• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.965-969
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• 2006

This study investigated heat transfer characteristics between absorber and heat pipe used to extract heat from concentric evacuated tubular collectors. In order to experiment, T-type thermocouples are attached to a evaporator of heat pipe and absorber of inner tube. A wall temperature distribution of absorber and heat pipe were carried out by experimental method under actual various ir-radiance and outdoor conditions. As a result, As to increase an irradiance, a wall temperature of absorber and heat pipe is gradually increased. The heat pipe was required about 20min to obtain steady state operation after start up and operates stable during various irradiance conditions. And the collector efficiency was about $50{\sim}70%$ when a mass flow rate is about $1.3{\ell}/min$.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2591-2603
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• 2023

Simulating the Corrosion-Related Unidentified Deposit (CRUD) on the surface of fuel assemblies is necessary to predict the axial offset anomaly and the localized corrosion induced by the CRUD during the operation of nuclear power plants. A new CRUD model was developed to predict the formation of the CRUD deposits, considering the deposition and erosion mechanisms. The heat transfer and capillary flow within the CRUD were also considered to evaluate the boiling amount within the CRUD layer. This model predicted a CRUD deposit thickness of 44 ㎛ during a one-cycle operation of the Seabrook nuclear power plant. The CRUD deposition tended to accelerate and decelerate during the simulation, by being related to boiling mechanism on the deposits surface. Additionally, during a three-cycle operation corresponding to the refueling period, the CRUD deposition was saturated at a thickness of 80 ㎛, which was in good agreement with the suggested thickness for CRUD buildupin pressurized water reactors. Surface boiling on the thin CRUD deposits enhanced the acceleration of the deposition, even when the wick boiling properties were not favorable for CRUD deposition. To ensure the certainty of the simulation results, sensitivity analyses were conducted for the porosity, chimney density, and the constants employed in the proposed model of the CRUD.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.215-224
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• 2019

According to the recent civil engineering construction work site which is a complex process, development of multi-functional geotextiles is required. In this study, the characteristics of five different modified cross-section fiber yarns for the selection of wicking yarns were analyzed and yarns that can achieve target properties were selected. Experimental prototype geotextiles suitable for horizontal wicking drain property and reinforcement was developed and its tensile strength, 2% secant modulus, vertical water permeability, AOS, friction characteristics by the direct shear method, and vertical/horizontal wicking test were analyzed. These tests are conducted to verify the performance of the geotextiles with horizontal wick drain property, separation and reinforcement developed in this study. As a results of the indoor soil box test, it was confirmed that the geotextiles using the wicking yarn sufficiently exhibited the function of discharging excess pore water in the horizontal direction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.6
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• pp.607-613
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• 2010

A seawater distiller, in which the waste heat from a portable electric generator was used, with a multiple-effect diffusion still was designed. The waste gas from small generators commonly used in islands has not yet been used because it has less thermal energy; however, this waste gas can be used as a heat source for small-capacity distillers and as an additional heat source for solar stills. The proposed distiller comprises a series of closely spaced parallel partitions that are placed in contact with saline-soaked wicks. In the distiller, evaporation and condensation processes are repeated to recycle the thermal energy for increasing the distillate productivity. Experimental results show that the proposed distiller with only one-effect still can produce at least 6.7 kg/day of distilled water; the proposed distiller with a ten-effect still is expected to produce 43 kg/day of distilled water. This amount of distillate is approximately four times the maximum daily productivity of the solar stills, as determined in outdoor experiments.

• Korean Journal of Head & Neck Oncology
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• v.16 no.1
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• pp.9-13
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• 2000

Objectives: To determine the tumor interstitial fluid pressure(TIFP) in patients with head and neck cancerand predict radiotherapy outcome.Materials and Methods: In 12 biopsy proven primary head and neck cancer patients with accessible by direct inspection and palpation, and of sufficient thickness(>1cm) to permit accurate needle placement, we measured TIFP at cervical lymph node before and during radiotherapy using a modified wick-in-needle technique. Tumor size was measured clinically and radiologically. Results: The mean preradiotherapy TIFP was 23.4mmHg. Preradiotherapy TIFP had significant relationship with tumor size(p=0.0009). Preradiotherapy TIFP was not different between complete response group and partial or less response group(p=0.114). Radiotherapy outcome was not different between group with above and group with below average TIFP(p=0.09). Conclusion: The mean TIFP was elevated with 23.4mmHg before radiation therapy. Preradiotherapy TIFP had significant relationship with tumor size. It is not definitive that TIFP could be prognostic indicator of radiation response.

• Journal of Korean Biological Nursing Science
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• v.11 no.1
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• pp.92-98
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• 2009

Purpose: This study was aimed to investigate the colony counts by different disinfecting processes and duration of the operation for humidifiers in an intensive care unit (ICU) in Busan. Method: The four steps of disinfecting process were taken with four different humidifiers according to the use of disinfectant (1:100 $Deconex^{(R)}$ 50FF/nothing) and refilling water (tap water/distilled water). First, the colony counts using water sample from wick was conducted at 0 hr, 24 hr, and 48 hr respectively after turning on the humidifiers. Next, the colony counts using waterdrop from the outlet was done at 0 hr, 24 hr, 48 hr, and 72 hr respectively after turning on the humidifiers. Result: No colony was counted after disinfecting with 1:100 $Deconex^{(R)}$ 50FF until 72 hr after turning on the humidifiers. However, without disinfecting with $Deconex^{(R)}$ 50FF, the colony count was increased in the humidifiers from 24 hr after turning on the humidifiers. The result was the same regardless of the refilling water. Conclusion: According to the results, the study found that disinfection of humidifiers in the ICUs with 1:100 $Deconex^{(R)}$ 50FF every 72 hr is effective to remove general bacteria.

• Advances in Energy Research
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• v.4 no.4
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• pp.299-323
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• 2016

Cylindrical parabolic solar concentrators of small concentration ratio are attractive options for working temperatures around $120^{\circ}C$. The heat gained can be utilized in many applications such as air conditioning, space heating, heating water and many others. These collectors can be easily manufactured and do not need to track the sun continuously. Using a heat pipe as a solar absorber makes the system more compact and easy to install. This study is devoted to modeling a system of cylindrical parabolic solar concentrators of small concentration ratio (around 5) fitted with a heat pipe absorber with a porous wick. The heat pipe is surrounded by evacuated glass tube to reduce thermal losses from the heat pipe. The liquid and vapor flow equations, energy equation, the internal and external boundary conditions were taken into consideration. The system of equations was solved and the numerical results were validated against available experimental and numerical results. The validated heat pipe model was inserted in an evacuated transparent glass tube as the absorber of the cylindrical parabolic collector. A calculation procedure was developed for the system, a computer program was developed and tested and numerical simulations were realized for the whole system. An experimental solar collector of small concentration, fitted with evacuated tube heat pipe absorber was constructed and instrumented. Experiments were realized with the concentrator axis along the E-W direction. Results of the instantaneous efficiency and heat gain were compared with numerical simulations realized under the same conditions and reasonably good agreement was found.

• The korean journal of orthodontics
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• v.47 no.2
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• pp.100-107
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• 2017

Objective: To analyze the long-term changes in maxillary arch widths and buccal corridor ratios in orthodontic patients treated with and without premolar extractions. Methods: The study included 53 patients who were divided into the extraction (n = 28) and nonextraction (n = 25) groups. These patients had complete orthodontic records from the pretreatment (T1), posttreatment (T2), and postretention (T3) periods. Their mean retention and postretention times were 4 years 2 months and 17 years 8 months, respectively. Dental models and smiling photographs from all three periods were digitized to compare the changes in three dental arch width measurements and three buccal corridor ratios over time between the extraction and nonextraction groups. Data were analyzed using analysis of variance tests. Post-hoc multiple comparisons were made using Bonferroni correction. Results: Soft-tissue extension during smiling increased with age in both groups. The maximum dental width to smile width ratio (MDW/SW) also showed a favorable increase with treatment in both groups (p < 0.05), and remained virtually stable at T3 (p > 0.05). According to the MDW/SW ratio, the mean difference in the buccal corridor space of the two groups was $2.4{\pm}0.2%$ at T3. Additionally, no significant group ${\times}$ time interaction was found for any of the buccal corridor ratios studied. Conclusions: Premolar extractions did not negatively affect transverse maxillary arch widths and buccal corridor ratios. The long-term outcome of orthodontic treatment was comparable between the study groups.

• Journal of the Korean Society of Costume
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• v.56 no.8 s.108
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• pp.113-122
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• 2006

In this study, about forty teaching materials have been analyzed in order to examine tight skirt sewing methodtreated in basic process in a college and a fashion related educational institution. The study objects limited with a belt, back centered zipper, and back double slits on a tight skirt, and used fifteen suitable teaching materials in this study. The first study result appeared that every single teaching material suggested the different way of wick adhesion which is used in zipper slit, back slit, and belt part when the skit has been manufactured in order to do a form of clothes well. Secondly, it is the case of a back slit part used for the purpose of both functionality of action and decoration, and it is the section which varies a sewing and cutting way according to seam room width of a back middle seam. However, the majority of teaching materials appeared by being selecting the way how it had cut an inseam of the back center by the both upper part of back slit. Finally, the result showed that it mentioned mainly only both sided zipper sewing method if it seems to be easy to treat the majority in a basic process even though use of a console zipper Is general on a zipper sowing way recently for several years. Also, two forms are used in the belt manufacturing, and they are based with a waist line. However, the teaching materials that were used in this study presented only a manufacture way of the straight line on the waist belt.

• Journal of Mechanical Science and Technology
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• v.19 no.4
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• pp.1044-1051
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• 2005

The isothermal characteristics of a rectangular parallelepiped sodium heat pipe were inves­tigated for high-temperature applications. The heat pipes was made of stainless steel of which the dimension was $140\;m\;(L)\;{\times}\;95m\;(W)\;{\times}\;46 m\;(H)$ and the thickness of the container was 5 mm. Both inner surfaces of evaporator and condenser were covered with screen meshes to help spread the liquid state working fluid. To provide additional path for the working fluid, a lattice structure covered with screen mesh wick was inserted in the heat pipe. The bottom surface of the heat pipe was heated by an electric heater and the top surface was cooled by circulating coolant. The concern in this study was to enhance the temperature uniformity at the bottom surface of the heat pipe while an uneven heat source up to 900 W was in contact. The temperature distribution over the bottom surface was monitored at more than twenty six locations. It was found that the operating performance of the sodium heat pipe was critically affected by the inner wall temperature of the condenser region where the working fluid may be changed to a solid phase unless the temperature was higher than its melting point. The maximum temperature difference across the bottom surface was observed to be $114^{\circ}C$ for 850 W thermal load and $100^{\circ}C$ coolant inlet temperature. The effects of fill charge ratio, coolant inlet temperature and operating temperature on thermal performance of heat pipe were analyzed and discussed.