• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.29-34
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• 2020

The behavior of brittle fracture of electroless nickel immersion gold (ENIG) /Sn-3.0wt.%Ag-0.5wt.%Cu (SAC305) solder joints was evaluated. The pH of the electroless nickel plating solution for ENIG surface treatment was changed from 4.0 to 5.5. As the pH of the Ni plating solution increased, pin hole in the Ni-P layer increased. The thickness of the interfacial intermetallic compound (IMC) of the solder joint increased with pH of Ni plating solution. The high speed shear strength of the SAC305 solder joint on ENIG surface finish decreased with the pH of the Ni plating solution. In addition, the brittle fracture rate of the solder joint was the highest when the pH of the Ni plating solution was 5.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.499-509
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• 2012

The purpose of this study was to suggest implications by defining the concepts of school-level autonomy capacity (SAC) and by analyzing the teacher's perception on it. For the study, a survey was employed. The data generating sample consisted of 260 elementary and secondary school teachers, and the data was analyzed in the categories such as schools' level and characteristics as well as teachers' status and experience. As a result, the study indicated that there were highly statistical significances in the categories of teachers' status and experience, while there were no statistical significances in the category of schools' characteristics. The conclusions drawn from the study were as follows: First, the more educational authorities for school autonomy should be expanded and transferred to the schools in order to enhance the strategic capacity of SAC. Second, in order to enhance the human resource capacity of SAC, the educational environment encouraging teachers' professional development should be stabilized. Third, the school organizational culture should be reorganized transformatively and creatively in order to enhance the organizational management capacity of SAC.

• Journal of Welding and Joining
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• v.32 no.3
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• pp.60-67
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• 2014

The ability of electronic packages and assemblies to resist solder joint failure is becoming a growing concern. This paper reports on a study of high speed shear energy of Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder with different electroless Ni-P thickness, with $HNO_3$ vapor's status, and with various pre-conditions. A high speed shear testing of solder joints was conducted to find a relationship between the thickness of Ni-P deposit and the brittle fracture in electroless Ni-P deposit/SAC405 solder interconnection. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the fractured pad surface with and without $HNO_3$ vapor treatment. A scanning electron microscopy (SEM) and an energy dispersive x-ray analysis (EDS) confirmed that there were three intermetallic compound (IMC) layers at the SAC405 solder joint interface: $(Ni,Cu)_3Sn_4$ layer, $(Ni,Cu)_2SnP$ layer, and $(Ni,Sn)_3P$ layer. The high speed shear energy of SAC405 solder joint with $3{\mu}m$ Ni-P deposit was found to be lower in pre-condition level#2, compared to that of $6{\mu}m$ Ni-P deposit. Results of focused ion beam and energy dispersive x-ray analysis of the fractured pad surfaces support the suggestion that the brittle fracture of $3{\mu}m$ Ni-P deposit is the result of Ni corrosion in the pre-condition level#2 and the $HNO_3$ vapor treatment.

• Journal of Veterinary Clinics
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• v.24 no.1
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• pp.35-37
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• 2007

Eight dogs were presented with anal sacculitis with purulent exudates and/or open in the right or left anal sac. Patient dogs, ranging in size from 3-to-8 kg, were treated with closed anal sacculectomies, in which the balloon of a Foley catheter (No. 6, 1.5 ml) was used to facilitate surgical dissection of the sac. In all cases, the Foley catheter successfully distended the anal sac during its removal. Clinical signs associated with the diseased anal sac were abated In the all dogs for a follow-up period of one-to-three months. Anal sacculectomy is a good therapeutic option for cases of chronic anal sacculectomy or impaction. The use of a small Foley catheter to distend the anal sacs during surgery was easy, Inexpensive, and successful.

• Journal of Welding and Joining
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• v.35 no.3
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• pp.7-14
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• 2017

The effect of high temperature-moisture on corrosion and mechanical properties for Sn-0.7Cu, Sn-3.0Ag-0.5Cu (SAC305) solders on flexible substrate was studied using Highly Accelerated Temperature/Humidity Stress Test (HAST) followed by three-point bending test. Both Sn-0.7Cu and SAC305 solders produced the internal $SnO_2$ oxides. Corrosion occurred between the solder and water film near flexible circuit board/copper component. For the SAC305 solder with Ag content, furthermore, octahedral corrosion products were formed near Ag3Sn. For the SAC305 and Sn-0.7Cu solders, the amount of internal oxide increased with the HAST time and the amount of internal oxides was mostly constant regardless of Ag content. The size of the internal oxide was larger for the Sn-0.7Cu solder. Despite of different size of the internal oxide, the fracture time during three-point bending test was not significantly changed. It was because the bending crack was always initiated from the three-point corner of the chip. However, the crack propagation depended on the oxides between the flexible circuit board and the Cu chip. The fracture time of the three-point bending test was dependent more on the crack initiation than on the crack propagation.

• Journal of Korean Society of Forest Science
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• v.3 no.1
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• pp.1-4
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• 1963

Present experiment has been carried out in order to make clear the abnormalities of the female gametophyte formation and its relation to fertility, using the short-style of F. koreana, the results of which are summarized as follows : (1) Anatropous ovule has single integument with thick cell-layer and tiny nucellus consisting of nucella-epidermis and megaspore mother cell. (2) Meiotic division of megaspore mother cell takes place around middle or latter part of March, while that of microspore mother cell occurs from the end of September to the beginning of October. (3) Megaspore mother cell stage is long, and ranges from October to March next year. (4) Formation of mature embryo sac is not completed until the beginning of May, approximately one month after blooming. (5) Normal embryo sac is rare, most of the nucellus being devoid of embryo sac.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.12
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• pp.1418-1424
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• 2011

This study proposes the suggested amount of clothing (SAC) and examines the preferred amount of clothing (PAC) for thermal comfort in mild cold conditions. Six male and nine female college students were systematically exposed to mild cold conditions by reducing the amount of clothing (Step I, 1.2clo ${\rightarrow}$ Step II, 1.0clo ${\rightarrow}$ Step III, 0.8clo ${\rightarrow}$ Step IV, 0.7clo). The subjects were then asked to adjust the amount of clothing to attain overall thermal comfort until they maintained thermal comfort for 10 minutes without changing the amount of clothing (Step V). The experiment was carried out in a climatic chamber at $19.5^{\circ}C$, 50%R.H. Body composition was measured and individual cold climate adaptability was surveyed before starting the experiment. Rectal temperature ($T^{re}$), skin temperature ($T_{sk}$), and oxygen consumption ($\dot{V}O_2$) were measured and the overall thermal sensation was voted in each step. PAC was obtained from the garments weight selected by each subject in Step V. SAC was proposed based on the change of oxygen consumption (${\Delta}\dot{V}O_2$). As a result, males showed higher $\bar{T}_{sk}$ and greater $O_2$ than females (p<.01). SAC obtained from $\dot{V}O_2$ were 652.0 (SE 3.9) g/$m^2$ for males and 766.0 (SE 2.5) g/$m^2$ for females and it was significantly different between groups (p<.01). PAC of males and females were 1.6 and 1.5 times heavier than SAC. In conclusion, females were more sensitive to the cold stress and recommended larger amount of clothing than males.

• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.301-307
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• 2003

In this study, we Presented computational results on the blood flow in the sac of the Korean artificial heart. Two dimensional unsteady flow was assumed and we utilized a finite element commercial code ADINA to simulate the blood flow. Rigid body-solid contact were considered between the actuator and the blood sac and fluid-structure interaction between the blood and the sac. The three geometric models proposed in the design process were simulated to assess the hemodynamic characteristics of the models According to the computational results, a strong flow to the outlet and a stagnated flow region near the inlet were observed during systole. The sac was filled with blood and recirculating flow was generated near the outlet during diastole. Shear stress during systole had its extreme values near the outlet edge whereas the magnitude of shear stress values were relative)v high near the inlet edge and the contacting surface with the actuator.

• Kosin Medical Journal
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• v.33 no.3
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• pp.358-368
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• 2018

Objectives: To identify the relationship between surgical success rate and preoperative nasal mucosal thickness around the lacrimal sac fossa, as measured using computed tomography. Methods: We reviewed 33 eyes from 27 patients who underwent endoscopic dacryocystorhinostomy after diagnosis of primary nasolacrimal duct obstruction and who were followed-up with for at least six months between 2011 and 2014. We measured preoperative nasal mucosal thickness around the bony lacrimal sac fossa using computed tomography and analyzed patient measurements after classifying them into three groups: the successfully operated group, the failed operation group, and the non-operated group. Results: Surgery failed in six of the 33 eyes because of a granuloma at the osteotomy site and synechial formation of the nasal mucosa. The failed-surgery group showed a clinically significantly greater decrease in nasal mucosal thickness at the rearward lacrimal sac fossa compared with the successful-surgery group. However, nasal mucosal thickness of fellow eyes (i.e., non-operated eyes) was not significantly different between the two groups, and the location of the uncinate process did not appear to influence mucosal thickness. In the failed group, posteriorly located mucosal thickness of operated eye fossa was thinner than that of the non-operated eyes, but not significantly so. Conclusions: Our results from this quantitative anatomical study suggest that nasal mucosal thickness is a predictor of endoscopic dacryocystorhinostomy results.

• Journal of the Korean Wood Science and Technology
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• v.49 no.5
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• pp.482-490
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• 2021

This research was conducted to analyze the sound absorption effect of air-dried leaves from two evergreen tree species found in Korea's warm-temperate and subtropical regions. As eco-friendly sound absorption materials, Dendropanax morbiferusa, and Fatsia japonica leaves were prepared in three specimen units sizes 0.5 × 0.5 cm², 1.0 × 1.0 cm², and 2.0 × 2.0 cm², and each of them was formed at a thickness of 1.00 cm, 1.75 cm, and 2.50 cm. The measured sound absorption coefficients (SAC) for 18 conditions were comparatively analyzed in this study. The SAC of both tree species was significantly improved by increasing the dried leaf layer thickness. These results showed a more consistent and distinct trend for both tree species under the condition of 0.5 cm² in dried leaf size compared to other leaf specimen sizes. However, as the thickness increased, the difference in sound absorption effect according to the leaf size tends to decrease overall. In the case of D. morbiferus, there was no significant difference in SAC based on leaf size under the condition of 2.5 cm thickness (p < 0.05). The highest mean SAC was found in a 2.5 cm thick condition with a leaf size of 0.5 × 0.5 cm², 0.549 for D. morbiferusa, and 0.594 for F. japonica, respectively.