• Journal of Environmental Science International
• /
• v.12 no.12
• /
• pp.1235-1243
• /
• 2003

Under controlled conditions in an environmental chamber, 24 experiments were performed to compare the ability of a Variable-Air-Volume/Bypass Filtration System(VAV/BPFS) to remove indoor pollutants and to conserve energy with the ability of conventional Variable Air Volume(VAV) system. The specific conclusions of this paper were; first, the VAV/BPFS was more efficient than the VAV system in removing particulate matter, TVOC, and target VOCs. The total effective removal rate of PM for the VAV/BPFS was two times as high as that of the VAV system. The total effective removal rate of TVOC for the VAV/BPFS was 20 percent higher than that of the VAV system. Also each target VOC concentration was reduced by using the VAV/BPFS. Second, clean air delivery rate was increased by using VAV/BPFS due to additional filtration rate. Otherwise, the VAV/BPFS decreased outdoor supply air rate above 25 percent relative to the rate of VAV system. Third, total energy consumption by the VAV/BPFS was lower than that of the VAV system during the period with indoor thermal load, occupied time. The energy saving of the VAV/BPFS ranged from 11 to 16 percent. The VAV/BPFS improves indoor air quality more efficiently than the VAV system, and it reduced energy consumption. Retrofitting the VAV system with the VAV/BPFS was easy The use of VAV/BPFS is, therefore, recommended far buildings with VAV system as well as for buildings at designing stage.

• Korean Journal of Radiology
• /
• v.25 no.2
• /
• pp.199-209
• /
• 2024

Objective: This study aimed to compare therapeutic efficacy and technical outcomes between adjustable electrode (AE) and conventional fixed electrode (FE) for radiofrequency ablation (RFA) of benign thyroid nodules. Materials and Methods: Between 2013 and 2021, RFA was performed on histologically proven benign thyroid nodules. For the AE method, AE length ≥ 1 cm with higher power and < 1 cm with lower power were utilized for ablating feeding vessels and nodules, especially those near anatomical structures, respectively. The therapeutic efficacy (volume reduction rate [VRR], complication rate, and regrowth rate) and technical outcomes (total energy delivery, ablated volume/energy, RFA time, and ablated volume/time) of FE and AE were compared. Continuous parameters were compared using a two-sample t-test or Mann-Whitney U test, and categorical parameters were compared using a chi-squared test or Fisher's exact test. Results: A total of 182 nodules (FE: 92 vs. AE: 90) in 173 patients (mean age ± standard deviation, 47.0 ± 14.7 years; female, 90.8% [157/173]; median follow-up, 726 days [interquartile range, 441-1075 days]) were analyzed. The therapeutic efficacy was comparable, whereas technical outcomes were more favorable for AE. Both electrodes demonstrated comparable overall median VRR (FE: 92.4% vs. AE: 84.9%, P = 0.240) without immediate major complications. Overall regrowth rates were comparable between the two groups (FE: 2.2% [2/90] vs. AE: 1.1% [1/90], P > 0.99). AE demonstrated a shorter median RFA time (FE: 811 vs. AE: 627 seconds, P = 0.009). Both delivered comparable median energy (FE: 42.8 vs. AE: 29.2 kJ, P = 0.069), but AE demonstrated higher median ablated volume/energy and median ablated volume/time (FE: 0.2 vs. AE: 0.3 cc/kJ, P < 0.001; and FE: 0.7 vs. AE: 1.0 cc/min, P < 0.001, respectively). Conclusion: Therapeutic efficacy between FE and AE was comparable. AE demonstrated better technical outcomes than FE in terms of RFA time, ablated volume/energy, and ablated volume/time.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.53-60
• /
• 2002

Motion of lung tumors from respiration has been reported in the literature to be as large as of 1-2 cm. This motion requires an additional margin between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV). While such a margin is necessary, it may not be sufficient to ensure proper delivery of Intensity Modulated Radiotherapy (IMRT) to the CTV during the simultaneous movement of the DMLC. Gated treatment has been proposed to improve normal tissues sparing as well as to ensure accurate dose coverage of the tumor volume. The following questions have not been addressed in the literature: a) what is the dose error to a target volume without gated IMRT treatment\ulcorner b) what is an acceptable gating window for such treatment. In this study, we address these questions by proposing a novel technique for calculating the 3D dose error that would result if a lung IMRT plan were delivered without gating. The method is also generalized for gated treatment with an arbitrary triggering window. IMRT plans for three patients with lung tumor were studied. The treatment plans were generated with HELIOS for delivery with 6 MV on a CL2100 Varian linear accelerator with a 26 pair MLC. A CTV to PTV margin of 1 cm was used. An IMRT planning system searches for an optimized fluence map ${\Phi}$ (x,y) for each port, which is then converted into a dynamic MLC file (DMLC). The DMLC file contains information about MLC subfield shapes and the fractional Monitor Units (MUs) to be delivered for each subfield. With a lung tumor, a CTV that executes a quasi periodic motion z(t) does not receive ${\Phi}$ (x,y), but rather an Effective Incident Fluence EIF(x,y). We numerically evaluate the EIF(x,y) from a given DMLC file by a coordinate transformation to the Target's Eye View (TEV). In the TEV coordinate system, the CTV itself is stationary, and the MLC is seen to execute a motion -z(t) that is superimposed on the DMLC motion. The resulting EIF(x,y)is inputted back into the dose calculation engine to estimate the 3D dose to a moving CTV. In this study, we model respiratory motion as a sinusoidal function with an amplitude of 10 mm in the superior-inferior direction, a period of 5 seconds, and an initial phase of zero.

• Progress in Medical Physics
• /
• v.25 no.3
• /
• pp.128-138
• /
• 2014

In gated radiation therapy (gRT), due to residual motion, beam delivery is intended to irradiate not only the true extent of disease, but also neighboring normal tissues. It is desired that the delivery covers the true extent (i.e. clinical target volume or CTV) as a minimum, although target moves under dose delivery. The objectives of our study are to validate if the intended dose is surely delivered to the true target in gRT and to quantitatively understand the trend of dose delivery on it and neighboring normal tissues when gating window (GW), motion amplitude (MA), and CTV size changes. To fulfill the objectives, experimental and computational studies have been designed and performed. A custom-made phantom with rectangle- and pyramid-shaped targets (CTVs) on a moving platform was scanned for four-dimensional imaging. Various GWs were selected and image integration was performed to generate targets (internal target volume or ITV) for planning that included the CTVs and internal margins (IM). The planning was done conventionally for the rectangle target and IMRT optimization was done for the pyramid target. Dose evaluation was then performed on a diode array aligned perpendicularly to the gated beams through measurements and computational modeling of dose delivery under motion. This study has quantitatively demonstrated and analytically interpreted the impact of residual motion including penumbral broadening for both targets, perturbed but secured dose coverage on the CTV, and significant doses delivered in the neighboring normal tissues. Dose volume histogram analyses also demonstrated and interpreted the trend of dose coverage: for ITV, it increased as GW or MA decreased or CTV size increased; for IM, it increased as GW or MA decreased; for the neighboring normal tissue, opposite trend to that of IM was observed. This study has provided a clear understanding on the impact of the residual motion and proved that if breathing is reproducible gRT is secure despite discontinuous delivery and target motion. The procedures and computational model can be used for commissioning, routine quality assurance, and patient-specific validation of gRT. More work needs to be done for patient-specific dose reconstruction on CT images.

• The Journal of Korean Physical Therapy
• /
• v.15 no.2
• /
• pp.182-195
• /
• 2003

This study investigated the effects of triamcinolone acetonide by iontophoretic transdermal drug delivery on anti-inflammatory action into the rats and which had carrageenan-induced hyperalgesia and edema in the feet, trauma-induced tissue damage in the thigh. Each group was treated under the fellowing conditions. 1. Group I : Control group 2. Group II : Application of direct current 3. Group III : Application of 0.1$\%$ triamcinolone acetonide solution 4. Group IV : Iontophoresis of 0.1$\%$ triamcinolone acetonide solution The degree of anti-inflammation was evaluated by the paw withdrawal latency, the change in volume of foot the change of paw edema, histological change in rats. 1. In paw withdrawal latency, group IV showed the most significant therapeutic effect than the other groups at 0, 3, 6 and 9 hours(p < 0.001). 2. In paw edema experiment in the foot, group IV showed the most significant effect than group I at 0, 3, 6 and 9 hours. It meant that there was effective anti-inflammatory reaction in group I (p < 0.001). 3. In the light microscopic observation, group IV showed the most significant reduction of haemorrhage, hyperemia and infiltrative inflammation. From the results, the iontophoresis with triamcinolone acetonide is more effective than using each groups. It is one of the effective physical agent which delivered large molecular weight drug into the body. The continuous study is needed for many interesting issues of iontophoretic transdermal drug delivery in new future.

• Journal of Pharmaceutical Investigation
• /
• v.40 no.3
• /
• pp.167-173
• /
• 2010

Repeated oral administration of hydrochlorothiazide, a loop diuretic, due to transient high blood levels, may cause adverse effects such as gastric disturbance, nausea, high blood sugar, and hyper lipidemia. Transdermal administration could avoid some of these systemic side effects and gastric disorders. We have developed a matrix using ethylene-vinyl acetate (EVA), a heat-processible and flexible material, for transdermal delivery of hydrochlorothiazide. Drug solubility was highest at 40% PEG-400 volume fraction. Drug release increased as concentration increased with a linear relationship between the release rate and the square root of loading dose. Increasing temperature increased drug release from the EVA matrix. The activation energy, measured from the slope of log P versus 1000/T, was 11.9 kcal/mol for a 2.5% loading dose from EVA matrix. Diethyl phthalate had the highest plasticizing effects on the release of hydrochlorothiazide. To increase the skin permeation of hydrochlorothiazide from the EVA matrix, enhancers such as the saturated fatty acids, the unsaturated fatty acids, and the non-ionic surfactants were added to the EVA matrix, and skin permeation was evaluated using a modified Keshary-Chien diffusion cell fitted with intact excised rat skin. Polyoxyethylene 23-lauryl ether showed the highest enhancing effects. In conclusion, transdermal delivery of hydrochlorothiazide could be improved from an EVA matrix containing plasticizer and permeation enhancer.

• The Journal of the Korea Contents Association
• /
• v.22 no.4
• /
• pp.665-676
• /
• 2022

The e-commerce had been expanding in the distribution channels, recently. Then, COVID-19 and social distancing rules led to a surge of online hypermarkets volume. In this study, we examined workplace environments of delivery drivers, firstly. Second, this study was also designed to examine the influencing factors of the perceived working environments change on the job satisfaction, dealing with the recent surge of work. We analyzed 324 data using various ways like descriptive statistics, one-way analysis of variance, factor analysis, and hierarchical regression analysis. The analysis revealed that their job satisfaction was lower than the average score and their working time was too long. In addition, the changes of the workplace environments were divided into labor intensity change and working condition change, which all had a significant effect on job satisfaction. So we should devise some long-term and short-term plans to make the level of job satisfaction among delivery drivers high on workplace environments.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.23 no.59
• /
• pp.105-118
• /
• 2000

The rise in population and the increase of urbanization and industrial growth has resulted in an ever-increasing volume of municipal solid waste that must be regularly collected, transported, and ultimately disposed of. Therefore, over the last decade the public, commercial and legislative awareness of environmental issues has been increased dramatically on earth particularly some industrial countries which has a shortage of landfill capacity. A quality, cost and delivery lead-time are usually considered as the competitive factors for each industry. However, the concepts of environmental issue are emerging common terms and concerns more seriously. More attention than ever is being focused on the recycling and source reduction techniques to reduce the total volume of waste. Unfortunately, however, a shortage of landfill capacity and increasing disposal cost requests a fundamental solution about the environmental issue. That is the remanufacturing which allow manufacturers to minimize waste, production cost and to turn end-of-life product into a profitable product. The objectives of this research were to growth the remanufacturing system by suggesting issues and implementation methods for the remanufacturing. In order to accomplish these objectives, we introduced backgrounds of appearance and benefits of the remanufacturing.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2008.09a
• /
• pp.33-37
• /
• 2008

The evidence of the Cargo tank volume is very important between Buyer and Seller for agreement each other for LNG Ship. CTS(Custody Transfer System) Radar type level gauging sensor to be measured for cargo volume. The data of Trim & List sensor to be compensated for measuring data which is original data of the CTS sensor. The latest days, the Buyer would have posed a problem both the location and the accuracy of trim/list sensor specially neared final stage of the ship's delivery. So, we would like to report the introducing to the trim/list sensor and the confirmation of actual location for the trim/list sensor.

• IE interfaces
• /
• v.20 no.4
• /
• pp.515-524
• /
• 2007

This paper introduces the methodology for restrict adjustment of 25 mail sorting centers including 3 new mail sorting centers to balance their work loads and minimize their operating costs. We calculated the capacity of mail sorting centers considering mail types and analyzed the collection/delivery mail volume of 214 post offices to measure the work loads of mail sorting centers. We also developed the mathematical model and genetic algorithm to find the optimal solution for this problem.