• Archives of design research
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• v.18 no.2 s.60
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• pp.155-164
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• 2005

Home-service robots need to have sufficient spatial information about the surroundings for interacting with human intelligently and performing services efficiently. It is very important to investigate the efficient interaction style that supports map building task through human-robot collaboration. We first analyzed map building task with a cleaning robot and drew 4 design factors and tentative solutions, including map building procedure (task-preferred procedure/space- preferred procedure), LCD display installation (robot/robot+remote control), navigation method (push type/pull type), feedback modality(GUI/GUI+TTS). The design factors and tentative solutions were defined as independent variables and levels. This research investigated how those variables affect to the human task performance and behavior in map building tast. 8 kinds of experiment prototypes were built and usability test among 16 house wives was conducted for acquiring empirical data. As the experiment result, in terms of map building procedure, space-preferred procedure indicated better task performance than task-proffered procedure as we expected. For the LCD display installation factor, remote control with LCD display indicated higher task performance and subjective satisfaction. In robot navigation method, it was very difficult to find a significant difference between push type and pull type which contrary to our expectation. In fact, push type indicated higher subjective satisfaction. Also in feedback modality, we have acquired negative feedback an additional TTS operation guidance. It seems that robot's autonomy before achieving spatial information is rudiment condition which means users are just interacting with a mobile appliance. Thus they prefer remote-control-based interaction style in robot map building process as they used in traditional appliance control.

• Clinics in Shoulder and Elbow
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• v.13 no.1
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• pp.72-78
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• 2010

Purpose: Too develop a flexible drill device that can be inserted into the shoulder joint so that arthroscopic transosseous suture repair for Bankart lesion is possible. Materials and Methods: We created a device composed of a flexible drill unit and a guide pipe unit. The flexible drill unit was made of flexible multifilament wires (1.2 mm in diameter) that was twisted into one cord so that it can flex in any direction and a drill bit (1.2 mm in diameter) that is attached onto one end of the flexible wire. The guide pipe unit was a 150 mm long metal pipe (2.0 mm in inner diameter and 3.0 mm in outer diameter), with one end bent to 30 degrees. The flexible drill set was inserted into the shoulder joint through the posterior portal of the joint. The guide pipe component was placed onto the medial wall of the glenoid so that the pipe was placed 5 mm posterior to the margin of the anterior glenoid rim. The flexible drill was driven through the glenoid by the power drill so that holes were made in the glenoid. A non- absorbable suture was passed through the hole. Tying of a sliding knot tying was accomplished over the capsule and labrum after making a stitch through the capsule and labrum with a suture hook loaded with suture passer. The same procedures were done at the 2 and 4 O'Clock positions of the glenoid. Results: Five cases with Bankart lesion received arthroscopic transosseous repair with our flexible drill device. There were no intraoperative problems. Neither redislocation nor subluxation was reported at final follow-up. Conclusion: Arthroscopic transosseous suture repair without suture anchors and easy tying of a sliding knot are possible with a flexible drill set.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.1
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• pp.87-95
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• 2015

Purpose : This study presents the usefulness assessment of secondary shield for the lens exposure dose reduction during radiation treatment of peripheral orbit. Materials and Methods : We accomplished IMRT treatment plan similar with a real one through the computed treatment planning system after CT simulation using human phantom. For the secondary shield, we used Pb plate (thickness 3mm, diameter 25mm) and 3 mm tungsten eye-shield block. And we compared lens dose using OSLD between on TPS and on simulation. Also, we irradiated 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$) on a 5cm acrylic phantom using the secondary shielding material of same condition, 3mm Pb and tungsten eye-shield block. And we carried out the same experiment using 8cm Pb block to limit effect of leakage & transmitted radiation out of irradiation field. We attached OSLD with a 1cm away from the field at the side of phantom and applied a 3mm bolus equivalent to the thickness of eyelid. Results : Using human phantom, the Lens dose on IMRT treatment plan is 315.9cGy and the real measurement value is 216.7cGy. And after secondary shield using 3mm Pb plate and tungsten eye-shield block, each lens dose is 234.3, 224.1 cGy. The result of a experiment using acrylic phantom, each value is 5.24, 5.42 and 5.39 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Applying O.S.B out of the field, each value is 1.79, 2.00 and 2.02 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Conclusion : When secondary shielding material is used to protect critical organ while irradiating photon, high atomic number material (like metal) that is near by critical organ can be cause of dose increase according to treatment region and beam direction because head leakage and collimator & MLC transmitted radiation are exist even if it's out of the field. The attempt of secondary shield for the decrease of exposure dose was meaningful, but untested attempt can have a reverse effect. So, a preliminary inspection through Q.A must be necessary.

• Korean Journal of Weed Science
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• v.16 no.2
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• pp.81-87
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• 1996

Seeds of rice, cv. Ilpoom, and barnyardgrasses(Echinochloa crus-galli, vars. oryzicola, crux-galli, and praticola) were sown for a characterization of their responses to temperature during emergence under a dry direct-seeded condition. A laboratory-made aluminum block apparatus for emergence-temperature control conferred a linear continuous temperature gradient from 10 to $30^{\circ}C$ to the seeds from cooling to heating ends of the apparatus. The lowest temperature for emergence was $12.3^{\circ}C$ for rice cv. Ilpoom, and $11.0^{\circ}C$ for the three varieties of Echinochloa spp.. Percent emergence of rice increased sharply with an increase in temperature by ca. $20^{\circ}C$, then leveled-off, while those of barnyardgrasses increased almost linearly with temperatures up to $30^{\circ}C$. In rice the time required for emergence after seeding was shortened exponentially with increased temperature while those for barnyardgrasses were shortened almost linearly from 11 to $30^{\circ}C$. The temperature-response characteristic of rice in emergence-speed was almost the same among those for the 1st emergence, emergence by 25, 50, 75%, or average emergence time. At $13^{\circ}C$, $346.7^{\circ}C$ days of accummulated temperature(26.67 days) were required for the 1st emergence in rice while 131.7, 136.0, and $138.7^{\circ}C$ days(10.13, 10.46, and 10.67 days) were required for the 1st emergence in E. spp., vars. crus-galli, praticola, and oryzicola, respectively. Greater cold tolerance and increasingly faster emergence of barnyardgrasses than rice below $20^{\circ}C$ seem to render the barnyardgrasses as much more competitive than rice at lower temperatures.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.8-15
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• 2011

Purpose: This study evaluated the bonding strength of direct relining resin to Co-Cr denture base material according to surface treatment and immersion time. Materials and methods: In this study, Co-Cr alloy was used in hexagon shape. Each specimen was cut in flat surface, and sandblasted with $110\;{\mu}m$ $Al_2O_3$ for 1 minute. 54 specimens were divided into 3 groups; group A-control group, group B-applied with surface primer A, group C-applied with surface primer B. Self curing direct resin was used for this study. Each group was subdivided into another 3 groups according to the immersion time. After the wetting storage, shear bond strength of the specimens were measured with universal testing machine. The data were analyzed using two-way analysis of variance and Tukey post hoc method. Results: In experiment of sandblasting specimens, surface roughness of the alloy was the highest after 1 minute sandblasting. In experiment of testing shear bond strength, bonding strength was lowered on group B, C, A. There were significant differences between 3 groups. According to period, Bonding strength was the highest on 0 week storage group, and the weakest on 2 week storage group. But there were no significant differences between 3 periods. According to group and period, bonding strength of all group were lowered according to immersion time but there were no significant differences on group B and group C, but there was significant difference according to immersion time on group A. Conclusion: It is useful to sandblast and adopt metal primers when relining Co-Cr metal base dentures in chair-side.

• The Korean Journal of Malacology
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• v.19 no.2
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• pp.133-142
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• 2003

For the effective seedling production of flat oyster, Ostrea denselamellosa, dietary value of live food, densities, water temperature and salinity on growth and survival rate of the larvae were examined. In rearing larvae by feeding them phytoplankton diets, the optimal survival rate and growth rate of larvae were found using a mixed phytoplankton diet which was mixed with Isochrysis galbana, Chaetoceros calcitrans and Chlorella sp. The highest growth and survival rates of the larvae were 208.4% and 38.8% with the phytoplankton diet. In growth and survival rates of larvae with various rearing densities, the highest survival and growth rates were 228.1% and 29.0% at the density of 2 individuals/ml. In observing rearing experiments of the flat oyster larvae under various temperature conditions, average growth rates of the larvae in respect to shell length were 202.2%, 240.4%, 250.6% and 121.3% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32 $^{\circ}C$, respectively. And average survival rates of the larvae were 16.0%, 32.0%, 13.0% and 0% in natural water temperatures (18-22$^{\circ}C$), 24$^{\circ}C$, 28$^{\circ}C$ and 32$^{\circ}C$, respectively. In rearing at various salinities, the highest growth rates of the larvae in shell length was 240.0% at 30.0 psu and the highest survival rate was 31.0% at 25 psu.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.30-36
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• 2012

This study was conducted to evaluate the microbiological hazard on nursery school children's hands and to investigate the reduction effect of hand washing education. A total of 59 nursery school children's hands were tested. The average number of total aerobic bacteria was $3.72{\pm}0.38log\;CFU/hand$. Five children's hands(2 male and 3 female) were positive(14.3%) for the coliform bacteria. These results showed that hand washing education are required repetitively. Among the pathogenic bacteria tested in this study, $Staphylococcus$ aureus and $Bacillus$ $cereus$ were detected in 9(25.7%) and 16(45.7%) out of 35 their hands, respectively. Twelve out of sixteen $B.$ $cereus$ isolates(70.0%) produced enterotoxin. The results indicate that the hand hygiene of nursery school children needs to be improved. Comparing before and after hand washing in educated and non-educated group, the reduction effect of total aerobic bacteria on their hands was 0.42 and 0.60 log CFU/hand, respectively. The educated group showed 0.18 log CFU/hand higher reduction effect than non-educated group but microorganism did not eliminate perfectly. From the results, using a hand sanitizer after washing with soap and the continuous hand washing education are required to control the contaminated bacteria on nursery school children's hands.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.65-65
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• 2018

갈바륨 도금강판은 알루미늄의 우수한 차폐 특성과 내열성, 열 반사성을 가지며 아연의 희생방식 특성을 겸비하여 동일 부착량의 용융 아연도금 및 알루미늄 도금강판에 비해 우수한 내식성을 나타낸다고 알려져 있다. 또한 이것은 표면이 미려하고 경제성이 높아 건자재 용도로 현재까지도 세계적으로 널리 이용되고 있다. 여기서 지칭하는 바륨 도금강판(galvalume steel)은 아연과 알루미늄 도금강판의 장점을 접목하기 위해 55 Al-43.4 Zn-1.6 Si (wt.%)로 구성되어 개발된 3원계 성분의 합금도금강판이다. 한편, 최근에는 강재의 내식성을 향상시키기 위한 다양한 연구 결과에 의해 Zn-Al-Mg의 3원계 합금도금강판도 개발되어 사용되고 있다. 이것은 기존의 아연도금 강판 보다 10배 정도의 우수한 내식성을 나타내는 것으로 보고되고 있다. 특히, 이것은 도금된 평판부의 내식성은 물론 절단된 도금 단면부의 내식성도 매우 우수하다고 알려져 있다. 그러나 상기한 갈바륨 도금강판의 경우에는 도금된 표면부에 비해 단면부의 내식성이 상대적으로 취약한 것으로 알려져 있다. 따라서 본 연구에서는 갈바륨 도금강판의 내식성을 종합적으로 향상시키기 위하여 이 갈바륨 도금강판 상에 PVD 스퍼터링법에 의해 Mg 코팅막의 제작을 시도하였다. 여기서 Mg 코팅막은 후처리 된 갈바륨 도금강판 상에 Ar 공정압력 2 및 20 mTorr 조건 중 1.5 및 $3{\mu}m$ 두께로 제작하였다. 또한 제작한 코팅막에 대해서는 모폴로지 관찰(SEM) 및 결정구조 분석(XRD)을 하였고, 분극측정, 염수분무 시험(SST) 및 복합부식 시험(CCT)에 의해 표면 및 단면부의 내식성평가를 수행하였다. 또한 여기서는 염수분무 및 복합부식 시험 후의 시험편도 채취 하여 표면 및 단면부위에 대한 원소조성 분석(EPMA)과 결정구조 분석(XRD)을 실시하였다. 이상의 실험 결과에 의하면, 본 실험에서 제작한 Mg 코팅막은 그 두께가 두꺼울수록 표면 Mg 결정립의 크기가 증가하였고, 그 부식속도가 증가하는 경향을 나타내었다. 또한 여기서는 공정압력이 높은 조건에서 제작한 막일수록 Mg(002)면 피크 강도가 감소하고 Mg(101)면 피크의 배향성이 증가하였다. 그때 그 막의 내식성은 향상되는 경향을 나타내었다. 그리고 종합적으로 염수분무 및 복합부식 시험 결과에 의하면 Mg이 코팅된 갈바륨 도금강판은 기존 갈바륨 도금강판 보다 내식성이 현저히 향상되었다. 특히, 단면부 내식성의 경우에는 기존 대비 5배 이상 향상되는 경향을 나타내었다. 여기서 단면부 내식특성 분석을 위한 EPMA 원소조성 분석 결과에 의거하면, 부식 초기에는 마그네슘의 부식생성물에 의해 단면부가 치밀하게 보호되고 있음을 확인할 수 있었다. 그 이후에는 부식이 지속적으로 진행됨에 따라 갈바륨 도금층에서 용출된 알루미늄 및 아연 성분이 마그네슘과 함께 치밀한 부식생성물을 형성하여 단면부를 차폐함에 따라 단면부의 내식성이 크게 향상된 것으로 생각된다. 이러한 부식생성물의 결정구조 분석 결과에 따르면, 염수분무와 복합부식 시험에서는 공통적으로 MgO, $Mg(OH)_2$ 이외에도 Simonkolleite상 등이 형성되었다. 또한 건-습 반복 부식시험인 복합부식시험 후에는 $Mg_5(CO_3)_4(OH)_24H_2O$(Hydromagnesite)상 등이 형성됨을 확인할 수 있었다. 즉, 본 실험에서 후처리된 갈바륨 도금강판 상에 제작한 마그네슘 코팅막의 경우에는 상기와 같은 다양한 부식반응에 의해 표면 및 단면부에 형성된 Mg계 부식생성물과 $Zn_5(OH)_8Cl_2H_2O$(Simonkolleite)상에 의해서 표면은 물론 단면부 내식성이 크게 향상된 것으로 사료된다.

• Journal of dental hygiene science
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• v.16 no.2
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• pp.176-182
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• 2016

The purpose of this study was to evaluate the in-vitro efficacy of the active ingredients of dentifrice following treatment time. The whitening effect was evaluated by a change in lightness value relative to the contact time of hydrogen peroxide, by using artificially stained hydroxyapatite discs. The anti-calculus effect was assessed based on the amount of calcium eluted from the human dental calculus by sodium pyrophosphate. Remineralization was evaluated by the Vickers hardness test following the application of sodium fluoride to bovine enamel. In order to view dentinal tubules occlusion, the formation of insoluble calcium salts by bovine dentin specimens was observed using scanning electron microscopy. Change in lightness value (${\Delta}L$) was $5.50{\pm}1.51$ after 1 min of treatment, $5.73{\pm}0.43$ after 3 min, $8.64{\pm}0.24$ after 10 min, $18.93{\pm}0.76$ after 30 min, and $27.35{\pm}0.54$ after 60 min. The amount of calcium eluted from the human dental calculus was $4.23{\pm}0.14ppm$ after 1 min of treatment, $4.51{\pm}0.04ppm$ after 3 min, $12.12{\pm}0.16ppm$ after 10 min, $17.85{\pm}0.81ppm$ after 30 min, and $25.15{\pm}0.32ppm$ after 60 min. The Vickers hardness change value (${\Delta}VHN$) was $1.96{\pm}1.44$ after 1 min, $1.52{\pm}1.06$ after 3 min, $9.06{\pm}0.15$ after 10 min, $10.83{\pm}5.13$ after 30 min, and $12.55{\pm}2.09$ after 60 min. Partial dentinal tubules occlusion was observed at 10 min and complete occlusion was evident at 60 min. In summary, the use of patch type dentifrices for 10, 30, or 60 min were 1.57 to 8.26 times more effective than using the paste type dentifrices for 1 to 3 min. Based on these findings, it is reasonable to expect that the use of patch type dentifrices for 10 min would lead to remineralization, anti-calculus and dentinal tubules occlusion effects, and that use for 30 min would result in a whitening effect.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.1
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• pp.55-60
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• 2010

Purpose: The shrinkage of dental resin cement may cause several clinical problems such as distortion that may jeopardize the accurate fit to the prepared tooth and internal stress within the restorations. It is important to know the polymerization shrinkage-strain of dental resin cement to reduce clinical complications. The purpose of this study was to investigate the polymerization shrinkage-strain kinetics of six commercially available dental resin cements. Material and methods: Three self-cure resin cements (Fujicem, Superbond, M-bond) and three dual-cure resin cements (Maxcem, Panavia-F, Variolink II) were investigated. Time dependent polymerization shrinkage-strain kinetics of the materials were measured by the Bonded-disk method as a function of time at $23^{\circ}C$, with values particularly noted at 1, 5, 10, 30, 60, 120 min after mixing. Five recordings were taken for each materials. The data were analyzed with one-way ANOVA and Scheffe post hoc test at the significance level of 0.05. Results: Polymerization shrinkage-strain values were 3.72%, 4.19%, 4.13%, 2.44%, 7.57%, 2.90% for Fujicem, Maxcem, M bond, Panavia F, Superbond, Variolink II, respectively at 120 minutes after the start of mixing. Panavia F exhibited maximum polymerization shrinkage-strain values, but Superbond showed minimum polymerization shrinkage-strain values among the investigated materials (P < .05). There was no significant differences of shrinkage-strain value between Maxcem and M bond at 120 minutes after the start of mixing (P > .05). Most shrinkage of the resin cement materials investigated occurred in the first 30 minutes after the start of mixing. Conclusion: The onset of polymerization shrinkage of self-cure resin cements was slower than that of dual-cure resin cements after mixing, but the net shrinkage strain values of self-cure resin cements was higher than that of dual-cure resin cements at 120 minutes after mixing. Most shrinkage of the dental resin cements occurred in the first 30 minutes after mixing.