• Korean Journal of Construction Engineering and Management
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• v.8 no.3
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• pp.97-105
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• 2007

In many construction projects, such as dams, highways, airports, buildings, industrial plants, and sewerage and drainage systems earthmoving operation is defined the movements of a certain quantity of earth to alter the surface configuration or conditions so that projects requirement can be met. Accurate calculation of travel time is essential for determining productivity of earthmoving operations, and for ultimately selecting the most cost-effective fleet configuration for executing the work. Also transportation work that utilizes dump truck consists average So in the whole expenses earthmoving operation, and is an important cost factor for cost management. Therefore this study proposes a methodology for optimum transfer speen based on the analysis of factors affecting earthmoving operation in different road types by collecting the sources of dump truck running speeds and considering the main factors affecting the earthmoving operation.

• Journal of Radiation Protection and Research
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• v.34 no.4
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• pp.176-183
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• 2009

Maintenance on the water chamber of steam generator during outage in nuclear power plants (NPPs) has a likelihood of high radiation exposure to whole body of workers even short time period due to the high radiation exposure rates. In particular, it is expected that hands would receive the highest radiation exposure because of its contact with radiation materials. In this study, characteristic analysis of inhomogeneous radiation fields for contact operations was conducted using thermoluminescent dosimeter (TLD) readouts from the application tests of two-dosimeter algorithm to Korean NPPs in 2004. It is regarded that inhomogeneous radiation fields for contact operations in NPPs are dominated by high energy photons. In addition, field tests for workers who participated in maintenance on the steam generator during outage at Ulchin NPPs in 2009 and pressure tube replacement at Wolsong NPPs in 2009 were conducted to analyze radiation fields and to estimate the extremity dose. As a result, radiation fields were dominated by high energy photons.

• Journal of Korean Society of Forest Science
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• v.76 no.4
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• pp.348-356
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• 1987

A new simple method to estimate the earth quantity which is basic data for making the plan of mountain forest road is tried to develop as one of ways to reduce time cost of plan making. The zero-line surveying method, the concept of 2/3 road width in cut-away part and of same quantity between cut-away and fill-up earth which are the backgrounds to develop this method is introduced and explaned also it's theoritical propriety. Under the precondition which have to apply above concepts for constructing the mountain forest road the exchange table for estimating the earth quantity is made like table 3 and 4 through being calculated by a trigonometric function. Table 3 can be used to estimate the earth quantity on the cut-away road-width according to slope of terrain and different road-width, and table 4 can be applied to calculate the quantity of cut-away earth when to know the road-width of cut-away. When using these tables the performance of field surveying and office work for road plan will be highly increased.

• Korean Journal of Construction Engineering and Management
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• v.14 no.1
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• pp.124-132
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• 2013

An influx of the population to the city has soared due to industrialization. As times go by, cities become densely populated so Korean government started to construct a number of buildings including apartment housings. Because they have become functionally, structurally, esthetically deteriorated over the past two decades. some improvements are needed. There are mainly two ways to improve old buildings: remodeling and reconstruction. Between the two, the first one is more popular as it is less time-consuming and more eco-friendly. Demolition work comes first for both of them and it should not give negative effects since it is regarded as a CP(Critical path) in the overall process. For this reason, a thorough construction management must be done. The reality, however, demolition is managed by the construction manager's experiences and decisions. If the key factor of demolition which is the planning of manpower and machine equipment, is determined by unscientific and subjective judgments, its period and risk also will increase. In particular, eco-friendly demolition can be more risky because it's been rarely conducted. Therefore, scientific and objective ways of demolition management are needed. In this context, this paper aims at analyzing productivity in each process of demolition focusing on manpower and machinery equipment which are the main parts of demolition assuming that the demands of eco-friendly remodeling demolition projects will be increasing. At the same time, by estimating working period through the output, this paper would be helpful to set up the plans for overall project in earlier stage.

• Journal of Agricultural Extension & Community Development
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• v.19 no.4
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• pp.1021-1039
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• 2012

Based on the ergonomic evaluation of workers in the domestic traditional Korean sweet manufacturer, one of the small scale agricultural product manufacturers, the purpose of this study is on estimating the specific works and muscles that have possibility of musculoskeletal disorder through an EMG experiment for quantitative evaluation. The method followed in an order: works that have musculoskeletal disorder risk were extracted through ergonomic assessment tools, RULA and REBA, and then EMG experiment on the postures was carried out with six healthy adult male patients. As an ergonomic evaluation result, work posture during the drying process had the greatest musculoskeletal disorder risk, and EMG activity in the cleansing work posture scored the highest among the drying, cleansing, and coating work postures. In particular in the drying work, relatively high EMG activities were shown in the two muscles in the lower body: biceps femoris muscle, and gastrocnemius, than any other muscles. Therefore, during the traditional Korean sweet workplace design in future, the workplace requires a posture that deeply bow wrist for a long time should be avoided.

• Safety and Health at Work
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• v.6 no.3
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• pp.174-183
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• 2015

The major purpose of this study is to construct a retrospective exposure assessment for benzene through a review of literature on Korea. Airborne benzene measurements reported in 34 articles were reviewed. A total of 15,729 individual measurements were compiled. Weighted arithmetic means [AM(w)] and their variance calculated across studies were summarized according to 5-year period intervals (prior to the 1970s through the 2010s) and industry type. Industries were classified according to Korea Standard Industrial Classification (KSIC) using information provided in the literature. We estimated quantitative retrospective exposure to benzene for each cell in the matrix through a combination of time and KSIC. Analysis of the AM(w) indicated reductions in exposure levels over time, regardless of industry, with mean levels prior to the 1980-1984 period of 50.4 ppm (n = 2,289), which dropped to 2.8 ppm (n = 305) in the 1990-1994 period, and to 0.1 ppm (n = 294) in the 1995-1999 period. There has been no improvement since the 2000s, when the AM(w) of 4.3 ppm (n = 6,211) for the 2005-2009 period and 4.5 ppm (n = 3,358) for the 2010-2013 period were estimated. A comparison by industry found no consistent patterns in the measurement results. Our estimated benzene measurements can be used to determine not only the possibility of retrospective exposure to benzene, but also to estimate the level of quantitative or semiquantitative retrospective exposure to benzene.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.4
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• pp.387-397
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• 2014

This work aims at estimating global warming potentials (GWP) of $CF_3Br$ and HFC-134a among green house gases. It has been reported that they have much higher GWP than $CO_2$ in the atmosphere. $CF_3Br$, halon 1301 which is well known to be a fire extinguisher, as one of the bromine-containing halons has been banned since 2003 due to destruction of ozone. HFCs, a kind of chiller which replaced chlorofluorocarbons (CFCs) are one of greenhouse gases regulated by the Kyoto Protocol. In this study, we produced GWPs of $CF_3Br$ and HFC-134a by calculating a life time and measuring an absorption cross section to obtain a radiative forcing (RF). Their absorption cross sections were measured by using Fourier-transformed infrared spectroscopy (FTS) with a gas cell filled with their certified reference materials at room temperature. As a result, the RFs of $CF_3Br$ and HFC-134a were 0.32 and $0.168Wm^{-2}ppb^{-1}$, respectively and the GWPs were calculated as 7989, 6076, 3903 for $CF_3Br$ and 3855, 1300, 656 for HFC-134a for the time horizon of 20, 100, 500 years, respectively. Overall, uncertainty of the estimated GWPs can be estimated to be about 2.6%. Our results were compared with those proposed by the previous studies (IPCC, 2007; WMO, 1999).

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.57-66
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• 2017

Self-weight consolidation test and soil property of dredged soil at Incheon habour route were analyzed to determine the initial dredging reclamation amount, reclamation depth, and estimating the required time of self-weight consolidation with calculation of the final planned height of dredging reclamation site. The moisture content, void ratio and ratio of volume change with elapsed time after throwing were estimated through Yano's empirical equation. As a result, there was a less variation in elements when fine-grained soil content was low as similarly to the behavior of coefficient of sedimentation-consolidation, Cs and the highest variation was shown at the fine-grained soil content of 50%. The retention ratio according to the fine grained soil content that could reinforce the comprehensive aspect of retention ratio for each particle size presented in the standard of estimate for reclamation construction work was calculated and presented using the calculated ratio of volume change.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.259-274
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• 2005

In this paper, we propose a methodology to estimate the number of users in e-Commerce systems. There have been a lot of previous work under the closed-LAN system environment. But the study on the number of acceptable users in real network environment is hard to find in the literature. Our research applies a Hybrid Simulation by using QoS results for end-to-end high-speed Internet service, and experiments are performed with regard to LAN and WAN, network equipments, and various network bandwidth. As result of the experiments we observed that the response time of high-speed Internet service media(Wireless LAN, ADSL, Cable, VDSL) depends heavily on the sequence and depth of transactions and on the ratio of transactional and non-transactional interactions. That is, as the network and application get more loads, the number of acceptable users decreases. By adding a cache server and an L4 switch to the simulation model, we analysed the changes in the number of users and client response time.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.1
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• pp.85-91
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• 2001

Background : It goes without saying that cumulative trauma disorders is spreading to various types of occupation in many advanced countries including America, and it forms considerable rate of total occupational disorders already. and as the result of it, the seriousness of worker health problem and economic loss owing to production loss, recuperation expense, etc. are on the increasing trend through whole society. In case of Korea, the related measures as well as accurate fact-finding survey data on cumulative trauma disorders aren't prepared in detail, so it implies forward problem would be serious. Purpose : The purpose of this study is to draw the risk factor of cumulative trauma disorders in production factory, to forecast the rate of occurrence of cumulative trauma disorders on the basis of subjective symptoms, and to present forward realistic and effective prevention measures by showing the risk of cumulative trauma disorders, objecting the production factory of a domestic riding automobile assembly shop, by estimating in the aspect of human-engineering through the analysis of risk factor being a cause of cumulative trauma disorders. Methods : For this study, I investigated work type and on-duty hours, breathing time, and subjective symptoms of cumulative trauma disorders through questionnaire, objecting the workers in press. car body, coating, and outfit factory. Results : As a result of research, 81.2% of workers were in the physical burden due to present working, and the highest prevalence by part of body is an waist. The higher a rule score, The higher the number of workers complaind for working intensity, and the higher age work duration, tool used time, the higher prevalence of subjective symptoms by part of body. The number of workers complaind subjective symptom for treatment is the highest in drugstore.