• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.190-199
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• 2008

To investigate hydrographic structure and characteristics of the tropical ocean in the eastern and the western Pacific, CTD(Conductivity-Temperature-Depth) data along $131^{\circ}W$ and $137^{\circ}-142^{\circ}E$ in July-August 2005 were analyzed. Sea surface temperature along $131.5^{\circ}W$ in summer is highest in the Equatorial Counter Current(ECC) because of the high-temperature water greater than $28^{\circ}C$ moving through the ECC from the western Pacific to the eastern Pacific in spring and summer. Based on the evidence of the presence of low salinity and high dissolved oxygen water in the North Equatorial Current(NEC), we suggested that the low salinity water moved from the Gulf of Panama to the east of Philippine along the North Equatorial Current(NEC). The South Equatorial Current(SEC) had the most saline water from surface to deep layer because the saline water from the Subtropical South Pacific Ocean moved to the north. The salinity minimum layer was observed at 500-1500 m depth along $131.5^{\circ}W$. The water mass with the salinity minimum layer in the north of $5^{\circ}N$ came from the North Pacific Intermediate Water(NPIW) and that in the south of $5^{\circ}N$ came from the Antarctic Intermediate Water(AAIW), which was more saline than the NPIW. Cyclonic cold eddy with a diameter of about 200km was found in $4-6^{\circ}N$. Sea surface temperature along $131.5^{\circ}W$ in the eastern Pacific was lower than along $137^{\circ}-142^{\circ}E$ in the western Pacific; on the other hand, sea surface salinity in the eastern Pacific was higher than in the western Pacific. Subsurface saline water from the Subtropical South Pacific Ocean was less saline in the eastern Pacific than in the western Pacific. Salinity and density(${\sigma}_{\theta}$) of the salinity minimum layer south of $14^{\circ}N$ was higher in the eastern Pacific than in the western Pacific.

• Perspectives in Nursing Science
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• v.7 no.1
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• pp.10-22
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• 2010

Purpose: Through a thorough examination of the CCSC (Community Comprehensive Support Center) system in Japan, this study suggests a scheme to provide community-based preventive health care services for the elderly in Korea. Methods: The study inquired into the applicability of the Japanese model by reviewing the data related to the CCSC project, aided by both in-depth interviews with staff in the field and consultations with specialists. Results: Rearrangement of the Visiting Health Management Project system is needed to manage the collective or individual visiting care management for frailty prevention of the elderly in communities. The delegated service system for preventive care in the community, including direct management by one of the public health centers, also needs to be reviewed and the application of stricter standards for the selection of the agency or corporation to run the delegated service is necessary. Long-Term Care Insurance, along with national and local grants, is to be considered as a financial resource for the community-based preventive health care model for the elderly. By making active use of education rooms at district offices, senior citizen centers in neighborhoods for the elderly with easy access can be created. The project needs to raise active supports from communities, develop programs which can be absorbed into particular local cultures, and promote the understanding of the preventive project in local communities. The preventive program should focus on first solving the problems of depression, seclusion, and lack of mobility of the elderly. Second, the program should instruct physical self-management for exercise-nutrition-dental maintenance, and third, the program should strengthen the cognitive abilities of the elderly. In addition, it is necessary to systematize and implement counter-plans of the family and community to protect the elderly who has mental and cognitive problems. Finally, by establishing a network of public health welfare resources based upon research on a community level, assessment and planning for the health of the elderly should be one with their family, and comprehensive consultation and recommendations should be provided to the family. Conclusion: Taking into consideration the experience Japan has had with respect to a similar project, it is appropriate to develop and implement a service system which would combine the Visiting Health Management Project system which has already been established and a preventive health care model for the elderly on a community level.

• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.143-150
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• 2017

Countercurrent oxidation process (COP) was developed and evaluated for treatment of highly concentrated PCB containing insulating oil. The PCB content in insulating oil taken from Haksanmetal company was found to be 1,512 ppm. The COP utilizes a self-sustained flame which propagates itself in a direction counter to the oxygen flow. The flame removes PCBs adsorbed in activated carbon and, at the same time, regenerates activated carbon. The flame temperature was determined from both mass loss of activated carbon and the relative ratio of CO and $CO_2$ exhausted during COP, and showed that its temperature lied in the range of $650-850^{\circ}C$. Removal efficiency of PCBs was achieved above 99.99% for 5% of insulating oil loaded activated carbon with 1 COP in weight ratio. Also, the same removal efficiency was acquired for 60% of insulating oil loaded activated carbon with three consecutive COP. In addition, specific surface area of activated carbon during COP was recovered to almost similar value of virgin activated carbon. It proved that the COP was much effective in removing high concentration of PCBs in insulating oil easily and affordably.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.5
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• pp.603-613
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• 2011

The collection of $PM_{10}$ and $PM_{2.5}$ samples was made at Gosan site of Jeju Island. Their ionic compositions of both inorganic and organic phases were then analyzed to examine their acidification and neutralization characteristics in atmospheric aerosols. The mass concentrations of $PM_{10}$ and $PM_{2.5}$ at Gosan site were $37.6{\pm}20.1$ and $22.9{\pm}14.3{\mu}g/m^3$, respectively, showing the content ratio of $PM_{2.5}$ to $PM_{10}$ as 61.0%. In the evaluation of ionic balance, the correlation coefficients (r) between the sums of cationic and anionic equivalent concentrations were excellent with 0.982 ($PM_{10}$) and 0.991 ($PM_{2.5}$). The concentration ratios of $PM_{2.5}/PM_{10}$ derived for nss-$SO_4^{2-}$, $NO_3^-$, and $NH_4^+$ were 0.94, 0.56, and 1.02, respectively, indicating the relative dominance of fine fractions. The acidifying capacity of inorganic anions ($SO_4^{2-}$ and $NO_3^-$) in $PM_{10}$ and $PM_{2.5}$ were 96.5% and 97.3%, while those of organic anions ($HCOO^-$ and $CH_3COO^-$) in each fraction were 2.9% and 2.0%, respectively. On the other hand, the neutralizing capacity of $PM_{10}$ and $PM_{2.5}$ by $NH_3$ were 72.8% and 82.3%, while their $CaCO_3$ counter parts were 22.5% and 13.3%, respectively.

• Journal of Life Science
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• v.19 no.10
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• pp.1368-1373
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• 2009

The purpose of this study was to assess the influence of waist size on the reliability and validity of pedometers to count steps in children and youth. The participants for this study were 20 children and youth, composed of 14 Hispanic and 6 Caucasian children. Ten children and youth had waist circumferences greater than the $85^{th}$ percentile (Body Mass Index (BMI)=$28.91\pm3.07$), and 10 children and youth had waist circumferences smaller than the $50^{th}$ percentile (BMI=$18.05\pm1.55$). To examine pedometer reliability, each child completed 3 ascent and descent trials up a set of 15 stairs while wearing a Yamax SW-701 pedometer. The main effect of trials was not statistically significant for the stair ascent trials F (2, 36)=2.575 or for the descent trials F (2, 36)=0.235. The trial by group interaction was also not statistically significant. To examine the influence of waist circumference on the validity of the pedometer in counting walking steps at a self-selected walking pace, the children and youth in the two groups completed a 400-m course. The main effect on the groups was statistically significant, F (1, 18)=7.489. The main effect of counting techniques was not statistically significant, F (1, 18)=2.983 (hand-counted vs. pedometer counted). Overall, the trial and trial by group interaction comparisons for the 400-m walk were not statistically significant, suggesting that the pedometer was equally valid as a tool for assessing walking steps in high waist circumference (HWC) and low waist circumference (LWC) in children and youth.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.225-236
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• 2016

Objectives: Nanomaterials have been used in various fields. As use of nanoproducts is increasing, workers dealing with nanomaterials are also gradually increasing. Exposure assessments for nanomaterials have been carried out for protection of worker's health in workplace. Exposure studies were mainly focused on manufacturing processes, but these studies on after-treatment processes such as refinement, weighing, and packing were insufficient. So, we investigated exposure characteristics of particles during after-treatment processes of $Al_2O_3$ fibers and Ni powders. Methods: Mass-production of Ni powder process was carried out in enclosed capture-type canopy hood. In a developing stage, $Al_2O_3$ was handled with a local ventilation unit. Exposure characteristics of particles were investigated for $Al_2O_3$ fiber and Ni powder processes during the periods of 10:00 to 16:00, 20 May 2014 and 13:00 to 16:00, 21 May 2014, respectively. Three real-time aerosol instruments were utilized in exposure assessment. A scanning mobility particle sizer(SMPS, nanoscan, model 3910, TSI) and an optical particle counter(OPC, portable aerosol spectrometer, model 1.109, Grimm) were used to determine the particle size distribution in the size range of 10-420 nm and $0.25-32{\mu}m$, respectively. In addition, a nanoparticle aerosol monitor(NAM, model 9000, TSI) was used to measure lung-deposited nanoparticle surface area. Membrane filters(isopore membrane filter, pore size of 100 nm) were also used for air sampling for the FE-SEM(model S-5000H, Hitachi) analysis using a personal sampling pump(model GilAir Plus by 2.5 L/min, Gilian). Conclusions: For Ni powder after-treatment process, only 27% increase in particle concentration was found during the process. However, for $Al_2O_3$ fiber after-treatment process, significant exposure(1.56-3.34 times) was observed during the process.

• Solar Energy
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• v.15 no.3
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• pp.3-14
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• 1995

The Direct Contact heat Exchanger(DCHX) has been widely studied in the chemical industry for many years due to its inherent simplicity as a counter-current divice for heat and mass transfer. In many solar systems, the DCHX unit can be combined with the thermal storage unit, or alternatively, it can be used separately from the storage unit, much like an external(to storage) closed heat exchanger system. In the present work, the spray column type of direct contact heat exchangers are studied extensively to harness the solar energy for hot water and spaced heating. Some of the major considerations that are involved in the design of heat exchangers in this study are that : working fluid is a hydrocaabon(such as Texaterm) or water which is either lighter or heavier than storage medium. The experimental data have revealed some interesting characteristics concerning the application of DCHXs for solar energy utilization. These experiments are carried out in the line of solar heating system, major results are as follows : 1) the flow and aspect of working fluid drop for maxium heat transfer 2) efficiency and volumetric heat transfer coefficient of D.C.H.X with a heavier working fluid are higher than those of D.C.H.X with a lighter working fluid.

• Particle and aerosol research
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• v.16 no.4
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• pp.131-140
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• 2020

Air pollutants emitted from chimneys of coal-fired power plants are considered to be a major source of fine particulate matter in the atmosphere. In order to manage fine particle in the chimney of a coal-fired power plant, it is necessary to know the concentration of fine particle emitted in real time, but the current system is difficult. In this study, a real-time measurement system for chimney fine particle was developed, and measurements were performed on six coal-fired power plants. Through the measurements, the mass concentration distribution according to the particle size could be secured. All six chimneys showed bimodal distribution, and the count median diameters of each mode were 0.5 and 1.1 ㎛. In addition, it was compared with the gravimetric measurement method, and it was determined that the relative accuracy for PM10 was within 20%, and the value measured using the developed measuring instrument was reliable. Finally, three power plants were continuously measured for one month, and as a result of comparing the concentration of PM10 according to the amount of power generation, it was confirmed that the PM10 discharged from the chimney increased in the form of an exponential function according to the amount of power generation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.85-97
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• 2024

Objectives: This study was intended to investigate the revision status of the occupational exposure standards for aluminum at home and abroad; to investigate worker exposure at domestic aluminum manufacturing and handling workplaces; to conduct social and economic evaluation for the revision of domestic aluminum exposure limits. Methods: We investigated the current status of occupational exposure limits for aluminum at home and abroad, and analyzed supporting data. An exposure survey was conducted targeting domestic aluminum manufacturing and handling workplaces. Based on these, revised aluminum occupational exposure limits were proposed. Results: The major aluminum exposure limits at home and abroad show a notable difference. The toxicity of aluminum, which was revealed through animal experiments and epidemiological investigations. The average concentration of aluminum in the air at 12 workplaces was 0.016 mg/m³, and the maximum was 0.0776 mg/m³. When total dust and respiratory dust were measured side by side and simultaneously for the same process, 12.1% of the total mass concentration of aluminum dust was respiratory dust. As a result of measuring and comparing the size distribution of dust with an optical particle counter in real time, 48.1% of the total dust in the form of welding fume and pyro-powder was respiratory dust. Based on the literature review and workplace survey, three proposals for changing the aluminum exposure limit were proposed. Proposal (1): For all types, 10 mg/m³ is unified as the exposure limit except for soluble salts and alkyls. Proposal (2): 1(R) mg/m³ as the exposure limit for all forms except soluble salts and alkyl. Proposal (3): 1(R) mg/m³ for pyro-powder and welding fume, and 10 mg/m³ for metal dust, aluminum oxide, and insoluble compounds as exposure standards. A pyro-powder was defined as dry aluminum powder of 200 mesh size (74 ㎛) or smaller (larger size classified as metal dust). Reason for setting: In the workplace survey, the ratio of respiratory dust to total dust was analyzed to be about 1:10, so it was judged that the domestic standard and the ACGIH standard were compatible. Conclusions: In all scenarios according to the revision of the exposure standard, the B/C ratio was greater than 1 or only benefits existed, so it was evaluated as sufficiently reasonable as a result of the socio-economic evaluation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.3
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• pp.117-123
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• 2006

The water quality before and after a typhoon was investigated as a part of a study on the increase of organic matter and on the fundamental measures to counter chemical oxygen demand (COD) in the eutrophic Soho coastal seawaters of Gamak Bay. The dissolved oxygen (DO) saturations were <54% when water column was stratified. The DO saturation was similar at surface and in the bottom layer after a typhoon $(78\sim88%)$, and a very high DO saturation (234%) was observed in the surface water after mass phytoplankton growth. The highest values of $NH_4-N,\;NO_3-N,\;PO_4-P$, and $SiO_2-Si$ were 18.22, 38.90, 1.58, and $52.10{\mu}M$, respectively, when freshwater entered after heavy rainfall events. In addition, high concentrations of $NH_4-N,\;PO_4-P$, and $SiO_2-Si$ were detected with low DO saturations in bottom water (>5m). A maximum chlorophyll (Chl.) concentration of $311.0{\mu}gl^{-1}$ was observed after typhoon, when a high-density Scrippsiella trochoidea red tide occurred with cell density of 42,000 cells $ml^{-1}$. The algal growth potential (AGP) was high after the typhoon. Nitrogen was always a limiting nutrient for phytoplankton growth. The highest COD level was $10.55mgl^{-1}$, and the main reason of the variation in COD was likely to be phytoplankton growth $(r^2=0.612,\;p=0.000)$. Organic matter, which entered the water column when the typhoon stirred the sediments, seems to have little effects on COD increase.