• Tunnel and Underground Space
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• v.25 no.2
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• pp.125-132
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• 2015

As for noise and vibration occurring due to construction near fish farms, engineering and the technical opinions of experts in different areas were excluded in calculating any damage. The victims tend to present only biological consulting-based opinions while construction companies tend to present information on general construction noise and vibration as they have little biological knowledge on fish. So, the National Environmental Dispute Medication Commission presented specific damage standard in 2009 through studies on standard in calculating compensation and damage assessment of farm-raised fish that were affected by noise and vibration. Currently, 140 dB re $1{\mu}Pa$ is accepted as damage standard of underwater noise in the country. This standard is the RMS value of continuous sounds for more than a second, not the impulsive sounds. To look up the data on existing studies, fish showed different reactions to underwater sounds according to the different kinds of fish such as ostariophysan or non-ostariophysan, and pinnipeds or non-pinnipeds. So, this study will present damage standards for impulsive sounds in consideration of the differences in the characteristics of the impulsive and continuous sounds.

• The Journal of Engineering Geology
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• v.5 no.1
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• pp.1-20
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• 1995

A train overturn accident occurred on March 1993 in the Gupo area, northern part of Pusan, unfortunately had taken a heavy toll of lives and caused a great loss of property as well. The reasons for the subsidence of the basement under the railroads, which presumed to be the main cause of the accident, have been investigated from many different angles, including conventional geotechnical investigation methods. The deduced nuin reasons of the subsidence were: 1. blasting for tunnel excavation (NATM) at about 39 meter under the railroads, and 2. unexpected change of bedrock conditions along the direction of tunnel. But this accident was derived nrranlv from the lack of geological and geotechnical information under railroad area because it was impossible to drill beneath the railroads. This paper introduces a new geophysical survey techniqueseisrnic geotomography, and shows some results of the method applying to investigate the underground structure of the accident area. This method not only overcomes the unfavourable environment which many conventional investigation methods cannot face, but produces an image of underground structure with high resolution. Furthermore, the outputs from geotomogaphic analysis could provide very valuable in-situ basic parameters (like seismic velocities, elastic moduli, etc.) which is essential to the design and construction.

• Journal of Bio-Environment Control
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• v.10 no.2
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• pp.75-79
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• 2001

Stem firmness and flowering response of cut lily as influenced by medium composition (Control; Upland soil, Pt; Peatmoss, Pe; Perilite, Ve; Vermiculite, Rrh; Rotted rice-hull, RPt: Russian Peatmoss) were studied. For 'Casa Blanca', plant height and length of flower stalk increased when bulbs were planted in Pt:Rrh:Ve (1:1:1, v.v$^{-1}$ ), and dried leaves of lower part plants decreased in RPt:Pe:Rrh (1:1:1, v.v$^{-1}$ ). In case of 'Marco Polo', plant height and length of lower stalk increased in Pt:Rrh (1:1, v.v$^{-1}$ ) as compared to other treatment, number of leaves and dried leaves increased when bulbs were planted in RPt:Pe:Rrh (1:1:1, v.v$^{-1}$ ) as compared to the control. Flowering of 'Casa Blanca' increased in RPt:Pe:Rrh (1:1:1, v.v$^{-1}$ ) as compared to the control and that o 'Marco Polo' increased when bulbs planted in Pt:Rrh(1:1, v.v$^{-1}$ ). Flower-bud blasting of both cultivars increased with Pt as compared. Stem firmness of 'Casa Blanca' increased in Pt:Pe:Ve (1:1:1, v.v$^{-1}$ ), and especially stem firmness of upper part plant of 'Marco Polo' increased in Pt:Rrh (1:1, v.v$^{-1}$ ) as compared to the control. Generally, stem firmness of 'Casa Blanca' was not influenced by the culture medium.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.3
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• pp.221-230
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• 2006

Recently, the need for esthetic results has increased the interest for all-ceramic crown prosthesis. Furthermore, the development of zirconium core via CAD/CAM system has allowed the all ceramic restorations to be applied to almost all fixed prosthesis situations. But, the increased strength has been reported to increase in proportion with the bond strength of cement, and recently, the tribochemical system which increases the bond strength through, silica coating and silanization has been introduced. The purpose of this study was to compare the $Rocatec^{TM}$ system and $CoJet^{TM}$ system with the traditional acid etching and silanization method of the irconium based ceramic. The surface character was observed via SEM(X2000), and the bond strength with the resin cement were measured. 50 In-Ceram Zirconia (Adens, Korea) discs were fabricated and embedded in resin, group 1 was treated with glass-bead blasting and cleaning, group 2 was treated with 20% HF for 10 minutes and silanized, group 3 was treated with the $Rocatec^{TM}$ system, and group 4 was treated with the $CoJet^{TM}$ system. Each group was comprised of 10 specimens. The specimens were cemented to a $3mm{\times}5mm$ resin block with Super-Bond C&B. The shear bond strength was measured with the $Instron^{(R)}$ 8871 at a crosshead speed of 0.5mm/min. The results were as follows. 1. According to SEM results, there were little difference between group 1 & group 2, but in group 3 and 4, silica coating was detected and there was increase in surface roughness. 2. The shear bond strength decreased in the order of group 3(46.28MPa), group 4(42.04MPa), group 2(31.56MPa), and group 1(27.46MPa). 3. There was significant differnce between group 1&2 and group 3&4(p<0.05). From the results above, it can be considered that the conventional method of acid etching and silane treatment cannot increase the bond strength with resin cements, and that by applying the tribochemical system of $Rocatec^{TM}$ system and $CoJet^{TM}$ system, we can achieve a stronger all ceramic restoration. Further studies on surface treatments to increase the bond strength are thought to be needed.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.327-336
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• 2007

Purpose This study was planned to compare and evaluate the stability of implant using $Osstell^{TM}$ and Osstell $Mentor^{TM}$. Material and methods Artificial bone and RBM(resorbable blasting media) surface blasted implants(Osstem US II, SS II implants - diameter: 4mm, length: 13mm) were used. To measure the stability of installed implants, $Osstell^{TM}$ and Osstell $Mentor^{TM}$ were used. In the first experiment, five implants were installed in D1(external type implants) and D3(internal type implants). In the second experiment, 4 internal type implants were divided in two groups and installed in D1 artificial bone with different depth. In the third experiment, two external implants were installed in D1 and D3 artificial bone each and two internal implants were installed in D1 and D3 artificial bone. In all groups, their stability were measured by $Osstell^{TM}$ and Osstell $Mentor^{TM}$. Results In all groups, $Osstell^{TM}$ and Osstell $Mentor^{TM}$ both showed reliable measurement values. The value difference between $Osstell^{TM}$ and Osstell $Mentor^{TM}$ was observed but the difference was small and clinically acceptable. Conclusion These results suggest that the use of Osstell $Mentor^{TM}$ has clinical relevance in the assessment of implant stability.

• Geophysics and Geophysical Exploration
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• v.16 no.1
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• pp.53-58
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• 2013

It was introduced a seismic mini-array that could monitor microseismicity efficiently and analyzed seismic data obtained from the mini-array that was operated from December 19, 2012 to January 9, 2013. The mini-array consisted of a six channel data logger, a central 3 components seismometer, and a tripartite array of vertical sensors centered around the 3 components seismometer as an equilateral triangle with about 100 m aperture. All seismometers that had the same instrument response were connected a 6 channel data logger, which was set to record seismograms at a sampling rate of 200 sps. During the three weeks of campaign, a total of 16 microearthquakes were detected. Using time differences of P wave arrivals from the vertical components, S-P time from 3 components seismometers, and back azimuth from the seismic array analysis, it was possible to locate the hypocenter of the microearthquake even with one seismic miniarray. The epicenters of two nearest microearthquakes were a quarry site located 1.3 km from the mini-array. The records of quarry blasting confirmed the our analysis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.4
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• pp.291-299
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• 2005

Objectives : It is well known that cigarette smoking is harzardous to the osseointegration of dental implant, due to the impaired wound healing accompanied by reduced alveolar bone density. The aim of this study is to evaluate the influence of cigarette smoke on the implant osseointegration by the time factor consideration. Materials and methods : Twenty-four male Spraque-Dawley rats (8 weeks, weighting 200 to 250g) were used in this study. In the experimental group, 13 rats were exposed to cigarette smoke, 8 minutes per day during 6 weeks, and 12 rats in the control group were not exposed at any time. RBM (Resorbed blasting media) surfaced implant (diameter 3.3mm, length 5.0mm, AVANA Co., Korea) was placed in the right femur of each rat. Each implant with surrounding bone was prepared with microtome (cutting band 0.2mm$^{(R)}$, EXAKT Co., Germany) after 1 day, 2, 4, 8 and 12 weeks and stained with toluidine blue (1%). Another clinical investigation of each implant was also done at each evaluation time. Results : Clinical investigation around implant fixture showed that there were no significant differences between the control and experimental group. Microscopic observation around implant fixture showed that there were significant differences between the control and experimental group at the initial stage after implant fixture installation. Experimental group showed a decreased bone to implant contact within 4 weeks compared to control group, but showed similar characteristics after 4 weeks. Conclusion : Smoking inhalation effect on the dental implant showed the impaired wound healing by vasoconstriction and decreased intramedullary blood flow at initial stage of osseointegration. This experimental results can be clinically useful to the implant surgery of smoking patients.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.71-83
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• 2001

The purpose of this study was to compare the effects of various surface treatments by measuring removal torque on bone healing around titanium implants. 40 Screw-shaped cp titanium implants with length of 4mm, outer diameter of 3.75mm, and pitch-height of 0.5mm were used Group 1 was left as machined(control), Group 2 was blasted with $50{\mu}m\;Al_2O_3$, group 3 was blasted and etched in etching solution($NH_4OH : H_2O_2:H_2O= 1 : 1 : 5$) at $90^{\circ}C$ for 1 minute group 4 was blasted and oxidated under pure oxygen at $800^{\circ}C$. The implant surface roughness was analyzed with SEM and CLSM(Confocal Laser Scanning Microscope) and implants were placed in proximal tibial metaphysis of 10 New Zealand White rabbits. After 3 months of healing period, removal torque of each implant was measured to compare bone healing around implant. The results obtained were as follows 1. In SEM view, blasting increased the roughness of the surface, but etching of that rough surface decreased the roughness due to the removal of the tip of the peak. Oxidation also decreased the roughness due to formation of needle-like oxide grains on the implant surface. 2. The Sa value from CLSM was least in the machined group($0.47{\mu}m$), greatest in blasted group($1.25{\mu}m$), and the value decreased after etching($0.91{\mu}m$) and oxidation($0.94{\mu}m$). 3. The removal torque of etched group(24.5Ncm) was greater than that of machined group(16.7Ncm) (P<0.05), and was greatest in the oxidated group(40.3Ncm) and the blasted group(34.7Ncm).

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.525-536
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• 2005

여러 연구들을 통해 많은 학자들이 임프란트 안정성(stability)은 표면의 특징에 달려있다고 생각하게 되었다. 표면의 구조, 에너지, 산화물(oxide) 두께와 표면성상(topography)등 임프란트의 표면의 특징은 임프란트와 골조직의 반응에서 중요한 역할을 하는 것이 알려짐에 따라 티타뮨 임프란트의 표면의 처리 방법에 큰 관심을 가지게 되었다. 그 중에서 티타늄 임프란트 표면의 산화피막화(anodization)가 한 방법으로 대두되었다. 이 방법은 전기화학적 방식으로 임프란트 표면에 거칠고(rough)두꺼우며(thick), 기공(pore)을 가지는 산화물 막을 형성하는 것으로 산화물의 두께는 coronal 부분(l-2 ${\mu}m$)으로부터 apical부분(7-10 ${\mu}m$)까지 증가하게 된다. 산화피막의 표면에는 다양한 크기의 수많은 기공이 주로 1-2 ${\mu}m$ 두께로 임프란트의 apical 부분에서 존재하며, 임프란트 표면의 거칠기는 conical 위부분에서 apical 부분까지 계속 증가한다(평균 Ra value=1.2 ${\mu}m$). 또 다른 표면 처리 방법으로는 blasting 후에 etching을 한 SLA 표면이 있다. 이 연구의 목적은 일반적으로 많이 이용되고 있는 anodized 표면과 SLA 표면의 조직학적 반응을 비교 분석하는 것이다. 24개 임프란트를(anodized surfaced implant-12개 , SLA-12개, 8mm ${\times}\;{\Phi}$ 4.3) 6마리 토끼의 오른쪽과 왼쪽 femur에 식립하였다. 12주후에 동물들을 희생하여 EXACT cutting-grinding system을 이용하여 샘플을 절단하고 800, 1200 및 4000 번 연마제(abrasive) paper로 20-50 ${\mu}m$ 까지 grinding하였다. 샘플은 Multiple staining 용액으로 염색하여 SLA 임프란트 군과 비교하였다. 골과 임프란트 사이에 연결을 TDI 프로그램을 이용하여 %로 측정하였다. SLA 임프란트 군 경우에는 골과 임프란트 사이의 연결이 $74{\pm}19%$ 이고, 양극 산화한 임프란트 군 경우에는 $77{\pm}9%$이었다. 양극 산화한 티타늄 임프란트의 골 접촉률이 SLA 표면 임프란트 경우과 통계학적으로 유의한 차이는 보이지 않았다.

• Journal of Periodontal and Implant Science
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• v.37 no.2
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• pp.209-221
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• 2007

Recently, immediately after losing teeth. implant placement has been greatly attempted. Implant can help restoration of tooth functions within short time. This study was an attempt to examine the extent of osseointergation when the implants will be placed immediately after teeth extraction using domestic implant systems. Implants were inserted in beagle dogs and evaluated the clinical, radiological, histological and histomorphometric assay at 6 weeks and 12 weeks. For experimental materals, $STAGE-1^{(R)}$($4.1{\times}8mm$, Lifecore, USA), $SS-III^{(R)}$($4.0{\times}8mm$, OSSTEM, Korea) and $IFI^{(R)}$($4.0{\times}8mm$, Dio, Korea) implants treated with RBM were placed. All the placed site showed normal results without fail and inflammation clinically and radiologically. As a result of measurement by periotest, it showed $-2\;{\sim}\;-5$ and stable status comprehensively. There was no statistically significant difference among implants(p<0.05). Bone tissue adjacent to implant showed increased marrow tissue at 6 weeks. Nevertheless, osteogenic structure was not observed remarkably. In a 12 weeks opinion, bone tissue composed of osseointegration along implant interface showed significantly decreased marrow tissue containing central vessels unlike a 6 weeks opinion and matured compact bone whose osteogenic structure is well formed. BIC were 42.4%, 32.0% and 34.9%, respectively in 6 weeks and there was no statistically significant difference among group(p<0.05). In 12 weeks, BIC were 58.8%, 61.9% and 57.5%. respectively and there was no statistically significant difference among groups(p<0.05). It is considered that all 3 implant systems are suitable for immediate implant placement.