• Journal of Korean Society for Atmospheric Environment
• /
• v.14 no.1
• /
• pp.43-62
• /
• 1998

This study was carried out to investigate the influence of different sampling methods on the measured concentrations of polycyclic aromatic hydrocarbons (PAH) both in the vapor and particulate phases, and to evaluate the effects of ambient temperature and sampling duration on the losses of PAH associated with particle samples due to volatilization. The experimental protocol of this study is consisted of two parts. The first part is related to the comparison of PAH concentrations measured by 4 different sampling systems, each of which involves different sampling principles for comparison purposes, including a medium-volume sampler with XAD-2 adsorbent, a high-volume sampler with polyurethane foam (PUF), two identical low-volume samplers: one with XAD-2 and the other with PUF, respectively. The second part of this study is to quantitatively estimate the losses of particulate PAH samples by volatilization during sampling, using two identical low-volume samplers: one was used for changing the filters every 3 hrs, 6 hrs, 12 hrs, and 24 hrs sampling, while the other was maintained for continuous 48 hours sampling without changing the filter. The concentrations of volatile PAH including 2-3 rings appeared to be significantly affected by the type of adsorbent. Measured levels of these lower-molecular weight PAH by XAD-2 adsorbent were much higher than those by PUF for both high-volume and low-volume sampling. PUF was found to give rise to unknown components that interfered with the PAH analysis, even after extensive clean-up. In addition, the retention efficiency of PUF for lower molecular weight PAH was subject to a large variation, being significantly influenced by sampling conditions such as ambient temperature. However, the effect of sampling methods with different adsorbents on the measured levels of semi-volatile compounds including 4 rings PAH such as fluoranthene, pyrene, BaA and chrysene, was not so much significant as more volatile PAH compounds. It was also clear from this study that volatilization losses of the semi-volatile PAH collected on the filters were inevitably occurred during prolonged sampling, and hence the results obtained from conventional sampling methods may not be expected to yield an accurate distribution of PAH between the vapor and particulate phases.

• Asian-Australasian Journal of Animal Sciences
• /
• v.29 no.6
• /
• pp.768-774
• /
• 2016

The present study investigated the impact of parity 1 gilt body weight during late gestation (d 109) on subsequent reproductive performance of sows and performance of suckling pigs. A total of 2,404 farrowing records over 6 parities were divided into six groups on the basis of body weight (190, 200, 210, 220, 230, and 240 kg) at d 109 of gestation of 585 gilts. Significant effects (p<0.05) of body weight on sow retention rate was noticed, with the 210 kg group having the lowest culling rate and highest total number of piglets born alive over the 6 parities. With increase of body weight, a linear increase (p<0.05) in losses of body weight and backfat during the lactation period of parity 1 and a linear decrease (p<0.05) in backfat loss for parities 4 and 6 were found. Compared with light sows, heavy sows had higher (p<0.05) litter weight at birth for parities 1 and 2 and at weaning in parity 1. Sow weaning-to-estrus interval of sows was not influenced (p>0.05) by body weight. In conclusion, maintaining optimal body weight during gestation would be beneficial to sows and suckling piglets.

• The Korean Journal of Ecology
• /
• v.26 no.4
• /
• pp.203-208
• /
• 2003

Losses in the dry weight of leaf litter from six tree species were studied during 16 months on the forest floor in temperate deciduous forest of Mt. Cheonma in the vicinity of Seoul in Korea by using litter bag method. The decomposition rate of each leaf litter varies with each species. After 16 months elapsed, the leaf litter of Acer pseudo-sieboidianum showed the highest decomposition constant (0.82) as Olson´s decomposition constant, while that of Pinus densiflora showed the lowest decomposition constant (0.33). The decomposition constant of Quercus mongolica, Q. serrata, Betula ermani and Carpinus laxiflora showed 0.43, 0.37, 0.66 and 0.75, respectively. The decomposition constant of leaf litter was considered with temperature and precipitation which accumulated daily during each term of litter bag collection. The decomposition constant of leaf litter showed closely positive correlation with daily accumulative temperature and precipitation. The relationships between decomposition constant and the daily accumulative temperature and precipitation at each period of litter bag collection were analyzed through multi-regression analysis. The correlation coefficients as a result of multi-regression analysis in Q. mongolica, Q. serrata, P densiflora, B. ermani, C. laxiflorais and A. pseudo-sieboldianum were 0.83, 0.81, 0.69, 0.77, 0.77 and 0.62, respectively. The precipitation showed higher effect, about 10 times, on the leaf litter decomposition than the daily accumulative temperature.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.19 no.1
• /
• pp.60-68
• /
• 2013

Purpose: This research was conducted to compare the effect of a wellness program on knowledge of obesity and weight loss in women schizophrenia inpatients. Methods: A nonequivalent control group pretest-posttest design was used for this study. A total of 44 patients with schizophrenia were randomly divided into an experimental group (22) and a control group (22) in a 12-week multimodal weight control program. For 6 weeks, the experimental group received approximately an hour of teaching on obesity interventions and for another 6 weeks one hour of teaching on exercise and weight control interventions while the control group received the usual care. The outcome variables were measured before and after the program. Data was analyzed with the ${\chi}^2$-test and t-test using PASW Statistics 18. Results: For those who completed the weight control program, there was a mean weight loss of 1.37kg by the end of the intervention. The experimental group showed significant improvement in knowledge of obesity and weight loss. Conclusion: The wellness program was effective in reducing the weight of women schizophrenia patients as well as being effective in increasing knowledge of obesity. Therefore, nurses must consistently educate women schizophrenia inpatients about health care and knowledge of obesity.

• Journal of Power Electronics
• /
• v.17 no.1
• /
• pp.200-211
• /
• 2017

Conventional boost-full-bridge and boost-hybrid-bridge two-stage inverters are widely applied in order to adapt to the wide dc input voltage range of photovoltaic arrays. However, the efficiency of the conventional topology is not fully optimized because additional switching losses are generated in the voltage conversion so that the input voltage rises and then falls. Moreover, the electrolytic capacitors in a dc-link lead to a larger volume combined with increases in both weight and cost. This paper proposes a higher efficiency inverter with time-sharing synchronous modulation. The energy transmission paths, wheeling branches and switching losses for the high-frequency switches are optimized so that the overall efficiency is greatly improved. In this paper, a contrastive analysis of the component losses for the conventional and proposed inverter topologies is carried out in MATLAB. Finally, the high-efficiency under different switching frequencies and different input voltages is verified by a 3 kW prototype.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.4
• /
• pp.167-173
• /
• 1999

The use of high-Tc superconducting synchronous motor in power machinery has many advantages such as reduced power dissipation, size and weight. This paper presents the ac loss simulation in the rotor having an high-Tc superconducting field winding using Ag sheathed Bi-2223. The analysis was conducted with an equivalent model of the high-Tc superconducting motor with flux damper under transition condition during which the load varies from 0 watt to 250watts and from 250watts to 500watts. The simulation results show that the transient state lasts for about 3 seconds, and the ac losses decreased exponentially from the initial value above 20mW.

• Korean Journal of Materials Research
• /
• v.32 no.5
• /
• pp.280-286
• /
• 2022

Corrosion is a natural, inevitable process, and is one of the world's most serious problems. Losses incurred due to corrosion are extremely expensive for society. Several technological strategies have been explored and implemented to address these losses. The use of inhibitors to prevent corrosion is a common and efficient method to reduce corrosion losses. This review covers Al and Al-composite corrosion inhibitors in chloride-containing solutions, because of their popularity in a broad array of industrial applications. A vast number of studies in the literature detail the common tendency of Al and Al-composites with reinforcements to deteriorate. Accordingly, it is worthwhile to employ inhibitors to protect them, as discussed in the present work. The emphasis is on selecting the smartest corrosion inhibitor and evaluating its performance. According to the study, the most commonly used corrosion inhibitors are 1,4-naphthoquinone (NQ), 1,5-naphthalene diol, 3-amino-1,2,4-triazole-5-thiol (ATAT), ammonium tetrathiotungstate, clotrimazole, amoxicillin, antimicrobial and antifungal drugs. Electrochemical impedance spectroscopy (EIS), potentiodynamic (PDP), and weight loss were among the most commonly used modern electrochemical technologies to test inhibitors' efficacy under environmental conditions.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.345-347
• /
• 1994

It is importent to have the switching frequency of power supplies increase in order to reduce their size and weight. But according to increasing the switching frequency, there are several defacts - that is switching losses, high voltage/current stresses and conduction losses and so on. That's why soft switching method was proposed. This paper presents the simulation and analysis of the new proposed Full bridge Zero-Voltage-Transition PWM DC-DC converter for developing that unit. This circuit doesen't increase the voltage and current stresses of main MOSFET switches. Voltage type quasi-resorent method is applied and expected high effenciency. Switching frequency is 100KHz and main switches are MOSFET.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.10
• /
• pp.511-520
• /
• 2006

Recently, more attention has been paid to the development of high-speed permanent magnet (PM) synchronous motors, since they are conductive to high efficiency, high power density, small size, and low weight. In high-speed PM machines, core loss and windage loss form a larger proportion of the total losses than usual in conventional mid- or low speed machines. This article deals with the analysis on the core loss and windage loss in PM synchronous motor for high-speed application. Using the data information from a manufacturer and non-linear curve fitting, this paper investigates the magnetic behavior and its core losses in the stator core using the electrical steels. And, the windage loss is calculated according to the variation of the rotational speed, motor inner pressure and temperature.

• Journal of Nutrition and Health
• /
• v.21 no.5
• /
• pp.317-323
• /
• 1988

Mean daily excretion of Ca, P, and Fe were measured in 49 healthy young Koreans(23 males and 26 females) form urine and feces samples cellected for three days. Dietary intakes of the subjects during the study periods were calculated from intake records. Main results of the study are as following: 1) Mean daily urinary, fecal, and total Ca excretions were 162$\pm$20mg, 346$\pm$39mg, and 508$\pm$50mg, respectively in males and 154$\pm$16mg, 262$\pm$26mg, and 416$\pm$24mg, respectively in females. The mean values of the two groups were not significantly different. 2) Mean daily urinary, fecal, and total P excretions were 751$\pm$45mg, 384$\pm$26mg and 1135$\pm$56mg, respectively in males and 552$\pm$29mg, 335$\pm$34mg and 894$\pm$50mg, respectively in females. Urinary and total P excretion in males were significantly higher than females(p<0.01), but such differences disappeared when the excretions were calculated per kg body weight. 3) mean daily fecal Fe excretions were 12.8$\pm$0.9mg in males and 10.1$\pm$0.8mg in females. The mean value in males was significantly higher than that in females(p<0.05) but when calculated per kg body weight, both groups excreted 0.2mg/kg body weight. 4) Mean daily intake levels of the minerals estimated from three day food intake records were Ca 543mg, P 1136mg, and Fe 14.3mg in males and Ca 533mg, P 869mg, Fe 10.8mg in females. These intake levels seem to be sufficient to supply the daily losses of the study subjects except P in females. However, the problem of estimating dietary intake levels by food intake record should be recognized. Especially females in the study are in menstration age and their Fe losses in the menstration (estimated to be 0.5mg of available Fe per day) should be also supplied in the diet.