• Journal of Radiation Protection and Research
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• 제47권1호
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• pp.39-49
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• 2022

Background: For proper monitoring of the eye lens dose, an appropriate calibration factor of a dosimeter and information about the mean energies of X-rays are indispensable. The scattered X-ray energy spectra should be well characterized in medical practices where eye lenses of medical staffs might be high. Materials and Methods: Scattered X-ray energy spectra were experimentally derived for three different types of X-ray diagnostic and therapeutic equipment, i.e., the computed tomography (CT) scan, the angiography and the fluoroscopy. A commercially available CdZnTe (CZT) spectrometer with a lead collimator was employed for the measurement of scattered X-rays, which was performed in the usual manner. Results and Discussion: From the obtained energy spectra, the mean energies of the scattered X-rays lied between 40 and 60 keV. This also agreed with that obtained by the conventional half value layer method. Conclusion: The scattered X-rays to which medical workers may be exposed in the region around the eyes were characterized by means of spectrometry. The obtained mean energies of the scattered X-rays were found to match the flat region of the dosimeter response.

• Geomechanics and Engineering
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• 제33권3호
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• pp.243-259
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• 2023

Turkey is one of the most important earthquake regions in Europe. This region has been exposed to many earthquakes of different magnitudes from past to present. It is of great importance to determine the dynamic properties of the soils for structures to be built in earthquake zones. In order to minimize the damages that may occur, the behavior of the soils under repeated loads should be known and taken into consideration in the design. In this study, 4 different point borings were taken near active fault lines in the North Anatolian fault zone (NAFZ). In order to determine the dynamic parameters of soils, both dynamic triaxial (TRX) and resonant column (RC) tests were carried out on undisturbed samples at every 5 m. As a result of the experiments, V_s and G_max values were obtained from the field and differences were determined. The dynamic behavior of the soil was examined at varying depths with the comparison of reference models in the literature and compatible results were obtained. Finally, the behavior at the transition region is highlighted. As a result, three shear modulus and dumping ratio models have been proposed for clay soils to be used in different soil conditions.

• Safety and Health at Work
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• 제14권3호
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• pp.243-249
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• 2023

Background: Southeast Asia has many people who work in the agriculture sector. Not many stakeholders pay special attention to the health of farmers, even though they are exposed to various types of hazards. One of the most common health complaints among farmers is related to work-related musculoskeletal disorders (WMSDs). This study aims to assess the prevalence of WMSDs and factors associated with them among farmers in Southeast Asia. Methods: A literature search on PubMed, ScienceDirect, Scopus, and EBSCO was conducted. Articles were included if they studied ergonomic problems among farmers from 11 countries in the Southeast Asia region and were published during 2015-2022. The Critical Appraisal Skills Program was used to evaluate the quality of the articles. The search process and retrieval process reflected PRISMA's recommendation. Result: There were 14 studies found from 3 countries that had published articles in PubMed and ScienceDirect, including Thailand [8], Indonesia [4], and Malaysia [2]. The prevalence of WMSDs in Thailand, Indonesia, and Malaysia was 78,31%, 81,27%, and 88,39%, respectively. Common factors associated with WMSDs include age, sex, smoking habits, drinking alcohol habits, working period (years), type of work, awkward position, non-ergonomic equipment, repetitive movements, and lifting heavy loads. Conclusion: The prevalence of WMSDs among farmers in Southeast Asia is considerably high. Effective intervention is essential for reducing the prevalence and protecting workers' health and well-being.

• Journal of Astronomy and Space Sciences
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• 제40권4호
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• pp.131-148
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• 2023

Lunar permanently shadowed regions (PSRs) never see direct sunlight and are illuminated only by secondary illumination - light reflected from nearby topography. The ShadowCam imaging experiment onboard the Korea Pathfinder Lunar Orbiter is acquiring images of these PSRs. We characterize and discuss the nature of secondary illumination for the Shackleton PSR from ShadowCam radiance-calibrated images. We also use modeling to understand the magnitude and direction of the secondary illumination. Results from our analysis highlight the non-homogeneous, dynamic, and complex nature of PSR secondary lighting. Knowledge of the direction of the secondary illumination is crucial for reli-able interpretation of contrasts observed in ShadowCam images. This preliminary analysis of the floor of Shackleton crater from images acquired over multiple secondary illumination conditions does not reveal indications of exposed surface ice, even though temperatures are constantly below 110K.

• 한국어류학회지
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• 제22권2호
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• pp.96-104
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• 2010

멸조위기종인 묵납자루 Acheilognathus signifer의 종복원을 위한 인공수정을 실시하는 과정에서눈과 피부의 색소발현이 결여된 백색증 개체가 출현하였다. 정상 묵납자루와 백색증 개체간 색소발현과 형태의 차이여부를 알아보기 위하여 몸통, 지느러미 눈 등 총 10개 부위에 대한 조직학적 검사를 실시하였다. 그 결과 정상 묵납자루의 경우, 멜라닌세포는 빛에 쉽게 노출되는 등부위와 상미병부, 맥락막-망막색소상피층 및 홍채에서 다량으로 분포하였다. 반면에 백색증 개체에서는 멜라닌세포가 등 부위와 등지느러미, 그리고 꼬리지느러미에서 아주 소량으로 분포하고 있었으며 눈의 맥락막-망막색소상피층 및 홍채에서는 색소결핍 현상이 뚜렷하게 관찰되었다.

• 한국치위생학회지
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• 제10권3호
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• pp.459-464
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• 2010

Objectives : The purpose of this study was to minimize cross infection that can take place within dental office, to make dental workers recognize importance of infection management, and to improve dental-care environment that is exposed to infection. Methods : It conducted the self-reported questionnaire survey on the practice of wearing PPE(personal protective equipment) from April 1, 2008 to May 30 targeting 180 dental workers who are working for dental offices where are located in Jeonnam region. Results : 1. As for research subjects' general characteristics, age was the largest in under 29 years old with 75.0%. It was surveyed to be large in over 5 years(56.1%) for working career, in a city(83.3%) for working region, and in having licence of dental hygienist(75.0%). 2. As a result of surveying the practice of wearing PPE, wearing mask given dental care was surveyed to have the highest practice level with 75.6%. Wearing protective glasses showed the lowest practice ratio with 23.3%. 3. As a result of surveying the difference in the practice of wearing PPE according to general characteristics, the difference according to the working region was surveyed to be the greatest. Conclusions : As the above result, the education of infection management for dental workers needs to be performed continuously even after curriculum of school. Even the in-service education on infection management needs to be vitalized. Also, the necessity was examined for always recognizing and practicing importance of infection by using a method of publishing newsletter via post to dental clinics where are located in rural area, with considering regional deviation.

• 한국패류학회지
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• 제28권3호
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• pp.277-291
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• 2012

Aquaculture is challenged by a number of constraints with future efforts towards sustainable production. Global climate change has a potential damage to the sustainability by changing environmental surroundings unfavorably. The damaging parameters identified are water temperature, sea level, surface physical energy, precipitation, solar radiation, ocean acidification, and so on. Of them, temperature, mostly temperature elevation, occupies significant concern among marine ecologists and aquaculturists. Ocean acidification particularly draws shellfish aquaculturists' attention as it alters the marine chemistry, shifting the equilibrium towards more dissolved CO2 and hydrogen ions ($H^+$) and thus influencing signaling pathways on shell formation, immune system, and other biological processes. Temperature elevation by climate change is of double-sidedness: it can be an opportunistic parameter besides being a generally known damaging parameter in aquaculture. It can provide better environments for faster and longer growth for aquaculture species. It is also somehow advantageous for alleviation of aquaculture expansion pressure in a given location by opening a gate for new species and aquaculture zone expansion northward in the northern hemisphere, otherwise unavailable due to temperature limit. But in the science of climate change, the ways of influence on aquaculture are complex and ambiguous, and hence are still hard to identify and quantify. At the same time considerable parts of our knowledge on climate change effects on aquaculture are from the estimates from data of fisheries and agriculture. The consequences may be different from what they really are, particularly in the temperature region. In reality, bivalves and tunicates hung or caged in the longline system are often exposed to temperatures higher than those they encounter in nature, locally driving the farmed shellfish into an upper tolerable temperature extreme. We review recent climate change and following environment changes which can be factors or potential factors affecting shellfish aquaculture production in the temperate region.

• Journal of Forest and Environmental Science
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• 제30권4호
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• pp.351-361
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• 2014

Leaf area ($A_0$) and leaf biomass ($M_0$) estimation are significant prerequisites to studying tree physiological processes and modeling in the forest ecosystem. The objective of this study was to develop allometric models for estimating $A_0$ and $M_0$ of Swietenia mahagoni L. from different tree parameters such as DBH and tree height of mahogany plantations in the northeastern region of Bangladesh. A total of 850 healthy and well formed trees were selected randomly for sampling in the five study sites. Then, twenty two models were developed based on different statistical criteria that propose reliable and accurate models for estimating the $A_0$ and $M_0$ using non-destructive measurements. The results exposed that model iv and xv were selected on a single predictor of DBH and showed more statistically accuracy than other models. The selected models were also validated with an additional test data set on the basis of linear regression and t-test for mean difference between observed and predicted values. After that, a comparison between the best logarithmic and non-linear allometric model shows that the non-linear model produces systematic biases and underestimates $A_0$ and $M_0$ for larger trees. As a result, it showed that the bias-corrected logarithmic model iv and xv can be used to help quantify forest structure and functions, particularly valuable in future research for estimating $A_0$ and $M_0$ of S. mahagoni in this region.

• Radiation Oncology Journal
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• 제2권1호
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• pp.149-153
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• 1984

Postoperative radiotherapy of breast cancer makes it possible to reduce loco-regional recurrence of breast cancer. The treatment technique, which can reduce the low-dose region at the junction and lung, is required. To produce proper dose distribution of internal mammary chain and chest wall, authors tried to find the method to expose $^{60}Co\;\gamma-ray$ on internal mammary region and 7MeV electron on chest wall. Exposure time of $^{60}Co\;\gamma$ and monitor unit of 9MeV were selected so that dose of $^{60}Co$ at 4cm depth was the same as that of 7Mev electron at $80\%$ dose depth. The position and direction of electron beam were changed for $^{60}Co$ beam: $0^{\circ},\;5^{\circ}$ for 0cm seperation; $0^{\circ},\;5^{\circ},\;10^{\circ}$ for 0.5cm seperation; $5^{\circ},\;10^{\circ},\;15^{\circ}$ for 1cm seperation. The results are as followings. 1. When the seperation of two fields was increased, dose on the axis of $^{60}Co$ beam was increased and dose at the junction region decreased while the volume of lung to be exposed to high dose and hot spot size were irregularly changed. 2. The dose distribution in the target volume of internal mammary and chest wall was most ideal when the seperation of two fields was $0\~0.5cm$ and the direction of electron beam was parallel to $^{60}Co$ beam.

• 한국전자파학회논문지
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• 제22권8호
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• pp.790-796
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• 2011

HEMP(High-Altitude Electromagnetic Pulse, 고 고도 전자기 펄스) 신호는 매우 큰 전계 값과 매우 빠른 상승시간 등으로 인해 그 영향 범위 안에 노출되어 있는 시스템은 심각한 손상을 입을 수도 있다. HEMP로부터 시스템을 적절하게 방호하기 위해서는 방호 설계 사양 도출 이전에 시스템의 개구면이나 케이블에 대한 전자기 결합 신호 해석이 먼저 수행되어야 한다. 본 논문에서는 RF 또는 비디오 신호 등을 전송하기 위해 사용되는 동축 케이블에 대한 HEMP 결합 신호를 해석하였고, 차폐선에 대한 HEMP 감소 효과를 확인하기 위해 단일 도선과 동축 케이블 내부 도선에 대한 결합 신호를 비교하였다. 동축 케이블은 차폐선의 외부 영역과 내부 영역으로 각각 분리되어 해석되었으며, 차폐선 표면 위의 전류 계산을 위해 동축 케이블 외부 영역에는 일반화 된 산란방정식을 적용하였고, 동축 케이블 내부 영역에는 Chain Matrix 알고리즘을 적용하였다. 본 논문의 해석 결과를 검증하기 위해 기존 논문의 결과 데이터와 비교하였고, 두 결과가 비슷한 경향을 나타내었다.