• Journal of the Korean Society of Radiology
• /
• v.9 no.1
• /
• pp.17-21
• /
• 2015

Recently, As people's interest in the health of teeth is increased in the medical field changed into aging society, the number of times for the radiological diagnosis is increased. It can be said that the radiation exposure dose of Korean population is increased. It is also growing concern about radiation exposure. Therefore, the basic data for the dental panoramic X-ray system, its investigation and measuring the radiation dose is needed. In this study, we used ALOKA PDM-117 dosimeter and estimated a two-dimensional dose distribution of the dental panoramic X-ray system (VATEC Pax-400). Dose evaluation about the distribution is confirmed from the point of radiation exposure of a patient. Dose distribution of the dental panoramic X-ray system irradiated chin and the facial region to high dose as well as the parts of teeth. It was founded that the eye lens which are sensitive to radiation are exposed to unnecessary radiation, considering the effect of scattered radiation. The results of this study will be used more accurate dose assessment in a variety of object size and location of measuring dose.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.62 no.2
• /
• pp.53-62
• /
• 2020

The purpose of this study is to estimate the channel water loss of agricultural water supply in the command areas belong to Yechon irrigation channel of Gyeongcheon reservoir located Mungyeong-si, which area experienced a severe drought in 2015. The channel water loss was estimated by comparison of the irrigation water requirements (IWR) and agricultural water supply of the field data from 2012 to 2015. Further analysis was conducted to define the conveyance loss estimated based on the leakage holes and illegal pumping spots investigated through the field survey, and the distribution loss obtained by subtracting conveyance loss from the channel water loss. The annual rainfall decreased gradually, but the contribution of effective rainfall, available rain water to crop, increased to IWR during the study period. These phenomena resulted in the increase of agricultural water supply, and hence made greater the channel water loss simultaneously. The average channel water losses estimated as 36.8 % with 7.1 % of the conveyance loss and 29.7 % of distribution loss respectively. The distribution loss seems to be related to total number of rainy days, and irrigation schedules, while the conveyance loss was caused by irrigation channel aging conditions and illegal intake problems. In order to achieve sustainable agricultural water resources, the channel water loss needs to be reduced through the restoration of aged irrigation facilities and effective water managements in the fields.

• Journal of the Korean Magnetics Society
• /
• v.3 no.3
• /
• pp.229-233
• /
• 1993

The effects of differential partial pressures of oxygen during sputtering on the magnetic and recording characteristics of magneto-optical disks were investigated. Different flows of oxygen were deliberately introduced into the sputtering chamber to have a variety of partial pressures of oxygen during sputtering. A residual gas analyzer was employed to monitor the oxygen peak before, during, and after sputtering and to estimate the reacted oxygen amount. Most of the oxygen introduced into the chamaber was reacted during sputtering. As the partial pressure of oxygen increased, the oxygen content of the TbFeCoCr film increased also. The oxygen appeared to be bound as Tb-O, effectively decreasing the magnetically active Tb content of the film The coercivity decreased but the squareness of the Kerr hysteresis loops was still excellent. The perpendicular anisotropy was not significantly affected by oxygen amount. The carrier-to-noise ratio, includi!1g the write power sensitivity and bias field sensitivity did not change too much with oxygen content in the film The disks sputtered with oxygen showed better bias field sensitivity with lower write power threshold than the disk sputtered without oxygen, due to high demagnetization during domain formation. No significant degradation of coercivity for the disk sputtered oxygen was observed during an accelerated aging test.

• Journal of the Korean GEO-environmental Society
• /
• v.17 no.9
• /
• pp.47-52
• /
• 2016

Unusual extreme weather events, which exceed a safe design capacity of the infrastructure, increase the frequency of natural disasters and has also been enlarged damage scale. Aging buildings and rapid urban progress act as weighting factors for the new composite disasters. Technological advances support detecting pre-disaster risk, real-time data analysis, and rapid response to the disaster site, but it is insufficient that emergency relief for buried alive must take advantage of the proven technologies through field tests. This study aims to evaluate directional drilling performance through underground soils and the reinforced concrete structure for primary lifeline installation in order to quickly provide relief supplies for buried alive when urban structures collapse.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.4
• /
• pp.121-125
• /
• 2018

This paper presents the assessment of 7-wire strand monitoring using acoustic emission technique for bridges. 7-wire strand is widely used construction materials to provide additional tensile force to bridges. PSC (PreStressed Concrete) bridge and cable-stayed bridge are representatives for such cases. However, as the bridge aging progresses recently, corrosion problems of strand are emerging. For this reason, various NDT (Non-Destructive Test) methods for cable inspection are being studied and applied to the field. One of the NDT methods, acoustic emission technique, is known as an effective technique to detect cable damage and breakage. In this study, to evaluate the applicability of acoustic emission technique to bridges, acoustic emission signals according to damage of the strand were acquired and analyzed by tensile test. Moreover, The optimal AE sensor type was selected for field application. As a result, it is considered that the acoustic emission technique will be able to detect corrosion breakage and signs of rupture.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.29 no.2 s.43
• /
• pp.131-147
• /
• 2003

In the 21st century, the development of cosmetics is led to pursue the high functionality of cosmetics with excellent effectiveness and safety. As Cosmetic Act took effect in 2000, functional cosmetics is provided in the law. As a result, the research and development of functional cosmetics has continually increased, and the number of patent applications in functional cosmetics has also rapidly increased as a plan for preoccupying in the functional cosmetics age. Now, the cosmetic industry has a great interest in developing anti-wrinkle cosmetics among functional cosmetics, because women's desire for having young resilient skin has increased since Korea entered an aging society thanks to the advanced medical technology. The patent application trends of anti-wrinkle cosmetics at home since 2000 particularly show the rapid increase in the applications in natural plant extracts. It may be because Korean consumers preference of vegetable cosmetics has resulted in the development of raw materials based on the traditional medicine. As for the existing preparation such as Retinoid or Ascorbic acid, the patent application itself will be an essential technical element in the future because patent applications are filed in the field of a preparation of cosmetics for stabilizing ingredients, reducing skin irritability or promoting absorbance, and in the field of cosmetic formulation technology. As there are many studies on the causes of skin wrinkles, it is expected that new raw materials of cosmetics can be developed due to new mechanisms, and that the number of patent applications in new technologies will increase due to a change in the thought of cosmetics accompanied by the integration of cosmetics with biotechnology using Genetic Engineering, including the practical application of the medicine previously used far treating skin diseases to an anti-wrinkle agent and the mass production of active ingredients of cosmetics.

• Journal of the Korean housing association
• /
• v.20 no.6
• /
• pp.89-99
• /
• 2009

The purpose of this research is to determine the deterioration characteristics of high-rise and high-density apartment complexes in 1st period new towns in order to regenerate apartments as sustainable residential environments in Korea. For this purpose, the level of deterioration was evaluated by using 'evaluating indicators of the level of deterioration of high-rise and high-density apartments'. The deterioration characteristics were determined inclusively and concretely based on evaluation results. In addition, the deterioration level according to residents' awareness of the deterioration of their apartment was evaluated. This study was conducted by methods of field data collection, staff interview, field measurement, and resident survey according to the measurement of the evaluating indicators. And the re-organized questionnaire based on the evaluating indicators was utilized for a survey of resident's awareness. The results are as follows: In the physical dimensions of apartments, the deterioration characteristics included deteriorated equipment and a decline in structural performance due to the aging of the apartment, a shortage of parking spaces, and the low flexibility of the bearing wall structure, etc. In terms of the social dimensions, the apartments showed an increase in the number of elderly households, a shortage of community facilities, and a lack of the opportunity for community participation etc. In terms of the economic dimensions, the apartments showed limitations in maintenance & repair and a lack of environmentally friendly features.

• KIEAE Journal
• /
• v.3 no.3
• /
• pp.43-50
• /
• 2003

Nowdays the apartment is a main type of modernized residential buildings. According to the improvement of construction techniques and functions of windows and doors, recent apartments are enhanced air tightness of windows, doors and building envelopes. As Infiltration is decreased and natural ventilation is reduced, energy could be saved in winter. However, indoor air quality is bad. The air Infiltration of a building could be enlarged by physical actions, such as building designs, constructions and reduction of air tightness which is caused by aging. This research analyzes and measures with KNS-4000P (Sapporo air tightness measurement) the air tightness of the high rise apartments which is recently constructed and not occupied yet. With depressurization method, the KNS-4000 installed on the window and the indoor air-leakage was measured. At that time, Air come out from the edge of the windows and doors because of the pressure differences between indoor and outdoor. We measure the amount of the air as effective air leakage areas. This method of depressurization takes less time to measure than other methods and is less affected from other conditions. We measured infiltration of total 56 household, 29 households S apartment (total floor area : $64.42m^2$) in Balan and 29 households D apartment(total floor area : $78.21m^2$) in Chonan. As a result of the field measurements at October 2003, normalized leakage area of D apartment in Cheonan was $2.05cm^2/m^2{\sim}3.49cm^2/m^2$ (average: $2.77cm^2/m^2$) and normalized leakage area of S apartment in Balan is $1.23cm^2/m^2{\sim}1.68cm^2/m^2$ (average: $1.5cm^2/m^2$).

• Smart Media Journal
• /
• v.6 no.2
• /
• pp.33-41
• /
• 2017

Railway point machines act as actuators that provide different routes to trains by driving switchblades from the current position to the opposite one. Since point failure caused by the aging effect can significantly affect railway operations with potentially disastrous consequences, replacement detection of point machine at an appropriate time is critical. In this paper, we propose a replacement condition detection method of point machine in railway condition monitoring systems using electrical current signals, after analyzing and relabeling domestic in-field replacement data by means of OLAP(On-Line Analytical Processing) operations in the multidimensional data cube into "does-not-need-to-be replaced" and "needs-to-be-replaced" data. The system enables extracting suitable feature vectors from the incoming electrical current signals by DWT(Discrete Wavelet Transform) with reduced feature dimensions using PCA(Principal Components Analysis), and employs SVM(Support Vector Machine) for the real-time replacement detection of point machine. Experimental results with in-field replacement data including points anomalies show that the system could detect the replacement conditions of railway point machines with accuracy exceeding 98%.

• Korea journal of population studies
• /
• v.9 no.2
• /
• pp.30-41
• /
• 1986

It is worthwhile to compare the major social indicators between Korea the and Taiwan particularly focusing on population because two countries share close similarities in many aspects and gave access to the advanced level among the developing countries in recent years. Similarities or dissimilarities presented in this paper will be helpful to the researchers and the policy makers of the two countries by giving them insight on the situation. The similarities and dissimilarities between the two countries in the field of demography and social indicators are summarized as follows : 1. Similarity indicators can be found in fertility. One of them is Net Reproduction Rate and it was less than one in both countries in 1985. The past trend of fertility, in fact level and pattern of it, of the two countries from 1960 to 1985 has been very similar. 2. Level and pattern of mortality is quite different between two countries. Mortality level of Taiwan is lower than that of Korea. 3. The close similarity between two countries was shown in population structure and aging index. 4. On future population projection, the population structure and the level and pattern of fertility of the two countries are very similar. During fourty years, the period from the current population growth rate which is a little more than 1% to the zero growth rate, the annual population growth rate of the two countries is approximately 0.6% and that is similar to those of the current industrialized countries. According to the medium variant of the projection, Korean population will reach Zero Growth Rate between 2020 and 2025 whereas Taiwan between 2025 and 2020 5. Current level of contraceptive prevalence of both countries is very similar showing above 70% of the eligible women in 1985 and one of the valuable factors of achieving this high rate within short period must be the national program of the family planning. A close cooperation in the field of population policy formulation and its implementation is indispensable because Korea and Taiwan have similarity in many population indicators.