• Journal of Periodontal and Implant Science
• /
• v.43 no.5
• /
• pp.215-220
• /
• 2013

Purpose: Cigarette smoking is a major risk factor in periodontal diseases. The pathogenesis of periodontal diseases may be affected by alterations of the inflammatory response by smoke. Nitric oxide (NO) is a gaseous, colorless, highly reactive, short-lived free radical with a pivotal role in the regulation of various physiological and pathological mechanisms in the body. It is important in host defense and homeostasis, on the one hand, whereas, on the other hand, it modulates the inflammatory response in periodontitis, leading to harmful effects. The aim of this study was to assess the levels of NO in both the serum and saliva of smokers and nonsmokers having chronic periodontitis and to compare them with periodontally healthy controls. Methods: Sixty subjects participated in the study and were divided into three groups: group I, healthy nonsmoking subjects; group II, nonsmoking patients with chronic periodontitis; group III, smoking patients with chronic periodontitis. Each group consisted of twenty subjects. The biochemical estimation of NO in the collected serum and in the saliva was performed using the Griess colorimetric reaction. Results: The results showed that the mean value of the salivary and serum NO was greater in group II than in group I, and also greater in group III than in group II. Conclusions: NO appears to play an important and rather complex role in the immuno-inflammatory process and in the remodeling and maintenance of osseous structures. It is therefore logical that modulation of this mediator has potential for the treatment of a number of inflammatory conditions including periodontal disease.

• Journal of the Korean Society of Safety
• /
• v.35 no.3
• /
• pp.96-104
• /
• 2020

The numerical simulations were conducted to investigate the thermal-fluid phenomena occurred inside the experimental apparatus during a PCCS, used to remove heat released in accidents from a containment of light water nuclear power plant, operation. Numerical simulations of the flow and heat transfer caused by wall condensation inside the containment simulation vessel (CSV), which equipped with 18 vertical heat exchanger tubes, were conducted using the commercial computational fluid dynamics (CFD) software ANSYS-CFX. Shear stress transport (SST) and the wall condensation model were used for turbulence closure and wall condensation, respectively. The simulation using the actual size of the apparatus. However, rather than simulating the whole experimental apparatus in consideration of the experimental cases, calculation resources, and calculation time, the simulation model was prepared only in CSV. Selective simulation was conducted to verify the effects of non-condensable gas(NC gas) concentration, CSV internal pressure, and wall sub-cooling conditions. First, as a result of the internal flow of CSV, it was observed that downward flow due to condensation occurred surface of the vertical tube and upward flow occurred in the distant place. Natural convection occurred actively around the heat exchanger tube. Due to this rising and falling internal flow, natural circulation occurred actively around the heat exchanger tubes. Next, in order to check the performance of built-in condensation model using according to the non-condensable gas concentration, CSV internal flow and wall sub-cooling, the heat flux values were compared with the experimental results. On average, the results were underestimated with and error of about 25%. In addition, the influence of CSV internal pressure and wall sub-cooling was small, but when the condensate was highly generated due to the low non-condensable gas concentration, the error was large compared to the experimental values. This is considered to be due to the nature of the condensation model of the CFX code. However, in spite of the limitations of CFD, it is valid to use the built-in condensation model of CFD for PCCS performance prediction from a conservative perspective.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.2
• /
• pp.46-52
• /
• 2017

Recently durability design based on deterministic or probabilistic method has been attempted since service life evaluation in RC(Reinforced Concrete) structure exposed to chloride attack is important. The deterministic durability design contains a reasonable method with time effect on surface chloride content and diffusion coefficient, however the probabilistic design procedure has no consideration of time effect on both. In the paper, a technique on PDF(Probability of Durability Failure) evaluation is proposed considering time effect on diffusion and surface chloride content through equivalent surface chloride content which has same induced chloride content within a given period and cover depth. With varying period to built-up from 10 to 30 years and maximum surface chloride content from $5.0kg/m^3$ to $10.0kg/m^3$, the changing PDF and the related service life are derived. The proposed method can be reasonably applied to actual durability design with preventing conservative design parameters and considering the same analysis conditions of the deterministic method.

• Restorative Dentistry and Endodontics
• /
• v.42 no.4
• /
• pp.309-315
• /
• 2017

Objectives: This study assessed the effect of water storage on the flexural strength (FS) of low shrinkage composites. Materials and Methods: A total of 165 bar-shaped specimens ($2{\times}2{\times}25mm$) were fabricated of 2 low shrinkage composites (Filtek P90 [3M ESPE], GC Kalore [GC International]) and a conventional methacrylate-based composite (Filtek Z250 [3M ESPE]). The specimens were subjected to 3-point bending test at 6 time intervals, namely: immediately after curing, at 24 hours, 1 week, 1 month, 6 months, and 1 year following storage in wet and dry conditions. The FS of the specimens were measured by applying compressive load at a crosshead speed of 1.0 mm/min. Data was analyzed using 3-way analysis of variance (ANOVA) and Tukey's test. Results: Three-way ANOVA revealed significant interactions between time, type of composite, and storage condition (p = 0.001). Tukey's multiple comparison test revealed significant reductions in FS of all composites after 6 months and 1 year of storage in distilled water compared to dry condition. Conclusions: Filtek P90 showed the highest and GC Kalore showed the lowest FS after 1 year storage in distilled water. The immediate high strength of Filtek Z250 significantly decreased at 1 year and its final value was lower than that of Filtek P90.

• Tuberculosis and Respiratory Diseases
• /
• v.62 no.3
• /
• pp.223-226
• /
• 2007

Tetrafluoroethylene is a colorless gas that can be used to synthesize a variety of fluoride compounds by polymerization (e.g., Teflon). Fluoride compounds have many applications in industry. There are several reports of inhalation injury from the pyrolytic product of fluoride compounds. When the polymer is heated under the conditions of inadequate ventilation, the fumes can cause polymer fume fever or pulmonary edema which manifested as symptoms such as fever, chill, profuse sweating, cough and dyspnea. However there are no reports of a direct lung injury caused by tetrafluoroethylene. We report a case of a 27-year-old male presented with acute lung injury after inhaling concentrated tetrafluoroethylene. He complained of cough and dyspnea after the accidental inhalation of tetrfluoroethylene at his workplace. The symptoms improved without any complications after conservative treatment with oxygen and steroid.

• Korean Business Review
• /
• v.5
• /
• pp.241-274
• /
• 1992

General American English(=A.E.) has conservative elements as well as progressive elements. A.E. and B.E. are languages which have more similarities than differances. In this paper. I studied the process of English progress before the A.E. had come into being, and the historical background and the cahristics of A.E. coming into being. Considering the differences between A.E. and B.E. from spelling, pronunciation, vocabulary and grammar, I can give the outline as follows. A spelling 1. B.E. : au, ou $${\rightarrow}$$A.E. : a, o 2. B.E. : e $${\rightarrow}$$A.E. : i 3. B.E. : $${\ae}$$ oe $${\rightarrow}$$A.E. : e 4. B.E. : our $${\rightarrow}$$A.E. : or 5. B.E. : re $${\rightarrow}$$A.E. : er B. pronunciation 1. B.E. : [e] $${\rightarrow}$$A.E. : [i], [e], $$[\partial]$$ 2. B.E. : [a] $${\rightarrow}$$A.E. : 3. B.E. : [i(:)] $${\rightarrow}$$A.E. : [ai], $$[\partial]$$, $$[{\varepsilon}]$$ 4. B.E. : $$[{\ae}]$$ $${\rightarrow}$$A.E. : [e], [c] 5. B.E. : [ai] $${\rightarrow}$$A.E. : $$[{\ae}]$$, [e] 6. B.E. : [c] $${\rightarrow}$$A.E. : [e], [a], [o] 7. In case of "Vowel+[t]+Vowel", [t] is pronounced into [d] or [r] 8. In case of "-nt", [t] becomes a mute. 9. [t]+[j, l, m, n, r, u, or, w] $${\rightarrow}$$A.E. : [?] (=glottal stop) 10. B.E. : [w] $${\rightarrow}$$A.E. : [hw] 11. B.E. : [Voiceless consonants], [Voiced consonants] $${\leftarrow}$$A.E. : [Voiced consonants], [Voiceless consonants] C. Vocabulary The historical background and geographical conditions of those days caused lots of new compounds and neologies. D. Grammar Though we use "of" to indicate the possessive case of inanimate object, -s genitive is used in A.E. In the perfect tense, "have" is often omitted and also auxiliary verb "will" is used in any case

• Journal of Periodontal and Implant Science
• /
• v.40 no.3
• /
• pp.111-118
• /
• 2010

Purpose: The aim of this study was to investigate whether vitrification in the cryopreservation of periodontal ligament (PDL) cells could be useful for tooth banking. Methods: In step 1, primary cultured human PDL cells were cryopreserved in 100% conventional cryopreservation media and 100% vitrification media (ESF40 media) in different temperatures for 2 weeks. In step 2, a series of modified vitrification formulae named T1 (75% vitrification media + 25% F-media), T2 (50% vitrification media + 50% F-media) and T3 (25% vitrification media + 75% F-media) were used to store PDL cells for 2 weeks and 4 weeks in liquid nitrogen. MTT assay was performed to examine the viability of PDL cells. Results: Maximum cell viability was achieved in cells stored in 100% conventional cryopreservation media at $-196^{\circ}C$ (positive control group) in step 1. Compared to the positive control group, viability of the cells stored in 100% vitrification media was very low as 10% in all test conditions. In step 2, as the percentage of vitrification media decreased, the cell viability increased in cells stored for 2 weeks. In 4-week storage of cells in step 2, higher cell viability was observed in the T2 group than the other vitrification formulae while the positive control group had the highest viability. There was no statistically significant difference in the cell viability of 2-week and 4-week stored cells in the T2 group. Conclusions: These observations indicate 100% vitrification media is not successful in PDL cell cryopreservation. Conventional cryopreservation media is currently the most appropriate media type for this purpose while T2 media would be interesting to test for long-term storage of PDL cells.

• International Journal of Highway Engineering
• /
• v.13 no.2
• /
• pp.167-174
• /
• 2011

This research was conducted to propose the design methodologies of post-tensioned concrete pavements (PTCPs) for specialized section pavements. The specialized sections considered in this study included bus stop sections in urban bus-only lanes and culvert existing highway sections that often showed severe failures. The PTCP designs of those specialized sections were performed based on both the stresses and the fatigue failures, and more conservative design results were selected. In the stress based design, the maximum tensile stress under extreme load conditions was obtained using finite element analyses first. Then, the number of tendons and the tendon spacing were determined so that the tensile stress was less than the allowable flexural strength. The AASHTO fatigue failure equations were used in the fatigue failure based design. From this study, the design methodologies of PTCP for bus stop sections in bus-only lanes and culvert existing highway sections were successfully suggested.

• Journal of Trauma and Injury
• /
• v.31 no.1
• /
• pp.1-5
• /
• 2018

Purpose: Although there has been substantial progress for the treatment of thoracic trauma, the mortality of the penetrating neck injury is still high, has been reported about 10-15%. However, there has not been a report which is reflecting Korean medical present. We retrospectively analyzed the penetrating neck injury patients based on the Korean Trauma Data Base. Methods: Between December 2013 and June 2017 at the trauma center of the Pusan National University Hospital, Busan, Korea, total of 36 patients with isolated low-velocity penetrating neck injuries were included. We analyzed the patients' age, gender, injury mechanism and causes by medical chart review. Results: Among total of 36 patients, 26 (72.2%) were male and 10 (27.8%) were female. Homicidal neck injuries were most common, followed by accidental and suicidal injuries (47% vs. 33% vs. 19%, respectively). All penetrating injuries in our study were low-velocity trauma such as following: knife (n=16, 44.4%); glass or glass bottle (n=11, 30.6%); scissors (n=4, 11.1%); grinder (n=2, 5.6%); and three (8.3%) of miscellaneous injuries. Twenty-seven (75.0%) patients underwent emergency surgery, and only one (2.8%) patient underwent elective surgery. Eleven (30.6) patients were diagnosed with superficial injuries, including six patients who had conservative treatment. Twelve (33.3%) patients had arterial injuries and 10 (27.8%) patients had venous injuries. The patients who had deep injuries showed significant difference against the patient with superficial injury (98.0 vs. 129.1, p=0.008). Conclusions: Low velocity penetrating injury confined to the neck is able to be successfully treated with prompt surgical management. Regardless of the conditions which are evaluated at emergency department, all penetrating neck injury patients should be regarded as urgent surgical candidates.

• The Journal of the Korean dental association
• /
• v.49 no.4
• /
• pp.219-226
• /
• 2011

Snoring and obstructive sleep apnea (OSA) are common sleep disordered breathing conditions. Habitual snoring is caused by a vibration of soft tissue of upper airway while breath in sleeping, and obstructive sleep apnea is caused by the repeated obstructions of airflow for a sleeping, specially airflow of pharynx. Researchers have shown that snoring is the most important symptom connected with the obstructive sleep apnea syndrome The treatment is directed toward improving the air flow by various surgical and nonsurgical methods. The current surgical procedures used are uvulopalatopharyngoplasty(UPPP), orthognathic surgery, nasal cavity surgery. Among the nonsurgical methods there are nasal continuous positive air pressure(CPAP), pharmacologic therapy. weight loss in obese patient, oral appliance(sleep splint). Sleep splint brings the mandible forward in order to increase upper airway volume and prevents total upper airway collapse during sleep. However, the precise mechanism of action is not yet completely understood, especially aerodynamic factor. The aim of this study evaluated the effect of conservative treatment of snoring and OSAS by sleep splint through measured aerodynamic change by an aerophone II. We measured a airflow, sound pressure level, duration, mean power from overall airflow by aerophone II mask. The results indicated that on a positive correlation between a decrease in maximum airflow rate and a decrease in maximum sound pressure level, on a negative correlation between a decrease in maximum airflow rate and a increase in duration.