• Journal of the Korean Geotechnical Society
• /
• v.28 no.9
• /
• pp.23-30
• /
• 2012

This paper is research results of slope stability analysis associated with seepage infiltration for unsaturated soil in debris-flow occurrence slopes. Site investigations were carried out in two slopes, located at Inje in Kangwon province where debris flow occurred in 2006 and at Yangpyung in Kyeunggi province where it occurred in 2010. For unsaturated soil sampled at the zone of debris-flow initiation, soil water characteristic curves with tempe pressure cells and shear strength parameters with newly designed shear strength apparatus were obtained respectively. The commertially available software SEEP/W was used to analyze seepage infiltration in unsaturated soil, based on their properties obtained from test results and the actual rainfall data at the moment of debris flow occurrence, and slope stability analysis with the program of SLOPE/W, associated with results of seepage analysis, was performed to simulate slope failure. As results of this research, seepage infiltration to unsaturated soil due to intensive rainfall was found to cause increase of ground water table as well as degree of saturation. Through this research slope stability analysis for unsaturated soil, considering the actual rainfall characteristic, might be a reasonable method of investigating characteristics of debris flow behavior, in particular, the moment of debris flow occurrence.

• Korean Journal of Clinical Pharmacy
• /
• v.12 no.1
• /
• pp.29-38
• /
• 2002

Hypertension is an important public health problem because it increases the risk of stroke, angina, myocardial infarction, heart failure, and end-stage renal disease. If it is not actively treated, morbidity and mortality increase with hypertension-induced complications and quality of life decreases. This study was to evaluate the use of antihypertensive drugs and blood pressure changes and to compare algorithms chosen (or the 1st and 2nd line therapy of hypertension based on the JNC VI recommendations. The medical charts of 222 patients with essential hypertension at St. Vincent's Hospital in Suwon from January 1997 to January 2000 were reviewed retrospectively. Data collection and analysis included baseline BP underlying diseases and complications, administered antihypertensives, BP changes, changes of antihypertensive regimen, and adverse effects with treatments. As results, the higher BP the patients had, the more frequent they had target organ damages and clinical cardiovascular diseases. Mean duration to reduce blood pressure less than 140/90 mmHg was 8 weeks in $85.3\%$ of the patients. The rate of control in BP was $82.4\%$ at 6 months. The major antihypertensive drugs prescribed were calcium channel blockers $(61.8\%)$ , ACE inhibitors $(19.1\%),\;\beta-blockers\;(13.7\%)$ and diuretics $(5.3\%)$ as the 1st-line monotherapy. The methods of treatment used as the 1st-line therapy were monotherapy$(59\%)$ and combination therapy $(41\%)$. Blood pressure change was significantly greater for combination therapy than monotherapy$(-26.2\pm21.4\;vs.\;-18.56\pm16.7$ mmHg for systolic blood pressure; P<0.003, $-16.9\pm13.2\;vs.\;-9.2\pm12.8$ mmHg for diastolic blood pressure; p<0.001). When blood pressure was not completely controlled with the first antihypertensive selected, the 2nd line therapy had 4 options: addition of 2nd agent from different class; $66.2\%$, substitution with another drug, $21.9\%$ increase dose $11.9\%$ continue first regimen $27.9\%$ Calcium channel blockers were the most frequently prescribed agents. This was not comparable to the JNC VI guideline which recommended diuretics and $\beta-blockers$ for the 1st-line therapy. Most of patients achieved the goal BP and maintained it until 6 months, but the remaining patients should be controlled more tightly to improve their BP with combination of life style modification, patient education, and pharmacotherapy.

• Research in Community and Public Health Nursing
• /
• v.12 no.1
• /
• pp.226-238
• /
• 2001

This study was attempted to understand experiences of the users of natural family planning(NFP) by applying Q-methodology. 37 statements were used to Q population through literature research and interviews. For the P sample. I interviewed personally 30 people who had taken a lesson in NFP for over 6 months and had been using and experiencing it autonomously for more than 2 years so far, and asked them to Q-classify the statement cards in order of the degree of approval, from the one they most approved to the one they least approved. Data were coded and input into a computer and were analyzed using QUANL PC Program. In this study, I discovered 4 types of experiences by the users of NFP and named them each according to their features: the first, a type of mutual control with morality, the second, a type of the pursuit of mutual -cooperation, the third. a type of the pursuit of conviction. and the fourth, a type of the perception of health management. The first type said that NFP was a good contraceptive way in which no drug or devices are used, that the husband's cooperation was needed, and that they became able to control sexual desire with morality. The second type perceived that continuous efforts were required to put NFP in practice, that the, husband's cooperation was essential, and that dialogues between husband and wife were also necessary to use it, and as such they regarded mutual cooperation between husband and wife as highly important. On the other hand. the third type perceived that one's conviction played a big part, that knowledge of physiological changes was useful and the ability to sense physical changes improved. and that one's willpower was important. and thus they regarded one's own willpower as most important. The fourth type reported that this method was a good way to control pregnancy and should be taught about at the beginning of sex education. and thus they were emphasizing the importance of NFP as a helpful way to manage one's health. 1. therefore, intend to provide the following suggestions based on the result of this study. 1) It is necessary to develop a program that allows NFP to be applied to sex education program. 2) It is necessary to analyze factors that affect the execution of NFP. 3) It is necessary to analyze causes of failure of those who fail to execute NFP.

• Journal of Ocean Engineering and Technology
• /
• v.19 no.5 s.66
• /
• pp.43-49
• /
• 2005

This paper is to investigate the effect of corrosion by acoustic emission method in tensile loading and the adhesiveness between substrate and coating layer. The powders used are Zn and Amdry625, respectively. They are coated on brass alloy substrate. AE signals of Zn and Amdry625 coating layer increase drastically in strain $2\%$. However, those of Zn specimen have more than those of Amdry625 specimen. When the specimens executed the corrosion test under $3.5\%$ NaCl solution for 500, 1000 hours, the salt solution penetrated into the surface of the substrate through the pores of the coating layer. As a result, corrosion production formed on the surface of the substrate. The adhesiveness between coating layers is weakened by the polarization and corrosion itself. The AE event, count, and energy of corroded coating specimens decrease, compared to specimens without corrosion. The results are summarized as follows : 1. In the tensile tests, the time that it took to start and develop the cracks and exfoliations between the surface of the substrates and the plasma spray coatings were different according to the type of plasma sprayed material, which are Zn and Amdry625. These phenomena were obvious at the strain rate 1 to $5\%$, and few available data were found after that stage. 2. The specimens with Zn coating showed the characteristics of crack, according to the changes of the tensile strength applied on the substrates while those with Amdry625 showed exfoliation as a result of low adaptation to the tensile strength. 3. The anti-corrosion specimens showed that the adhesive properties between the substrate and the plasma spray coating were strong in the order of Zn, Amdry. It showed that Corroded specimens cracked or exfoliated easily, even with the small energy, because those had a comparatively weakened adhesive property, due to corrosion. 4. Zn specimen showed no corrosion phenomena on the surface of the substrates, because they had the function of sacrifice anode however, Amdry625 specimen showed the corrosion, because it did not have that function.

• The Journal of Korean Academy of Prosthodontics
• /
• v.35 no.3
• /
• pp.566-576
• /
• 1997

This study was performed to evaluate the tensile strength of solder joint in titanium and the wettability of 14K gold solder on titanium. Two pieces of titanium rod 30 mm in length and 3mm in diameter were butt-soldered with a 14K gold solder using the electric resistance heating under flux-argon atmosphere, the infrared heating under argon atmosphere, and the infrared heating under vacuum-argon atmosphere. A tensile test was performed at a crosshead speed of 0.5 mm/min, and fracture surfaces were examined by SEM. To evaluate the wettability of 14K gold solder on titanium, titanum plates of a $17{\times}17{\times}1mm$ were polished with #80-#2000 emery papers, and the spreading areas of solder 10 mg were measured by heating at 840 * for 60 seconds. The solder-matrix interface regions were etched by the solution of 10% KCN-10% (NH4)2S2O8, and analyzed by EPMA. The results obtained were summarized as follows ; 1. The maximum tensile strength was obtained when the titanium surface was polished with #2000 emery paper and soldered using the electric resistance heating under flux-argon atmosphere. Soldering strengths showed the significant difference between the electric resistance heating and the infrared heating(p<0.05). 3. The fracture surfaces showed the aspect of brittle fracture, and the failure developed along the interfaces of solder-matrix reaction zone. 4. The EPMA data for the solder-matrix interface region revealed that the diffusion of Au and Cu occurred to the titanium matrix, and the reaction zone showed the higher contents of Au, Cu and Ti than others.

• Journal of Elementary Mathematics Education in Korea
• /
• v.23 no.1
• /
• pp.59-74
• /
• 2019

According to previous studies, it shows that the metacognitive ability that makes the positive element of the problem solver positively affects the problem-solving process of mathematics. In order to accurately grasp causality, this study investigates the specific characteristics of the meta-affect factor in the process of problem-solving. To do this, we analyzed the types and frequency of data collected from collaborative problem-solving situations composed of 4th~6th grade mathematically gifted children in small group of two. As a result, it can be seen that the type of meta-affect in the problem-solving process of mathematically gifted children is related to the correctness rate of the problem. First, regardless of the success or failure of the problem-solving, the meta-affect appeared relatively frequently in the meta-affect types in which the cognitive factors related to the context of problem-solving appeared first, and acted as the meta-functional type of the evaluation and attitude. Especially, in the case of successful problem-solving of mathematically gifted children, meta-affect showed a very active function as meta-functional type of evaluation.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.1
• /
• pp.1-7
• /
• 2008

When historical or cultural buildings need to be repaired or reinforced, the changes of original features should be minimized, and the strengths of structures should be improved. Among the existing methods to reinforce historical wood structures, the carbon fiber reinforcement polymer (CFRP) installation method is one of the best ones to achieve the afore-mentioned requirements. Therefore, this study aims at investigating the reinforcing effects and failure modes of timber beams reinforced with the inserted CFRP, a part of roof trusses in modern wood structures, and at providing the fundamental test data to estimate the CFRP rein-forced timber beam in the application of this reinforcing method. The primary parameters in this study were the layout and amount of CFRP. It was observed that, when $0.3{\sim}0.7%$ of CFRP were installed, the strengths of reinforced timber beams increased up to 173% compared to its original strength, but their strengthening effects were heavily influenced by the characteristics of timber such as burls. In order to improve the applicability of this strengthening method, fundamental understandings on the characteristics of wood would be necessary, and there would be in need of researches on the non-destructive test for wood structures as well.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.6
• /
• pp.541-549
• /
• 2008

The fatigue analysis is performed to avoid structural failure in aerospace structures under repeated loads. In this paper, the fatigue life is estimated for the design of tilt rotor UAV. First of all, the fatigue load spectrum for tilt rotor UAV is generated. Fatigue analysis is done for the flaperon joint which may have FCL(fracture critical location). Tilt rotor UAV operates at two modes: helicopter mode such as taking off and landing; fixed wing mode like cruising. To make overall fatigue load spectrum, FELIX is used for helicopter mode and TWIST is used for fixed wing mode. The other hand, the Kriging meta model is used to get S-N regression curve for whole range of material life when S-N test data are analyzed. And then, the second order of S-N curve is accomplished by the least square method. In addition, the coefficient of determination method is used to ensure how accuracy it has. Finally, the fatigue life of flaperon joint is compared with that obtained by MSC. Fatigue.

• Restorative Dentistry and Endodontics
• /
• v.35 no.2
• /
• pp.106-115
• /
• 2010

The purpose of this study was to evaluate the microtensile bond strength (${\mu}TBS$), failure modes and bonding interfaces of self-etching and three self-adhesive resin cements to dentin and indirect composite resin. Cylindrical composite blocks (Tescera, Bisco Inc.) were luted with resin cements (PA: Panavia F 2.0, Kuraray Medical Inc., RE: RelyX Unicem Clicker, 3M ESPE., MA: Maxem, Kerr Co., BI: BisCem, Bisco Inc.) on the prepared occlusal dentin surfaces of 20 extracted molars. After storage in distilled water for 24 h, $1.0\;mm\;{\times}\;1.0\;mm$ composite-dentin beams were prepared. ${\mu}TBS$ was tested at a cross-head speed of 0.5 mm/min. Data were analyzed with one-way ANOVA and Tukey's HSD test. Dentin sides of all fractured specimens and interfaces of resin cements-dentin or resin cements-composite were examined at FESEM (Field Emission-Scanning Electron Microscope). In conclusion, PA and RE showed higher bond strength and closer adaptation than MA and BI when indirect composite blocks were luted to dentin using a self-etching and three self-adhesive resin cements.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.3
• /
• pp.95-104
• /
• 2005

To know the proper setup posture for the various clubs, changes of setup variables according to the change of golf club length was investigated. Swing motions of three male low handicappers including a professional were taken using two high-speed videocameras. Four clubs iron 7, iron 5, iron 3 and driver (wood 1) were selected for this experiment. Three dimensional motion analysis techniques were used to get the kinematical variables. Mathcad and Kwon3D motion analysis program were used to analyze the position, distance and angle data in three dimensions. The variables divided into three categories 1) position and width of anterior-posterior direction 2) position and width of lateral direction 3) angles and evaluated based on the theories of many good golf teachers. Major findings of this study were as follows. 1.The stance (distance between ankle joints) was increased as the length of the club increased but the increasing width was not large. It ranges from 5cm to 10cm and professional player showed small changes. 2. Forward lean angle of trunk was decreased (more erected) as the length of the club increased. It ranges from 30 degrees for iron7 to 25 degrees for driver. 3. Angle between horizontal and right shoulder were increased as the length of the club increased. It ranges from 10 degrees to 20 degrees and professional player showed small changes. 4. Anterior-posterior position of the shoulders were located in front of the foot for all clubs and the difference between the shoulder and knee position was decreased as the length of the club increased. 5. Anterior-posterior position of grip (hand) was located almost beneath the shoulders (2.5cm front) for iron7, but it increased to 10cm for the driver. This grip adjustment makes the height of the posture increased only 5cm from iron7 to driver. 6. Lateral position of grip located at 5cm left for the face of iron7, but it located at the right side (behind) for the face of driver. 7. Lateral position of the ball located at the 40%(15cm) of stance from left ankle for iron7 and located at the 10% (5cm) of stance for driver. 8. Head always located at the right side of the stance and the midpoint of the eyes located at the 37% of stance from the right ankle for all clubs. This means that the axis of swing always maintained consistently for all clubs. 9. Left foot opened to the target for all subject and clubs. The maximum open angle was 25 degrees. Overall result shows that the changes of the setup variables vary only small ranges from iron7 to driver. Paradoxically it could be concluded that the failure of swing result from the excessive changes of setup not from the incorrect changes. These findings will be useful for evaluating the setup motion of golf swing and helpful to most golfers.