• Journal of the korean academy of Pediatric Dentistry
• /
• v.35 no.3
• /
• pp.446-455
• /
• 2008

The aim of this study was to evaluate the effect of fluoride varnish application on enamel decalcification. Eighty bovine enamel blocks divided randomly into 4 groups. Group I is the control group. Group II was treated with the APF gel and washed after 4 minutes. Group III and IV was treated with Fluor $Protector^{(R)}$ and $CavityShield^{TM}$ and washed after 1 minutes. Decalcification were created by placing all specimen into artificial acidic solution(pH 4.0). Then the optical density of the lesions were measured by visible light fluorescence and the lesion depths were measured. The results were : 1. The optical density of group II was higher than group I but lower than group III, IV(p<0.05) and there was no difference between group III, IV(p>0.05) at 48 hours. 2. The optical density of group IV was highest at 72 hours(p<0.05). 3. Mean lesion depths were $205.36{\pm}42.85{\mu}m$ and $210.81{\pm}44.60{\mu}m$ in group I, II but no significant difference between two groups(p>0.05). 4. Mean lesion depths were $80.03{\pm}21.66{\mu}m$ and $77.46{\pm}27.72{\mu}m$ in group III, IV but no significant difference between two groups(p>0.05). Fluoride varnish treatment resulted in a significant reduction in lesion depth compared with APF gel. Fluor $Protector^{(R)}$ and $CavityShield^{TM}$ provided the similar effect.

• Journal of Trauma and Injury
• /
• v.27 no.4
• /
• pp.145-150
• /
• 2014

Purpose: To assess the accuracy and role of single-contrast computed tomography (CT) in the management of anterior abdominal stab wound (AASW). Methods: During 8-years period, single-contrast CT was performed in 21 hemodynamically stable AASW patients (age range, 22-64 years; median age, 45 years), including 19 men and 2 women. CT scans were evaluated by one trauma surgeon and one senior resident to determine the depth of injury(peritoneal violation or not), and abnormal findings of intraperitoneal cavity associated with stab injury. We retrospectively reviewed medical records regarding operative findings. Results: Nine patients underwent abdominal surgery and 12 patients nonoperative management. In the abdominal surgery group, abnormal CT findings included peritoneal violation in 14 patients and abnormal intraperitoneal cavity findings in 5 patients. There was no statistical significant difference regarding abnormal CT findings between abdominal surgery group and nonoperative management group. Among the nine abdominal surgery patients, therapeutic laparotomy was performed on 4 patients. The positive predictive value (PPV) and negative predictive value (NPV) of peritoneal violation to predictive therapeutic laparotomy were 28.6% and 100%, respectively. In addition, the PPV and NPV of abnormal intraperitoneal cavity CT findings to predict therapeutic laparotomy were 40.0% and 87.5%, respectively. There was no statistical significant difference regarding the abnormal CT findings between therapeutic laparotomy group and non therapeutic laparotomy group. Conclusion: CT is a good adjunctive method to evaluate hemodynamicaly stable AASW patients. If peritoneal violation is not seen on CT scan, conservative treatment on local wound may be safely performed without additional abdominal surgery. However, further study is warranted to evaluate the exact role of CT in the diagnostic workup of AASW patients.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.4
• /
• pp.293-304
• /
• 2018

This paper described a results of field test based on plate bearing test of the restoration material, which was developed to restore the ground cavity due to sewerage damage. The analysis of bearing capacity characteristics on the restoration materials was performed by experimental results. The results showed that the load bearing capacity in the maximum stress condition of the foundation ground is about 66%-70%, when the expansion mat is embedded at the bottom of 0.1 m and 0.2 m from the ground surface. However, The load bearing capacity of expansion mat according to embedded depth was not large. The load bearing capacity of concrete mats was about 82%-90% compared with that of ground surface, and it showed about 50% of the load bearing capacity compared with the expansion mat. As a result of analysis of allowable bearing capacity according to restoration materials, it was confirmed that the allowable bearing capacity of the expansion mat and the concrete was about 130%-150% and about 160% more than the foundation ground, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.6
• /
• pp.566-572
• /
• 2021

A methodology for the identification and coordinates estimation of air cavities under urban ground or sandy soil using its natural poles and natural resonant frequencies is presented. The potential of this methodology was analyzed. Simulation models of PEC (Perfect Electric Conductor)s with various shapes and dimensions were developed using an EM (Electromagnetic) simulator. The Cauchy method was applied to the obtained EM scattering response of various objects from EM simulation models. The natural poles of objects corresponding to its instinct characterization were then extracted. Thus, a library of poles can be generated using their natural poles. The generated library of poles provided the possibility of identifying a target by comparing them with the computed natural poles from a target. The simulation models were made assuming that there is an air cavity under urban ground or sandy soil. The response of the desired target was extracted from the electromagnetic wave scattering data from its simulation model. The coordinates of the target were estimated using the time delay of the impulse response (peak of the impulse response) in the time domain. The MP (Matrix Pencil) method was applied to extract the natural poles of a target. Finally, a 0.2-m-diameter spherical air cavity underground could be estimated by comparing both the pole library of the objects and the calculated natural poles and the natural resonant frequency of the target. The computed location (depth) of a target showed an accuracy of approximately 84 to 93%.

• The Journal of Engineering Geology
• /
• v.27 no.2
• /
• pp.153-164
• /
• 2017

The geological factors for causing ground subsidence are very diverse. It can be affected by any geological or extrinsic influences, and even within the same geological factor, the soil depression impact factor can be determined by different physical properties. As a result of reviewing a large number of papers and case histories, it can be seen that there are seven categories of ground subsidence factors. The depth and thickness of the overburden can affect the subsidence depending on the existence of the cavity, whereas the depth and orientation of the boundary between soil and rock are dominant factors in the ground composed of soil and rock. In case of soil layers, more various influencing factors exist such as type of soil, shear strength, relative density and degree of compaction, dry unit weight, water content, and liquid limit. The type of rock, distance from the main fracture and RQD can be influential factors in the bedrock. When approaching from the hydrogeological point of view, the rainfall intensity, the distance and the depth from the main channel, the coefficient of permeability and fluctuation of ground water level can influence to ground subsidence. It is also possible that the ground subsidence can be affected by external factors such as the depth of excavation and distance from the earth retaining wall, groundwater treatment methods at excavation work, and existence of artificial facilities such as sewer pipes. It is estimated that to evaluate the ground subsidence factor during the construction of underground structures in urban areas will be essential. It is expected that ground subsidence factors examined in this study will contribute for the reliable evaluation of the ground subsidence risk.

• Tunnel and Underground Space
• /
• v.19 no.1
• /
• pp.19-30
• /
• 2009

For the purpose of determining the thickness of concrete lining and detect of the cavity where may be located behind tunnel lining, IE (Impact-Echo) method it effectively useful in the tunnel safety diagnosis and the quality control during the construction. As a part of case study, we applied IE method to various tunnel structure types such as road tunnel and subway tunnel constructed by NATM (New Austrian Tunnelling Method) and ASSM (American Steel Support Method). As tunnel specifications estimated from this method were compared with coring data, design drawing and other survey results, it was very good agreement with each other. In conclusion, we verified that IE method shows an accurate and reliable result. The conventional interpretation of IE method in frequency domain gives only vertical information at a certain point. However, the interpretation using time-frequency analysis and depth section imaging technique from two dimensional profiling surveys can show more reliable information about structure inside.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.2
• /
• pp.177-184
• /
• 2017

Many ground subsidence accidents have happened in Korea. The accident was caused by the subsidence and leakage of the deteriorated sewage pipe. This study aims to establish the empirical data of the ground penetration radar(GPR) detection for ground subsidence. A test bed was also manufactured for the same purpose. The GPR detection variables are embedment depth and horizontal distance of embedded cast iron pipe and expanded polystyrene(EPS). From the detection results, the EPS embedded by a depth of 1.5m was difficult for detection. The EPS closely embedded to the cast iron pipe within a 0.5m distance had a very strong cast iron pipe signal. Therefore, the detection was impossible. This study developed an image processing program, called the GPR image processing program(GPRiPP), to process the GPR detection results. Its major function is the gain function, which amplifies the wiggle wave signal. Compared to the existing programs, the GPRiPP is capable of showing a similar image processing performance.

• Animal Systematics, Evolution and Diversity
• /
• v.32 no.4
• /
• pp.272-280
• /
• 2016

Most scyphomedusae jellyfishes recorded in Korean waters are temperate and subtropical species. In the present study, two cold-water jellyfishes from Korean waters are first described. Scyphomedusae were collected from the coasts of Gangneung and Ulsan of the East Sea, and Boryeong, and the eastern area of the Yellow Sea from June 2006 to May 2015. Scyphomedusae collected in Ulsan and Gangneung were identified morphologically as Aurelia limbata Brandt, 1835. Their umbrella was 250-500 mm in width and 30-50 mm in height; the exumbrella was white and the subumbrella was dark brown in color. The vascular system was complex with anastomosed branches. Individuals of this species lived at about 6.6-9.9℃ and 30-50 m depth in Korean waters. Scyphomedusae collected from the center of the Yellow Sea and from Boryeong were identified as Parumbrosa polylobata Kishinouye, 1910. Their umbrella was disc-shaped, 80-200 mm in width and 20-40 mm in height. Its milky white gonads could be seen through the transparent exumbrella. The stomach cavity was round and flat with four interradial cavities connected by subgenital cavities, and the four oral arms were bifurcated and spear-head shaped. Individuals were found at about 6.4-10.0℃ and 40-90 m depth in Korean waters. The identities of both species were confirmed by molecular analysis using nuclear ribosomal DNA sequences.

• Journal of Yeungnam Medical Science
• /
• v.19 no.2
• /
• pp.116-125
• /
• 2002

Background: In patients with endometrial carcinoma, preoperative evaluation of exact staging has important prognostic and therapeutic implications. The incidence of pelvic and aortic lymph node involvement in endometrial carcinoma depends on grade of tumor differentiation and depth of myometrial invasion. Material and method: To evaluate whether MRI provides a preoperative assessment for staging of endometrial carcinoma, MRI was undertaken in 28 patients, a few weeks before operation. Myometrial invasion was devided in three categories, and involvement of cervix, adnexa, and pelvic cavity were classified. Results: The results of MR imaging were compared with these of pathology. The preoperative MRI staging of endometrial carcinoma was correct in 22 out of 28 patients. In the evaluation of myometrial invasion, the MR imaging underestimated in 4 cases and overestimated in 1 case. Conclusion: In patients with endometrial carcinoma, MR imaging is very useful in the assessment of the depth of myometrial invasion, stromal invasion of cevix, lymphatic & pelvic metastases and extent of the lesion.

• Restorative Dentistry and Endodontics
• /
• v.46 no.3
• /
• pp.33.1-33.12
• /
• 2021

Objectives: This study aimed to investigate the efficacy of ionic and non-ionic-based contrast media (in vitro study) and the combinatorial effect of chitosan-based endo-radiopaque solution (CERS) (in vivo study) for visualization of the root canal anatomy. Materials and Methods: In vitro study (120 teeth): The root canal of maxillary premolars and molars (in vitro group 1 and 2 respectively, n = 60 each) were analyzed using 4 different contrast media (subgroups: Omnipaque 350, Iopamidol, Xenetix 350, and Urografin 76; n = 15 each) in combination with 5.25% sodium hypochlorite (NaOCl). Based on the results of the in vitro study, in vivo study (80 teeth) was done to compare Xenetix 350 + 5.25% NaOCl with CERS (in vivo group 1 and 2 respectively, n = 40 each) on maxillary and mandibular premolars and molars. Two endodontists used radiovisiography to assess the depth of ingress and identify the aberrant root anatomy after access cavity preparation, and after initial cleaning and shaping of canals. Kruskal-Wallis test was used for in vitro comparison (p < 0.05), and Wilcoxon signed-rank test and Mann-Whitney U test for in vivo analysis (p < 0.01). Results: In vitro study, Xenetix 350 + 5.25% NaOCl facilitated a significant higher visualization (p < 0.05). For in vivo study, CERS had a statistically significant depth of ingress (p < 0.01), and was efficient in identifying the aberrant root canal anatomy of premolars and molars. Conclusions: CERS facilitates better visualization of the root canal anatomy of human premolars and molars.