• Safety and Health at Work
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• v.15 no.1
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• pp.17-23
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• 2024

Background: The present study aimed to analyze several aspects of the working conditions and health status of platform workers in the Republic of Korea, such as ergonomic and emotional hazards. We also compared the health status of the platform workers with that of the general population. Methods: A total of 1,000 platform workers participated in this survey from August 7 to August 17, 2022. The participants included 400 designated drivers, 400 food-delivery drivers, and 200 housekeeping managers. A face-to-face survey with a structured questionnaire was conducted by researchers who had received specific instructions. The focus of the survey extended to the work environment, encompassing factors such as workplace violence, as well as physical, chemical, and ergonomic hazards. Health-related data for the previous year were also collected, covering a range of issues such as hearing problems, skin problems, musculoskeletal symptoms, headaches, injuries, mental health issues, and digestive problems. Subsequently, we compared the health symptom data of the responders with those of the general population in the Republic of Korea. Results: Platform workers, including designated drivers, food-delivery drivers, and housekeeping managers, existed in the blind spot of social insurance, facing frequent exposure to physical and chemical hazards, ergonomic risk factors, and direct or indirect violence. The prevalence of health problems, including musculoskeletal symptoms, general fatigue, and depressive symptoms, in each occupational group was statistically higher than that in the general population after standardization for age and gender. Conclusion: The results revealed unfavorable working environment and inferior occupational health of platform workers compared with those of the general population.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.151-157
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• 2008

It is difficult for existing beams to ensure the sufficient embedding depth due to constructional cause. Owing to these problems, currently FRP-Rod embedding repair method run parallel with a section increasing method in many case. In this study, anchor pin was adopted to solving the problems of the sliding of FRP-Rod and the unified behaviors of the repaired beam without increasing the section. In the experiments, split failure of covering concrete and slippage of the FRP-Rod were not occurred. it was confirmed that FRP-Rod shown the integrate behaviors with RC beam till the repaired beams destroyed.

• The Korean Journal of Ecology
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• v.23 no.4
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• pp.339-345
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• 2000

Heilongjiang Province has set up 104 nature reserves, with a total area of 2,641,700 ha, or 5.88% of the total area of the province. These constitute a network of nature reserves comprising most important types of nature reserves. and play an active role for improving the protection of the ecological environment and for the continuous economic and social development of the province. But in the management of these nature reserves, there are still some problems with people's idea, with educating the public, and with capital investment. These problems should be treated seriously. To preserve our natural heritage and biodiversity and to promote the sustainable development of our society and economy, it is projected that by the year 2000. the number of nature reserves in Heilongjiang is to reach 109, covering 6.17% of the total land area of the province. This percentage will be further increased to 8.62% by 2010, at which time the network of nature reserves is to have a proper distribution and comprehend all the important types of nature reserves. This will ensure the healthy development of the cause of nature conservation. with systematic planning, active protection. and sustainable use, so that ecological and social benefits can be developed hand in hand with economic benefits.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.6
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• pp.716-724
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• 1998

The purpose of this study is to investigate the washing methods specified on care labels of blue jeans and to examine the appropriateness of the specification. In the study, the present condition of care labels on 100% cotton blue jeans was investigated and the consumers' washing methods of blue jeans were surveyed. Also, the shrinkage of blue jeans after washing was measured. The major results were as follows: 1. In spite of the fact that same materials of 100% cotton denim were used in all cases, washing signs on care labels showed very differently and the symbols of hand wash, using light duty detergent, no wring, drying in shade, and warm ironing with a covering cloth were demanding too high level of care for the protection of blue jeans. 2. Almost all consumers didn't follow instructions proposed on care labels because they didn't anticipate problem. In reality, most consumers washed blue jeans by machine in cold water with heavy duty detergent at standard course, dried under the sun, and didn't iron. The 40.8% of consumers didn't have problems even if they didn't follow instructions. Most problems happened after washing were shrinkage in length, but in shrinkage test after 15 times washings, it was found that there was no serious shrinkage problem. 3. For ideal care of blue jean, it is necessary for manufacturers to recognize the importance of care label and to stick correct appropriate care label. Also, consumers have to trust and follow instructions on care label.

• Korea journal of population studies
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• v.12 no.1
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• pp.19-29
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• 1989

It is well known that vital statistics is of great importance as basic data for establishing various range of national policies. Especially, vital statistics is important among demographic information for monitoring and evaluating the population policy, for constructing life table, for making population projection, and for studying various aspects of the society. In principle, the production of vital statistics is based on the registration system. It is, however, still observed that there are some limitations in utilizing fully the registration system due to the inherent problems such as problems in its coverage, accuracies and timeliness. Thus, as an alternative, many countries conduct survey on vital statistics in order to supplement the registration system and obtain in-depth data. Korea is no exception in this aspect. The National Bureau of Statistics carries out the so-called Continuous Demographic Survey. This is a kind of multi-round retrospective survey, covering 32, 000 households and having reference period of one month. The survey has also characteristics of multi-subject sample. Thus, surveys on economic activity status of population, house-hold income & expenditure, and social indicators are together conducted with the same sample. It is, however, found that the survey itself tends to have some quality problems. Especially, the quality problems connected with field data collection are summarized as coverage error, non-response error and response error. Although it is inevitable not to be free from these errors, we should make all our efforts to reduce the errors. The probable schemes pointed out in this paper are as follows : 1) the strengthening formal quality control activities, 2) the review of the survey method, i. e., the combining interview method with mail-sending and mail-back method or pick-up method, 3) well documentation for various cases found in every stage of data collection, and 4) the strengthening the analytical activities. It is, also, emphasized that sincerity of planners and interviewers is the most important factor among other things.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.425-431
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• 2014

Most fields in highland areas are covered with rye or hairy vetch for conservation during a fallow. However, using cover crops needs an effort to sow, and this makes top soil more vulnerable to loss due to surface disturbances. The aims of this study were to develop an automatic seeding-regulator device using a low-price, extensive-use GPS sensors and a DC motors and to evaluate a working efficiency of it after adaptation to partial tillage machine for reducing seeding effort. The amount of runoff water and soil loss was evaluated with partial tillage and simultaneous-seeding after harvesting soybean, in 17% slope lysimeters. In results, the seeding amount with the machine speed was stable between $0.5{\sim}0.8m\;s^{-1}$ of working sections. The automatic control device of seeding-rate could be enough to solve the slip problems of power selecting supply system or five four-wheel drive device. In partial tillage and simultaneous seeding, runoff water was 11.6% ($1.8m^3ha^{-1}$) of the scatter-seeding control ($15.5m^3ha^{-1}$) and soil loss was 13.2% ($7kg\;ha^{-1}$) of the scatter-seeding control ($53kg\;ha^{-1}$). These results suggest that partial tillage and simultaneous-seeding methods are very effective in decreasing work effort and soil loss of sloped land.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.88-97
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• 2009

In these days, it attracts our attention to create a green outdoor environment around the building block in urban area. Green space and permeable ground covering are increased by laws and regulations. According to these trends, variety researches for improving outdoor environment are accomplished at this moment. However, the problems for outdoor environment such as heat island effect and air contaminant in urban area are still reported. The purpose of this study is to examine the variables to affect the formation of outdoor thermal environment by quantitative analysis. As a initial study, in this paper, the effect of ground composition on changes of surface temperature and heat flux in multi-residential building were analyzed by field measurement and numerical simulation. Through field measurement, the surface temperature and heat flux of artificial ground in multi-residential building in Suwon city were measured. The result showed that the surface temperature was decreased by about $20^{\circ}C$ with afforestation of artificial ground compared with those of concrete covering. Moreover, the inner temperature of artificial ground was changed as same behaviors of outdoor temperature changes to depths of 20cm. In simulation, the effect of soil types and depth of artificial ground on the changes of the surface temperature and heat flux were analyzed. As results, the natural soil ground was more effective against lowering the surface temperature than any other cases in the analyzed cases.

• Archives of Plastic Surgery
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• v.40 no.3
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• pp.209-213
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• 2013

Background A cartilage wedge block and covering flap are standard procedures for firm elevation of the ear in microtia correction. However, using costal cartilage for elevation of the reconstructed auricle can be insufficient, and the fixed cartilage wedge block may be absorbed or may slip out. Furthermore, elevating covering flaps is time-consuming and uses up fascia, a potential source of reconstruction material. Therefore, we propose an innovative method using autologous onlay rib bone graft for auricular elevation of microtia. Methods From February 1995 to August 2012, 77 patients received a first stage operation with a rib cartilage framework graft. In the second stage operation, a small full thickness of rib bone was harvested through the previous donor scar. The bihalved rib bone was inserted into the subperiosteal pocket beneath the cartilage framework. Results The follow-up time ranged from 1 month to 17 years, with a mean of 3 years. All of the patients sustained the elevation of their ears very well during the follow-up period. Donor site problems, except for hypertrophic scars, were not observed. Surgery-related complications, specifically skin necrosis, infection, or hematoma, occurred in 4 cases. Conclusions Onlay rib bone graft used to elevate the reconstructed auricle is a more anatomically appropriate material than cartilage, due to the bone-to-bone contact between the bone graft and the temporal bone. Postoperative minor correction of the elevation degree is straightforward and the skin graft survives better. Therefore, reconstructed auricle elevation using onlay rib bone graft is a useful and valuable method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.192-196
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• 2005

Key part of main equipment in a gas turbine may be likely to be damaged due to operation under high temperature, high pressure, high-speed rotation, etc. Accordingly, the cost for maintenance increases and the damaged parts may cause generation to stop. The number of parts for maintenance also increases, but diagnostics technology fur the maintenance actually does not catch up with the demand. Blades are made of precipitation hardening Ni superalloy IN738 and the like for keeping hot strength. The surface of a blade is thermal-sprayed, using powder with main compositions such as Ni, Cr, Al, etc. in order to inhibit hot oxidation. Conventional regular maintenance of the coating layer of a blade is made by FPI (Fluorescent Penetrant Inspection) and MTP (Magnetic Particle Testing). Such methods, however, are complicated and take long time and also require much cost. In this study, defect diagnostics were tested for the coating layer of an industrial gas turbine blade, using an infraredthermography camera. Since the infrared thermography method can check a temperature distribution on a wide range of area by means of non-contact, it can advantageously save expenses and time as compared to conventional test methods. For the infrared thermography method, however, thermo-load must be applied onto a tested specimen and it is difficult to quantify the measured data. To solve the problems, this essay includes description about producing a specimen of a gas turbine blade (bucket), applying thermo-load onto the produced specimen, photographing thermography images by an infrared thermography camera, analyzing the thermography images, and pre-testing for analyzing defects on the coating layer of the gas turbine blade.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.27-35
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• 2009

Integer programming is a very effective technique for searching optimal solution of combinatorial optimization problems. However, its applicability is limited to linear models. In this paper, I propose an effective method for solving a nonlinear optimization problem by integrating the powerful search performance of integer programming and the flexibility of neighborhood search algorithms. In the first phase, integer programming is executed with subproblem which can be represented as a linear form from the given problem. In the second phase, a neighborhood search algorithm is executed with the whole problem by taking the result of the first phase as the initial solution. Through the experimental results using a nonlinear maximal covering problem, I confirmed that such a simple integration method can produce far better solutions than a neighborhood search algorithm alone. It is estimated that the success is primarily due to the powerful performance of integer programming.