such as high workload, shift patterns, stress, sleep deprivation and disturbance on the cognitive performance of mariners have been limited. Other safety-critical transport industries, such as aviation and rail, have developed fatigue management tools to help manage the work patterns of their operators. Such a tool for mariners would assist shipboard crew, marine pilots and shore management in planning and improving work schedules. The overall aim of this paper is to determine a fatigue factor, which can be applied to human performance data, as part of a software program that calculates total cognitive performance. This program enables us to establish the levels of cognitive performance of a group of marine pilots to test a decision-making task based on radar information. This paper addresses one of the factors that may contribute to the determination of various fatigue factors: the effect of different work patterns on the cognitive performance of a marine pilot.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.543-550
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• 2018

The rapid growth of IoT technology induced by the fourth industrial revolution has resulted in research into various types of wireless sensors, and applications based on this technology are prevalent in many areas. However, among the various sites where this technology is used, railway bridges and tunnels with lengths of tens of kilometers have problems with data acquisition, due to the signal noise induced by the long distance measurement and EMI induced by the high voltage power feeding system, when conventional electric sensors are used. To overcome these problems, many studies on fiber optic sensors have been conducted as a substitute for the conventional electric sensors. However, restrictions on the types of fiber optic sensors have limited their application in railways. For this reason, a hybrid measurement system with IoT based wireless data communication, in which both electric and fiber optic sensors can be applied simultaneously, has been developed. In this study, in order to evaluate the applicability of the hybrid measurement system developed in the previous study, a real-time test for 4 types of measurement environments, which reflect possible railway sites, is performed. As a result, it was confirmed that the signals from both the electric and fiber optic sensors, which were acquired at a remote area in real-time, showed good agreement with each other and that this measurement system has the potential to handle sensors with a sampling rate of 2.5 kHz. In the future, it is expected that the IoT-based hybrid measurement system will contribute to the improvement of structural safety by enabling real-time structural health monitoring when applied to various measurement sites.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.49-58
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• 2003

The Transport policies in Korea have been planned and implemented as a part of a larger economy policy based on the achievement of economic growth. As a result, previous transport policies have been focused mostly on the supply of transport infrastructure. The average annual economic growth of six percent and a twelve percent growth in motor vehicles until the late 90s led to the acceleration of the imbalance between the supply and demand of infrastructure. As such, there is a need to establish an innovative transportation policy in order to increase national competitiveness and provide momentum for national growth in the Twenty one century. This research has developed strategies and policies based on interviews that were carried out with specialists in transport field. Moreover, some transport policies have been established for the year 2020 through the conducting of a survey. The survey was conducted by interviewing respondents on making the priority of transport policies. which was then analyzed using the Data Envelopment Analysis with ranked voting data. The results are as follows. The most urgent matter was considered to be the development of a inter-modal transport system, followed by an integrated service system for public transport, and the need to increase the competitiveness of the transport and logistics industries and to further transport safety. Meanwhile, the provision of transportation for disabled people as well as the elderly was considered to be less important in Korea than in welfare nations. This stems from the belief as further attention needs to be paid to the construction of a public transport system, the establishment of transportation networks construction in preparation for reunification and the North-East Asian era, as well as the privatization of the transport infrastructure.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.21-28
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• 2009

A grouting method has been widely used in construction of large-scale structure to reduce permeability and reinforce the ground. If cement and grout material were not mixed well in the injection tip equipment, an opposite flow and interception state of the chemical grouting can occur. McG (Multi-mixing counterflow prevented Grouting, McG) method installed a special grouting device to allow better mixing of the grouting material(above fineness $6,000cm^2/g$) and prevent backward flow. The block of nozzle also diversify powder rate of cement. YSS (Youngil Special Silicate, YSS) that lowers $Na_2O$ and thereby increases durability was developed by gel-forming reaction material. The seepage state and unconfined compressive strength of the injection material using the special injection tip equipment was tested in this study. The results of this study showed that the uniaxial compressive strength, permeability, N-value, TCR and RQD were improved by this method. Engineering characteristics obtained by the special injection tip method will be compared with those by the other method through various field tests from now on.

• Journal of the Korean Geographical Society
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• v.49 no.1
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• pp.91-105
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• 2014

The objective of this study is to analyze the project performance and development process of the phase 1 project of GFEZ from 2004 to 2010. The phase 1 project from 2004 to 2010 is consist of eleven project zones. Among these zones, eight zones are currently underway and three zones have been completed. The performance of the phase 1 projects is no so much because it were stated later than planning with the difficulty of business developers selection. The major performances are development and supply of industrial & residential land, construction of road and railway, investment promotion of 102 companies, and creation of 20,971 new jobs. Most of the direct invested companies were located at Gwangyang and Yulchon Districts, and were mainly logistics and related service, iron and steel, machinery, shipbuilding, and fine chemicals. The main problems, however, are the limit of promotion of high-tech industries and large firms, low FDI reported rate, difficulty of superior business developers, delayed business progress of Hadong district. Therefore, efforts to solve these problems are required for the success of GFEZ.

• Korean journal of communication and information
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• v.36
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• pp.7-41
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• 2006

This study criticizes the wave of liberalization, privatization, thoughtless and uncontrolled over-competition in the electronic communication networks area. This criticism is based on the 'transport economics' on one side, the 'network neutrality debate' on the other side. Through these standpoints, this study insists that it needs to deal with a social agenda related to the problems such as unplanned and unbalanced development of electronic communication networks, double/tripple-investment in the communication industry, conflicts among network companies and the decline of public values. Also does this study stress on the new ideas in the electronic communication network policy and planning to manage these problems. Electronic communication networks are converging and their borders are blurred. As a result of these flows, the field of information technology, media and contents is faced with radical changes. These changes could be so critical and complicated that nobody can diagnose their multi-level implications. However, the one thing sure is that we should start from the communication networks to think and control a communication system. Therefore, we should discuss and plan the now-and-future of communication infrastructure and its management. we need not only a market mentality but also a socio-cultural mentality. In this respect, this study does insist that it requires the vision of digital democracy and democratic communication ecology to put the steps toward social communication system.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.467-467
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• 2016

암거는 일반적으로 용수나 배수용의 수로가 도로, 철도, 제방 등의 아래에 매설 된 수로를 지칭한다. 이러한 암거는 산업발전으로 사회기반시설의 신설 및 확충, 재정비 등으로 많이 활용되고 있다. 최근 들어 기후로 인한 재해가 급증하면서 이러한 시설물에 대한 안정성 및 관리에 대한 관심이 높아지고 있는 것이 현실이다. 특히 소하천은 집수면적 및 유로연장이 짧고 하상경사가 급하기 때문에 홍수에 취약하다. 즉, 빨라진 유속으로 인해 구조물 주변의 세굴에 의한 유실, 토사유출로 인한 하상퇴적, 부유물로 인한 차단으로 인해 통수에 지장을 받아 피해가 발생하게 된다. 이러한 암거시설물 피해는 2차 피해로 이어질 수 있으며 사회기반시설 파괴로 도시기능이 마비되고 인근 주변지역에 침수로 인한 재산 및 인명피해까지 발생시킬 수 있는 피해 잠재능력을 보유하고 있다. 그러나 피해에 대한 예방대책은 유지관리를 통해 지속적으로 관리하는 것이 대부분의 지침 등에 소개된 내용들이다. 본 연구에서는 암거를 대상으로 암거의 폐색으로 인해 암거주변에서 변화되는 흐름특성을 축소모형을 통해 검토하고자 하였다. 암거 축소모형실험은 1.5m 폭을 갖는 직선수로에서 수행하였으며, 암거모형은 도로암거표준도(2008)를 참조하여 $3m{\times}3m$ 수로암거를 대상으로 1/10 축소모형을 제작하였다. 암거유입부 퇴적으로 인한 암거의 차단률(차단면적/암거단면적)은 차단이 발생하지 않는 0% 조건에서부터 10%, 20%, 30%, 40%, 50% 조건에 대해 실험을 수행하였다. 실험결과 차단에 따른 암거 상류단의 수위는 차단이 없는 암거의 경우에 비해 차단율이 높아질수록 암거유입부 수위는 20.4% ~ 82.7% 상승하는 것으로 나타났다. 암거의 차단률이 40% 이상일 경우 높아진 수위로 인해 암거통로의 윗상면부까지 다다르고 있으며 50%일 경우 암거를 통과하는 흐름이 자유수면흐름이 아닌 오리피스 흐름이 발생하는 것으로 나타났다. 암거유입부 차단으로 인한 암거주변의 최대유속은 암거 직하류부에서 주로 발생하여 암거 유출부에서의 최대유속은 차단율이 증가할수록 선형적으로 증가하는 것으로 나타났으며 암거 유출부에서의 유속은 차단전의 조건(0%) 대비 4.2% ~ 35.5% 까지 상승하는 것으로 나타났다. 이와 같은 결과를 토대로 고려하였을 때 대부분 산지부에서 설치되는 암거의 경우 유속이 불가피하게 증가하게 됨으로 유속에 따른 유속조절방안(차단 및 우회시설) 및 세굴대책을 세워야 할 것으로 판단된다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.325-337
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• 2021

On the road and rail tunnels, the evacuation pathway and facilities such as smoke-control and fire suppression system are essential in tunnel fire. In the long twin tunnels, the cross-connection tunnel is usually designed to evacuate from the tunnel where the fire broke out to the other tunnel. In twin shield tunnels, the segment lining has to be demolished to construct the cross-connection tunnel. Considering the modern shield TBM is mostly the closed chamber type, the exposure of underground soil induced by removal of steel segment lining is the most danger construction step in the shield tunnel construction. This case study introduces the excavation method using the thrust of large steel pipe and reviews the measured data after the construction. The large steel pipe thrust method for the cross-connection tunnel can stabilize the excavated face with the two mechanisms. Firstly, the soil in front of excavated face is cylindrically pre-supported by the large steel pipe. Secondly, the excavated face is supported by the plugging effect caused by the soil pressed into the steel pipe. It was reviewed that the large steel pipe thrust method in the cross-connection tunnel is enough to secure the construct ability and stability in soil from the measurement results about the deformation and stress of steel pipe.

• Korean Journal of Construction Engineering and Management
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• v.20 no.3
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• pp.3-11
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• 2019

The construction of a facility is an act whereby infrastructure such as roads and railways and other facilities such as housing and office spaces are constructed, and due to the characteristics of the relevant industry where such construction is carried out in a custom order method, it requires a long period of time mostly. While the construction is carried out over a long period of time, fluctuations in the price of raw materials required for the construction occur. Therefore, the cost of the construction also fluctuates inevitably. The fluctuation of the construction cost meshes closely with the profit of a constructor and the efficiency of government spending. Therefore, it is necessary to maintain the construction cost at a reasonable level by adjusting the construction cost rationally in order to secure the required construction quality and spend the budget efficiently. The buffer system for solving such problem is the contract amount adjustment system by fluctuations in prices (Escalation/De-Escalation). In this study, the method combining the escalation method based on the item adjustment method was suggested for an efficient contract amount adjustment method. In addition, it is proposed that there be an investigation and codification of matters not applied to government acts and regulations on contracts related to the adjustment of fluctuations in prices legally.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.77-88
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• 2006

In this study, the lateral behavior of Pile-Bent structures subjected to lateral loading was evaluated by a load-transfer approach. An analytical method based on the Beam-Column model and nonlinear load transfer curve method was proposed to consider material non-linearity (elastic and yielding) and $P-{\Delta}$ effect. Special attention was given to the lateral deflection of Pile-Bent structures depending on different soil properties, lateral load, slenderness ratio based on pier length and reinforcing effect of casing. From the results of the parametric study, it is shown that the increase of lateral displacement in a pile is much less favorable for an inelastic analysis than for an elastic analysis. It is found that for inelastic analysis, the maximum bending moment is located within a depth approximately 3.5D(D: pile diameter) below ground surface, but within 1.5D when $P-{\Delta}$ effect is considered. It is also found that the magnitude and distribution of the lateral deflections and bending moments on a pile are highly influenced by the inelastic analysis and $P-{\Delta}$ effect, let alone soil properties around an embedded pile.