• Progress in Medical Physics
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• v.23 no.2
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• pp.71-80
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• 2012

In order to verify exact dose distributions in the state-of-the-art radiation techniques, a newly designed three-dimensional dosimeter and technique has been took strongly into consideration. The main purpose of our study is to verify the optimized parameters of polymer gel as a real volumetric dosimeter in terms of the various study of MRI. We prepared a gel dosimeter by combing 8% of gelatin, 8% of MAA, and 10 mM of THPC. We used a Co-60 gamma-ray teletherapy unit and delivered doses of 0, 2, 4, 6, 8, 10, 12, and 14 Gy to each polymer gel with a solid phantom. We used a fast spin-echo pulse to acquire the characterized T2 time of MRI. The signal noise ratio (SNR) of the head & neck coil was a relatively lower sensitivity than the body coil; therefore the dose uncertainty of head & neck coil would be lower than body coil's. But the dose uncertainty and resolution of the head & neck coil were superior to the body coil in this study. The TR time between 1,500 ms and 2,000 ms showed no significant difference in the dose resolution, but TR of 1,500 ms showed less dose uncertainty. For the slice thickness of 2.5 mm, less dose uncertainty of TE times was at 4 Gy, as well, it was the lowest result over 4 Gy at TE of 12 ms. The dose uncertainty was not critical up to 6 Gy, but the best dose resolution was obtained at 20 ms up to 8 Gy. The dose resolution shows the lowest value was over 20 ms and was an excellent result in the number of excitation (NEX) of three. The NEX of two was the highest dose resolution. We concluded that the better result of slice thickness versus NEX was related to the NEX increment and thin slice thickness.

• Tuberculosis and Respiratory Diseases
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• v.61 no.1
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• pp.46-53
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• 2006

Background: Intra-abdominal hypertension (IAH) is defined as the presence of either an intra-abdominal pressure (IAP) ${\geq}12mmHg$ or an abdominal perfusion pressure (APP = mean arterial pressure - IAP) ${\leq}60mmHg$. Abdominal compartment syndrome (ACS) is defined as the presence of an IAP ${\geq}20mmHg$ together with organ failure. The purpose of this study was to investigate the prevalence of IAH and ACS on the day of admission and the effects of these maladies on the prognosis of critically ill patients in the ICU. Methods: At the day of admission to the ICU, the IAP was recorded by measuring the intravesicular pressure via a Foley catheter. The APACHE II and III scores were checked and SAPS II was also scored during the days the patients were in the ICU. The primary end point was the prevalence of IAH and ACS at the day of admission and the correlation between them with the 28-days mortality rate. The measurement of IAP continued until the 7th day or the day when the patient was transferred to the general ward before 7th day, unless the patient died or a Foley catheter was removed before 7th day. Patients were observed until death or the 28th day. Results: A total of 111 patients were enrolled. At the day of admission, the prevalence of IAH and ACS were 47.7% and 15.3%, respectively and the mean IAP was $15.1{\pm}8.5mmHg$. The rates of IAH for the survivor and the non-survivor groups were 56.5% and 71.4%, respectively, and these were not significantly different (p=0.593). Yet the rates of ACS between these two groups were significantly different (4/62, 6.5% vs. 13/49, 26.5%; Odds Ratio = 5.24, 95% CI = 1.58-17.30, p=0.004). Conclusion: In the present study, the prevalence of IAH was 47.7% and the prevalence of ACS was 15.3% on the day of admission. ACS was associated with a poor outcome for the critically ill patients in the ICU.

• Journal of the Korean Society of Child Welfare
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• no.36
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• pp.165-196
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• 2011

With the increasing concerns of victimization of school violence, this paper is intended to present a pioneering study on the victims' conscientization which may result from their own experience of school violence by peers. The predominant concern of the study consists in: (1) the direct effects of individuals' perception toward violence in general, non-assertiveness, school violence experience by peers, and prosocial behavioral tendency on the individual conscientization of school violence problems; (2) the indirect effects of both individual prosocial behavioral tendency and perceptions toward violence through non-assertiveness on individual conscientization of school violence problems;(3) the sexual differences of the five latent variables(perceptions toward violence in general, non-assertiveness, prosocial behavioral tendency, school violence experience by peers, and conscientization of school violence problems; (4) the sexual differences of both direct and indirect correlates on conscientization of school violence problems. Research is based on a survey conducted with 526 adolescents (268 males and 258 females) from 16 middle schools located in different districts of the city of Pohang. In order to address the research questions, structural equation models on adolescents' conscientization of school violence are explored. A variety of tests are conducted (configural invariance, metric invariance and structural invariance, intercept invariance, critical ratio for difference test, multi-group analysis, latent mean analysis including Cohen's effect test). The major findings of the study support the significance of both direct effects and indirect effects of the four latent factors(perceptions of violence in general, non-assertiveness, prosocial behavioral tendency, school violence experience by peers). The individual prosocial behavioral tendency has a positive mediating effect on the enhancement of individual conscientization toward school violence problems. However, we fail to find the direct positive effect of individual violence experience on the conscientization of school violence problems. In conclusion, a range of practical implications for social workers and other related professionals who are engaged in helping out the adolescents with school violence by peers are suggested based on the study findings.

• Resources Recycling
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• v.28 no.5
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• pp.60-67
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• 2019

A valuable metal recovery from waste resources such as spent rechargeable secondary batteries is of critical issues because of a sharp increase in the amount of waste resources. In this context, it is necessary to research not only recycling waste lithium-ion batteries (LIBs), but also reusing valuable metals (e.g., Li, Co, Ni, Mn etc.) recovered from waste LIBs. In particular, the lithium hydroxide ($LiOH{\cdot}xH_2O$), which is of precursors that can be prepared by the recovery of Li in waste LIBs, can be reused as a catalyst, a carbon dioxide absorbent, and again as a precursor for cathode materials of LIB. However, most studies of recycling the waste LIBs have been focused on the preparation of lithium carbonate with a recovery of Li. Herein, we show the preparation of high purity lithium hydroxide powder along with the precipitation process, and the systematic study to find an optimum condition is also carried out. The lithium carbonate, which is recovered from waste LIBs, was used as starting materials for synthesis of lithium hydroxide. The optimum precipitation conditions for the preparation of LiOH were found as follows: based on stirring, reaction temperature $90^{\circ}C$, reaction time 3 hr, precursor ratio 1:1. To synthesize uniform and high purity lithium hydroxide, 2-step precipitation process was additionally performed, and consequently, high purity $LiOH{\cdot}xH_2O$ powder was obtained.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.734-744
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• 2011

A soil stabilization method is an effective and practical remediation alternative for arsenic (As) and heavy metal contaminated farmland soils nearby abandoned metal mine in Korea. This method is a technique whereby amendments are incorporated and mixed with a contaminated soil. Toxic metal bind to the amendments, which reduce their mobility in soil, so the successful stabilization of multi-element contaminated soil depends on the combination of critical elements in the soil and the type of amendments. The objective of this study is to investigate the treatment effects and applicability of limestone (LS) and steel refining slag (SRS) as the amendment for farmland soil contaminated with As and heavy metals, and a lab-column test was conducted for achieving this purpose. The result showed that soil treated with LS and SRS maintained pH buffer capacity and, as a result, the heavy metal leaching concentration was quite low below the water quality standard compared to untreated soil which leachate exceeding the water quality standard was observed, however, the arsenic concentration rather increased with increasing mixture ratio of SRS. This was believed to be related to phosphorus (P) contained in SRS, and dominancy in the competitive adsorption relation between As and P binding strongly to iron might be different according to soil characteristic. We suggested that LS is a effective amendment for reducing heavy metals in soil, and SRS should be used after investigating its applicability based on the adsorption selectivity of arsenic and phosphorus in selected soil.

• Food Engineering Progress
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• v.15 no.4
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• pp.404-412
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• 2011

The purpose of this study is to prepare extruded rice flours suitable for baking rice cookies. The extruded rice flours were prepared at 100 and 130$^{\circ}C$ temperature and 25 and 27% moisture content in a co-rotating twin screw extruder. The rice extrudates were dried at 100$^{\circ}C$ for 18 hr and subsequently ground into the fine flour. Characteristics of the extruded rice flours were examined by rapid visco analysis, hydration property analysis, differential scanning calorimetry (DSC), and in vitro digestion test. Water absorption, solubility, and swelling power of all extruded rice flours were higher than those of native rice flour. DSC analysis showed that native rice flour had a peak at about 65$^{\circ}C$ while all extruded rice flours did not show any peaks since they were already gelatinized during the extrusion proess. Viscosity of the extruded rice flours decreased with increasing temperature and lowering moisture content in the extrusion proess. The extruded rice flours prepared at 130$^{\circ}C$ exhibited lower viscosity than those prepared at 100$^{\circ}C$. The operating temperature of the extrusion proess was critical for the starch digestion in vitro. The extruded rice flours prepared at 130$^{\circ}C$ showed a rapid decrease in digestible starch content while an increased level of slowly digestible starch content was observed compared to those treated at 100$^{\circ}C$ in the extruder. Cookies were prepared with a mixture of wheat flour and extruded rice flours at the ratio of 7 to 3. The cookies made with the extruded rice flours had lower spread factor and darker yellow color than those prepared with wheat flour only. Hardness of the extruded rice flour-added cookies was similar to that of the wheat flour cookie whereas their overall acceptance was better. Therefore the rice cookies partially supplemented with extruded rice flours may have a potential as early childhood foods which require soft texture and allergy reduction.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.651-662
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• 2022

The electrochemical impedance spectroscopy(EIS) method was used to evaluate the concrete deterioration process related to chloride-induced steel corrosion with various corrosion levels(initiation, rust propagation and acceleration periods). The impressed current technique, with four total current levels of 0C, 13C, 65C and 130C, was used to accelerate steel corrosion in concrete cylinder samples with w/c ratio of 0.4, 0.5, and 0.6, immersed in a 0.5M NaCl solution. A series of EIS measurements was performed to monitor concrete deterioration during the accelerated corrosion test in this study. Some critical parameters of the equivalent circuit were obtained through the EIS analysis. It was observed that the charge transfer resistance(R_c) dropped sharply as the impressed current increased from 0C to 13C, indicating a value of approximately 10kΩcm². However, the sensitivity of R_c significantly decreased when the impressed current was further increased from 13C to 130C after corrosion of steel had been initiated. Meanwhile, the double-layer capacitance value(C_dl) linearly increased from 50×10^-6μF/cm² to 250×10^-6μF/cm² as the impressed current in creased from 0C to 130C. The results in this study showed that monitoring C_dl is an effective measurement parameter for evaluating the progress of internal concrete damages(de-bonding between steel and concrete, micro-cracks, and surface-breaking cracks) induced by steel corrosion. The findings of this study provide a fundamental basis for developing an embedded sensor and signal interpretation method for monitoring concrete deterioration due to steel corrosion at various corrosion levels.

• Journal of fish pathology
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• v.35 no.1
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• pp.1-25
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• 2022

The aquaculture industry has developed rapidly over the last three decades and is an important industry that supplies over 15% of humans' animal protein intake; therefore, there is a need to increase production to meet the continuous demand. The fish cage farms on the southern coast (Kyengsangnam-do and Jeollanam-do) of Korea are critical resources in aquaculture because they account for approximately 90% of the national total fish cage farms by water area ratio. However, the current aquaculture environment is being gradually affected by climate change, which is a global issue, and its effects are expected to intensify in the future. Therefore, it is urgently imperative to accurately evaluate the effects of climate change on South Korean aquaculture industries and to develop social and national strategies to minimize damage to the fishing industry. The damage to fish farmed in cage farms on the southern coast is increasing annually and the leading causes are high and low water temperature and red tides, which are directly or indirectly related to climate change. At present, global warming can provide opportunities for aquaculture industrialization of fish or other novel species, with economic implications. However, despite such opportunities, the influx of new species can also cause problems such as ecological disturbances, increase in the reproduction frequency of microalgae such as red tide, increase in disease incidence, and occurrence and periods of high water temperatures in summer. The scale of farmed fish mortality is increasing due to the complex effects of these factors. Increased damages due to fish mortality not only have severe economic impacts on the aquaculture industry, but the social costs of responding to the damage and follow-up measures also increase. various active responses can reduce the mortality damage in fish farms such as improving the management skills in aquaculture, improved species breeding, efficient food management, disease prevention, proactive responses, and system-wide improvements. This review article analyzes the large-scale mortality cases occurring in fish cage farms on the southern coast of Korea and proposes measures to mitigate mortality and enhance responses to such scenarios.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.283-298
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• 2022

In this study, we investigated the mineral geochemistry of the albite-spodumene pegmatite, associated exogreisen, and wall rock from the Boam Li deposit, Wangpiri, Uljin, Gyeongsangbuk-do, South Korea. The paragenesis of the Boam Li deposit consists of two stages; the magmatic and endogreisen stages. In the magmatic stage, pegmatite dikes mainly composed of spodumene, albite, quartz, and K-feldspar intruded into the Janggun limestone formation. In the following endogreisen stage, the secondary fine-grained albite along with muscovite, apatite, beryl, CGM(columbite group mineral), microlite, and cassiterite were precipitated and partly replaced the magmatic stage minerals. Exogreisen composed of tourmaline, quartz, and muscovite develops along the contact between the pegmatite dike and wall rock. The Cs contents of beryl and muscovite and Ta/(Nb+Ta) ratio of CGM are higher in the endogreisen stage than the magmatic stage, suggesting the involvement of the more evolved melts in the greisenization than in the magmatic stage. Florine-rich and Cl-poor apatite infer that the parental magma is likely derived from metasedimentary rock (S-type granite). P₂O₅ contents of albite in the endogreisen stage are below the detection limit of EDS while those of albite in the magmatic stage are 0.28 wt.% on average. The lower P₂O₅ contents of the former albite can be attributed to apatite and microlite precipitation during the endogreisen stage. Calcium introduced from the adjacent Janggun formation may have induced apatite crystallization. The interaction between the pegmatite and Janggun limestone is consistent with the gradual increase in Ca and other divalent cations and decrease in Al from the core to the rim of tourmaline in the exogreisen.

• Korean Journal of Culture and Social Issue
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• v.18 no.4
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• pp.435-462
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• 2012

The predominant concern of the study centers on: (1) the direct effects of the job satisfaction, social support and hope on the individual's quality of life; (2) the direct effect of hope alone on the individual's quality life; (3) the mediating effect of the hope between the job satisfaction/social support and life quality; (4) the moderating effect of the worker's legal status(legal labors Vs. illegal labors) on each causal relationship. Research is based on a survey conducted with 453 Mongolian immigrant workers(333 legal workers, 120 illegal workers) from 10 cities including Seoul. In order for respondents to address research questions, structural equation models are explored. A variety of tests are conducted(metric invariance test, critical ratio for difference test, multi-group analysis, bias-corrected boot-strapping, latent mean analysis including Cohen's effect test). The noticeable findings are as follow: First, both job satisfaction and social support have a positive influence respectively on the individual's hope and the individual's quality of life. Second, we found a partial mediating effect of hope between both job satisfaction/social support and the individual's life quality. Third, we failed to find a moderating effect of the workers' legal status on each causal relationship. Finally, there is no significant difference of the latent means of each latent variable -job satisfaction, social support, hope, and life quality - between the legal group and the illegal group, except the latent mean of workers' quality of life. A range of practical and political implications are discussed based on the study's findings.