• Journal of Soil and Groundwater Environment
• /
• v.13 no.4
• /
• pp.8-21
• /
• 2008

A series of three-dimensional numerical simulations using a hydrodynamic dispersion numerical model is performed to analyze quantitatively impacts of layered heterogeneity of geologic media and groundwater pumping schemes on groundwater flow and salt transport in coastal aquifer systems. A two-layer heterogeneous coastal aquifer system composed of a lower sand layer (aquifer) and an upper clay layer (aquitard) and a corresponding single-layer homogeneous coastal aquifer system composed of an equivalent lumped material are simulated to evaluate impacts of layered heterogeneity on seawater intrusion. In addition, a continuous groundwater pumping scheme and two different periodical groundwater pumping schemes, which withdraw the same amount of groundwater during the total simulation time, are applied to the above two coastal aquifer systems to evaluate impacts of groundwater pumping schemes on seawater intrusion. The results of the numerical simulations show that the periodical groundwater pumping schemes have more significant adverse influences on groundwater flow and salt transport not only in the lower sand layer but also in the upper clay layer, and groundwater salinization becomes more intensified spatially and temporally as the pumping intensity is higher under the periodical groundwater pumping schemes. These imply that the continuous groundwater pumping scheme may be more suitable to minimize groundwater salinization due to seawater intrusion. The results of the numerical simulations also show that groundwater salinization in the upper clay layer occurs significantly different from that in the lower sand layer under the periodical groundwater pumping schemes. Such differences in groundwater salinization between the two adjacent layers may result from layered heterogeneity of the layered coastal aquifer system.

• Journal of Oral Medicine and Pain
• /
• v.35 no.1
• /
• pp.83-91
• /
• 2010

Objectives: This study aimed to assess the characteristics of temporomandibular disorder (TMD) symptoms and to determine the correspondence between TMD symptoms and clinical examination findings. Material and methods: A total of 218 patients (143 females and 75 males; age=$31.3{\pm}14.0$) were enrolled in this study who completed a questionnaire and underwent a clinical examination and radiographic assessment. Patients were asked about all the symptoms and complaints, including onset or duration, and locations of the symptoms. Clinical examination included amounts of mouth opening, palpable temporomandibular joint (TMJ) sounds, and tenderness to palpation of the TMJ and all masticatory muscles. Tenderness scores obtained from palpation of the masticatory system were summated to define the variables for further analysis. Results: Pain was the most frequently reported symptom (78.9%), followed by joint sounds (45.4%), and limitation in mouth opening (17.0%). Jaw pain comprised 91.9% of pain complaints. The subjective intensity of jaw pain was low to medium in most patients (93.7%), but it was poorly correlated with the sum of tenderness scores of the TMJ and masticatory muscles (Kendall tau = 0.084). In contrast, the side in which pain was reported by patients was well associated with the clinical examination results (pain of the right side, p < 0.001, and left side, p < 0.001). There was moderate agreement in TMJ sounds between the side identified by patients as symptomatic and clinical examination findings (kappa = 0.482). Finally, patients who complained of restricted mouth opening showed about a 10 mm less opening in all three measurements, compared to other patients (p < 0.001). Conclusion: The most frequent symptoms reported by TMD patients were jaw pain, TMJ sounds, and mouth opening limitation. The side of jaw pain, the side of TMJ sounds, and the presence of opening limitation were highly concordant between symptom reports and examination findings.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.1
• /
• pp.11-18
• /
• 2004

The eruption of permanent teeth represents the movement in the alveolar bone before appearance in oral cavity, to the occlusal plane after appearance in oral cavity, and additive movement after reaching th the occlusal plane. Tooth eruption is mostly controlled by genetic signals. The eruption stage is divided to preeruptive alveolar stage, alveolar bone stage, mucosal stage according to the process of growth and development. If the disturbance is occured in any stage of eruption, tooth does not erupt. The cause of eruption disturbance are ectopic position of the tooth germ, obstruction of the eruption path and defects in the follicle or PDL. In the treatment of eruption disturbance, surgical procedures are commonly used. There are three kind of surgical procedure ; surgical exposure, surgical repositioning, surgical exposure and traction Surgical exposure is basic procedure. This involves removal of mucosa, bone, lesion that are surrounding the teeth, dental sac when necessary to maintain a patent channel between the crown and the normal eruptive path into the oral cavity. To ensure this patency, many techniques including cementation of a celluloid crown, packing with gutta-percha or zinc oxide-eugenol, or a surgical pack, are used. When surgical exposure is conducted, operators should not expose any part of cervical root cement and not injure periodontium or root of adjunct tooth. After surgical exposure, tooth should be surrounded by keratinized gingiva. There is direct relationship between the extent of development of pathophysiologic aberrations and the intensity of the manipulative injury inflicted on the tooth by surgical treatment, so operator should consider this thing. In these cases, surgical exposure is conducted on Maxillary 1st milars that have a eruption disturbance and improve the eruption disturbance effectively.

• Journal of the Korea Concrete Institute
• /
• v.18 no.3 s.93
• /
• pp.331-338
• /
• 2006

This paper presents the experimental results on volumetric changes in ordinary portland cement concrete made with various water-to-cement ratios(W/C's) ranging from 0.32 to 0.50 and cured in low different conditions. Curing regimes employed in this work were designed to exhibit autogenous and drying shrinkage as well as swelling of concrete. The concrete avoided any moist evaporation(Regime f showed only autogenous shrinkage and the lower the W/C, the feater the autogenous shrinkage. The concrete exposed to air drying conditions at $20{\pm}1^{\circ}C$ and $60{\pm}3%$ RH after 6-day water curing at $20{\pm}1^{\circ}C$(Regime II) swelled and then started to shrink. The maximum swelling value of concrete developed in water curing was between 15 and $40{\pm}10^{-6}$, and the greatest total shrinkage(autogenous+drying shrinkage) was obtained for the mixture made with W/C of 0.32. The concrete let to air drying conditions(Regime III) showed greater total shrinkage compared to the concrete cured in Regime II. The concrete exposed to air drying condition after 6-day sealed curing(Regime IV) exhibited slightly smaller total shrinkage than that of the concrete cured in Regime III. Net drying shrinkage that can be derived from the results of Regime I, III, and IV increased as the W/C increased despite of similar total shrinkage. This result indicated that drying shrinkage governs total shrinkage of high-W/C concretes. In other words, a portion of autogenous shrinkage in total shrinkage increased in low-W/C concretes. Therefore, it should be controlled in terms of cracking potential. Finally, total shrinkage of high-strength and high-performance concrete made with low W/C can be effectively reduced by appropriate early moisture curing.

• Journal of the Korea Concrete Institute
• /
• v.19 no.4
• /
• pp.515-525
• /
• 2007

In this investigation, results of laboratory tests on four reinforced concrete flat plate interior connections with elongated rectangular column support which has been used widely in tall residential buildings are presented. The purpose of this study is to evaluate an effect of column aspect ratio (${\beta}_c={c_1}/{c_2}$=side length ratio of column section in the direction of lateral loading $(c_1)$ to the direction of perpendicular to $c_1$) on the hysteretic behavior under earthquake type loading. The aspect ratio of column section was taken as $0.5{\sim}3\;(c_1/c_2=1/2,\;1/1,\;2/1,\;3/1)$ and the column perimeter was held constant at 1200mm in order to achieve nominal vertical shear strength $(V_c)$ uniformly. Other design parameters such as flexural reinforcement ratio $(\rho)$ of the slab and concrete strength$(f_{ck})$ was kept constant as ${\rho}=1.0%$ and $f_{ck}=40MPa$, respectively. Gravity shear load $(V_g)$ was applied by 30 percent of nominal vertical shear strength $(0.3V_o)$ of the specimen. Experimental observations on punching failure pattern, peak lateral-load and story drift ratio at punching failure, stiffness degradation and energy dissipation in the hysteresis loop, and steel and concrete strain distributions near the column support were examined and discussed in accordance with different column aspect ratio. Eccentric shear stress model of ACI 318-05 was evaluated with experimental results. A fraction of transferring moment by shear and flexure in the design code was analyzed based on the test results.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.2
• /
• pp.96-113
• /
• 1996

It has been found that the misfit dislocations in heavily boron-doped layers originate from wafer edges. Moreover, the propagation of the misfit dislocation into a heavily boron-doped region can be suppressed by placing a surrounding undoped region. Using a surrounding undoped region the disloction-free heavily boron-deoped silicon membranes have been fabricated. The measured surface roughness, fracture strength, and residual tensile stress of the membrane are 20.angs. peak-to-peak, 1.39${\times}$10$^{10}$ and 2.7${\times}$10$^{9}$dyn/cm$^{2}$, while those of the conventional heavily boron-doped silicon membrane with high density of misfit dislocations are 500 peak-to-peak, 8.27${\times}$10$^{9}$ and 9.3${\times}$10$^{8}$dyn/cm$^{2}$ respectively. The differences between these two membranes are due to the misfit dislocations. Young's modulus has been extracted as 1.45${\times}$10$^{12}$dyn/cm$^{2}$ for both membranes. Also, the effective lattice constant of heavily boron-doped silicon, the in-plane lattice constant of the conventional membrane, and the density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as 5.424.angs. 5.426.angs. and 2.3${\times}$10$^{4}$/cm for the average boron concentration of 1.3${\times}$10$^{20}$/cm$^{-23}$ cm$^{3}$/atom. Without any buffer layers, a disloction-free lightly boron-doped epitaxial layer with good crsytalline quality has been directly grown on the dislocation-free heavily boron-doped silicon layer. X-ray diffraction analysis revealed that the epitaxial silicon has good crystallinity, similar to that grown on lightly doped silicon substrate. The leakage current of the n+/p gated diode fabricated in the epitaxial silicon has been measured to be 0.6nA/cm$^{2}$ at the reverse bias of 5V.

• Journal of Oral Medicine and Pain
• /
• v.33 no.1
• /
• pp.41-48
• /
• 2008

The focus of this study is to analyze the effect of stress on the health of bruxism patients using the MBTI system. The most common personality type will be identified among the bruxism patients and by understanding their personality & their handling of stress, more comprehesive and effective treatment plan can be constructed. The study will also conclude that the type of personality has big effect on the cause of bruxism, and that this will be considered in the treatment plan in this hospital. The result of the study is as follow. First, more bruxism patients were type I than type E. It can be suggested that this result is due to the introversive people maintaining their energy how within themselves, and private are less to likely to release there stress than the expressive people. Second, among the bruxism patients significantly more type T were found compared to type F. This implies the bruxism tend to follow principals, scientific and analysing during decision making rather than basing their decision an meanings, emotions and influences. Thirdly, more bruxism patients clarified into ST in comparison to non-bruxism patients. This is thought to be due to probable increased stress and anxiety following ST people's tendency to more strict and realistic thinking according to effectiveness, evidence-based and productivity. Fourth, the type IJ was the most of the bruxism patients. We can come to the conclusion that decision-oriented introversion people who have hard to change, a thoroughgoing preparation characters are likely to grind their teeth by their detailed characters. Fifth, the type IT was the most of the bruxism patients. Bruxism patients are usually influenced by spirit, easily hearted, awed of relationship and attention. So, their intensity of stress is much bigger because of their personality. The last, Type IS was the most of the bruxism patients. It means that introvert sensitive types who have characters of calm, passive but defence to other's emotion, also neutral, keep moderation, and have cold-heartedness are likely to grind their teeth frequently. In conclusion it is evident that bruxism patients have particular personality types. Precisive, analysing and introversive bruxism patients are expected to have higher sensitivities to stress.

• Journal of Oral Medicine and Pain
• /
• v.32 no.1
• /
• pp.1-8
• /
• 2007

The purpose of this study was to investigate whether there were any changes in taste sensitivity with recurrent aphthous ulceration. Nintyseven subjects(25 males and 72 females) were included for the study and they were categorized into 2 groups(recurrent aphthous ulceration 27 persons, control 70 persons), recurrent aphthous ulceration group was investigated in the department of Oral Medicine, College of Dentistry, Pusan National University from April, 2005 to August, 2006 and control group was investigated in the clinic at Incheon city from June, 2006 to August, 2006. The electrical taste thresholds were measured using an electrogustometer of the 4 different sites(tongue tip, tongue lateral, circumvallate papilla and soft palate) in oral cavity. The results were as follows ; 1. The electrical taste threshold showed significant lower in the RAU group. 2. The electrical taste threshold showed significant lower in female group, and showed significant lower except soft palate in male group of the RAU group. 3. The electrical taste threshold showed a tendency to increase in all site of the multiple RAU group, but there were no significant differences. 4. The electrical taste threshold showed a tendency to increase in tongue lateral of the acute RAU group, and showed a tendency to increase in tongue tip, circumvallate papilla, soft palate of the chronic RAU group. 5. After treatment, electrical taste threshold was significant increase than initial visit in the RAU group. 6. After treatment, NAS showed a tendency to decrease in the RAU group.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.3
• /
• pp.391-399
• /
• 2004

The purpose of this study was to compare curing efficiency of newly developed curing units to traditional halogen curing unit by measuring thermal change and surface microhardness according to curing light system. Materials and mathods : The types of curing units were traditional low intensity halogen light(Optilux 360), plasma arc light(Flipo), low heat plasma arc light(Aurys), low intensity LED(Starlight), and high intensity LED(Freelight2). Temperature at the tip of light guide was measured by a digital thermometer using K-type thermocouple. And after resin was filled to 2, 3, 4mm teflon mold, bottom temperature measured during curing. After 24 hours, microhardness of top surface and bottom surface of each resin specimen were measured. Results : The result of this study can be summarized as follows, 1. As measuring temperature of curing unit tips, Flipo is the highest as $52.4^{\circ}C,\;Freelight2(37.86^{\circ}C),\;Optilux360(32.68^{\circ}C),\;Aurys(32.34^{\circ}C),\;and\;Starlight(26.14^{\circ}C)$ were followed. 2. Flipo and Freelight2 were the highest similarly and Optilux360 and Aurys were similarly next and Starlight was lowest in temperature of bottom surface of resin mold. 3. Microhardness of top surface were generally similar, and Aurys was relatively low. 4. Optilux 360 and Freelight2 were the highest, and Flipo, Starlight, and Aurys were followed in microhardness of bottom surface. Conclusions : The results suggest that careful use of Flipo and Freelight2 might be able to cure greater depth of resin composite and do not cause thermal problems than other curing units.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.23 no.3
• /
• pp.191-200
• /
• 2017

Proper packaging design can meet both the environmental and economic aspects of packaging materials by reducing the use of packaging materials, waste generation, material costs, and logistics costs. Finite element analysis(FEM) is used as a useful tool in various fields such as structural analysis, heat transfer, fluid motion, and electromagnetic field, but its application in the field of packaging is still insufficient. Therefore, the application of FEM to the field of packaging can save the cost and time in the future research because it is possible to design the package by computer simulation, and it is possible to reduce the packaging waste and logistics cost through proper packaging design. Therefore, this study investigated the FEM papers published in Korea for the purpose of helping research design using FEM program in the field of packaging in the future. In this paper, we analyzed the 29 papers that were directly related to the analysis of FEM papers published in domestic journals from 1991 to 2017. As a result, we analyzed the research topic, FEM program, and analysis method using each paper, and presented the direction that can be applied in future packaging field. When the FEM is applied to the packaging field, it is possible to change the structure and reduce the thickness through the stress and vibration analysis applied to the packaging material, thereby reducing the cost by improving the mechanical strength and reducing the amount of the packaging material. Therefore, in the field of packaging research in the future, if the FEM is performed together, economical and reasonable packaging design will be possible.