• Journal of Dental Rehabilitation and Applied Science
• /
• v.18 no.2
• /
• pp.81-91
• /
• 2002

Dental implant systems have shown many post-surgical problems and One of the most frequent problem is screw loosening. To reduce screw loosening, a number of methods have been tried and recently fundamental modification of fixture-abutment connection structure was developed and used the most frequently. Former implant system structure, such as Br${\aa}$nemark, had external hex with the height of 0.7 mm and later, fixture with external hex of 1.0 mm height and internal hex structure were developed. In addition, the method of morse taper application was introduced to reduce screw loosening. In this study, the level of screw loosening of each implant systems was compared based on the vibration loosening measurement of abutment screw of each implant systems. Analysis of measured value was performed using 3 kinds of methods, (i) Percentage of average of initial 3 times loosening-torque value(initial loosening value) to tightening-torque of 30 Ncm, (ii) Percentage of loosening-torque value after 200 N strength loaded(experimental value) to initial loosening value and (iii) Percentage of experimental value to 30 Ncm of tightening-torque. Each result of analyses shows the value of initial loosening, loosening by repetitive load and final loosening level. The results of this study were as follows. (1) Percentage of initial loosening value to tightening-torque was increased in order of 0.7 mm external hex, 1.0 mm external hex, internal hex and internal taper and all values between each groups showed statistical significance (p<0.05). (2) Percentage of experimental value to initial loosening value was increased in order of internal hex, 0.7 mm external hex, 1.0 mm external hex and internal taper. Value of internal taper showed significant difference with that of 0.7 mm external hex and internal hex (p<0.05). (3) Percentage of experimental value to tightening torque was increased in order of 0.7 mm external hex, 1.0 mm external hex, internal hex and internal taper. Values of all groups showed statistical significance (p<0.05) except between the groups of 1.0 mm external hex and internal hex. Based on those results, there was no significant difference of loosening-torque by repetitive loading except internal taper. It is supposed that implant system with high resistant capability against initial loosening could be recommended for clinical use. In addition, in case of single implant restoration, 1.0 mm external hex or internal hex could be recommended rather than 0.7 mm external hex, and the use of internal taper would be the most useful way to reduce screw loosening.

• Journal of environmental and Sanitary engineering
• /
• v.12 no.3
• /
• pp.73-79
• /
• 1997

This research was intended as an investigation of applying Reduced Pressure Evaporation as efficient treatment method for landfill leachate. According to the variance of time, temperature, pressure and pH in experiments, the properties of leachate treatment are follows. The removal efficiencies of COD, NH$_{3}$-N, TOC, Conductivity and SS on the basis of reaction time was 96.4%-97.5%, -1.4%-53.7%, 81.7%-89.0%, 92.0%-95.3% and 99.86%-99.97%, respectively. When the pH of Influent was 7.5, the pH of effluent was increased to 10-11 with time elapse. It is concluded that the orgin of pH increase may be ammonia. When the properties of concentrate were investigated at the concentration ratio 90%(V/V), concentration difficiency represented in the ratio of experimental value/calculated value had following orders ; COD>TOC>NH$_{3}$-N>Conductivity>SS. Concentrate had good precipitation because of additive thermal treatment in the process. When evaporation experiments with pH adjustment of 4.0, 6.0, 7.5, 9.0 and 10.0 were performed ; Acidic evaporation experiments(pH 4.0, 6.0) showed low removal efficiency(81.6, 87.6%) of COD and high removal efficiency (97.5%. 84.6%) of NH$_{3}$-N at initial evaporation. Basic evaporation(pH 9.0, 10.0) showed high removal efficiency (97.2%, 98.9%) of COD and very low removal efficiency (-7.4%, -27.2%) of NH$_{3}$-N at initial evaporation.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.3
• /
• pp.200-204
• /
• 2003

This study was conducted to develop a technology for raising seedlings hydroponically using the bed in which the seedlings grew in nutrient solution without soil. In order to establish the optimum EC value of nutrient solution, six initial EC values (1, 2, 3, 4, 5 dS/m and control) of Yoshida's hydroponic solution were examined. Seedling height and dry weight increased with increasing below EC up to 3.0 dS/m, but showed no significant increase at higher than EC 3.0 dS/m. Nutrient solution with initial EC of 3.0 dS/m was good to be dropped down nearly to 1 dS/m after 15-day seedling culture. But those with initial EC of 4.0 and 5.0 dS/m were judged not appropriate because of high EC value in waste nutrient solution. Utilization efficiency of minerals of nutrient solution and rice endosperm was higher on the whole at initial EC of 2.0-3.0 dS/m. Considering seedling growth and utilization efficiency of supplied nutrient solution, initial EC is judged to be suitable at 3.0 dS/m.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.37 no.6
• /
• pp.465-472
• /
• 2019

The SPR (Single Photo Resection) is widely used as a method of estimating the EOPs (Exterior Orientation parameters) at the time of taking a photograph, but it requires an initial value and has a disadvantage of being sensitive to the initial value. In this study, we introduce quaternion-based single photo resection and PnP (Perspective-n-Point) algorithm that do not require initial values and compare the results. Photos were taken using a general smartphone, and the ground control point acquisition was based on the hybrid MMS (Mobile Mapping System) point cloud data possessed by the researchers. As a result, when the collinear condition based SPR is true value, quaternion-based SPR has higher attitude angle estimation accuracy than PnP algorithm. In case of camera position estimation, both algorithms showed accuracy within 0.8m when compared with ground control points.

• Journal of Environmental Science International
• /
• v.7 no.5
• /
• pp.707-716
• /
• 1998

The chemical characteristics of precipitation was investigated in Pusan area. Samples were collected from January to November in 1996 at 4 sites, and analyzed pH, major soluble ionic components(C $l^{[-10]}$ , N $O_3$$^{[-10]}$ , S $O_4$$^{2-}$, N $a^{+}$, $K^{+}$, N $H_4$$^{+}$, $Mg^{2+}$, $Ca^{2+}$). The order of anion and cation concentrations for the initial precipitation were C $l^{[-10]}$ ＞ S $O_4$$^{2-}$ ＞ N $O_3$$^{[-10]}$ , and $Ca^{2+}$ ＞ N $a^{+}$ ＞ N $H_4$$^{+}$ ＞ $Mg^{2+}$ ＞ $K^{+}$, respectively. At coastal sites(P1 and P2) C $l^{[-10]}$ and N $a^{+}$ of maritime sources (seasalt) were high, but at inland sites(P3 and P4) nss-C $a^{2+}$ and nss-S $O_4$$^{2-}$ were high. Calcium ion for the initial precipitation showed high value of enrichement factor(EF) relative to seawater composition. The contribution of seasalt to the composition of precipitation was higher at bite P1 (53.5%) than those of the other sites. Throughout the year the concentrations of major ions for the initial precipitation were low in the heavy rain season. The mean pH for the initial precipitation was 5.4 and showed the negative relationship with the precipitaion amount. The S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ do not play an important role in rain acidification due to the high(97%) neutralizing effect of amonia and calcium species.and calcium species.

• Journal of the Korean Society of Safety
• /
• v.15 no.2
• /
• pp.92-96
• /
• 2000

In this experiment, we studied about concentration characteristics of $NO_x$ and generation of ozone in the reactor of corona discharge type by using mixed gas of $NO/N_2$ and $N_2/O_2$. In the case of the initial NO concentration increased, decrease rate of NO concentration was weakened and discharge input power of minimum NO concentration became high. When NO concentration was high, NO decomposition limit was appeared. And NO reduction rate was decreased, when initial NO concentration and discharge input power increased. When discharge input power was 5W, we could know the most proper energy value for treatment of NO. When the concentration of initial NO increased, generation of ozone decreased and in the case of same concentration of NO, according to discharge input power increase, generation of ozone increased.

• Microbiology and Biotechnology Letters
• /
• v.25 no.5
• /
• pp.501-505
• /
• 1997

The effects of some nutrients and culture conditions on the growth and the production of fumonisin B$_{1}$, (FB$_{1}$) from Fusarium moniliforme NRRL 13569 were investigated in liquid culture. Xylose and soytone yielded the highest mycelial growth as the C- and N-source, respectively. The highest level of FB$_{1}$, was obtained when yeast extract was used as the N-source but no FB$_{1}$, from NaNO$_{3}$. While Fe$^{+++}$ showed inhibition effect on FB$_{1}$, production, Zn$^{++}$ enhanced the FB$_{1}$, production as well as the mycelial growth. FB$_{1}$, was maximally produced when the initial pH value and the specific surface area of the medium was adjusted to 5 and 1.4 cm$^{2}$/ml, respectively. FB$_{1}$ formation reached the maximum value (210, 000 ng/ml) in 30 days and then decreased in Czapek medium substitued with 1% xylose and 0.3% yeast extract, and supplemented with 0.2% NH$_{4}$H$_{2}$PO$_{4}$ where the initial pH value and the specific surface area of the medium are optimally controlled.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.8
• /
• pp.26-34
• /
• 1997

To develop ultrathin gate oxide for ULSI MOSFETs, for the first time, we fabricated MOS capacitors with 65.angs. thick initial oxide grown by high pressure oxidation (HIPOX) at 700.deg. C in 5 atmosphere $O_{2}$ ambient and then followed by rapid thermal nitridation (RTN) in N$_{2}$O ambient. The dielectric breakdown fields of the initial HIPOX oxide are 13.0 MV/cm and 13.8MV/cm for negative and positive gate bias, respectively and are dependent on nitridation temeprature and time.The lifetimes of the HIPOX oxides extractd by TDDB method are 1.1*10$^{8}$ sec and 3.4 * 10$^{9}$ sec for negative and positive stress current, respectively. The lifetime of the HIPOX oxide dfor negative stress current increases with nitridation time in N$_{2}$O ambient at 1100.deg.C, reaching maximum value stress curretn increases with nitridation time in N$_{2}$O ambient at 1100.deg. C reacing maximum value of 1.2*10$^{9}$ sec for 30 sec of nitridation time, and then subsequently decreases at the longer nitridation time. The lifetimes of the nitrided-HIPOX oxides are longer than 10 years when nitridations are carried out longer than about 50 sec and 12 sec at 1000.deg. C, and 1100.deg. C, respectively.

• Journal of KIISE
• /
• v.43 no.7
• /
• pp.812-819
• /
• 2016

This paper introduces and analyzes the theoretical basis and method of the conventional initial-value assignment problem and feasibility of image segmentation. The paper presents topological evidence and a method of appropriate initial-value assignment based on topology theory. Subsequently, the paper shows minimum conditions for feasibility of image segmentation based on separation axiom theory of topology and a validation method of effectiveness for image modeling. As a summary, this paper shows image segmentation with its mathematical validity based on topological analysis rather than statistical analysis. Finally, the paper applies the theory and methods to conventional Gaussian random field model and examines effectiveness of GRF modeling.

• Journal of Biosystems Engineering
• /
• v.17 no.3
• /
• pp.237-246
• /
• 1992

This study was conducted to investigate experimentally the effect of track tension on the tractive performance of rice combine. The experiment was carried out at the two in-door soil bins with soil types of loam and sandy loam. The initial track tension was varied by three different values of 0.71, 1.75 and 3.84kN at three different forward velocity settings of 0.17, 0.32 and 0.45m/s, respectively. The data acquisition system was designed and used for the measurement of pull, driving axle torque and its velocity under the test conditions to calculate the tractive efficiency. Results of the study were summarized as follows : 1) The effect of the initial track tension on the tractive efficiency was found being significantly dependent on soil types but not on forward velocities. Therefore, the benifit of adjusting the initial track tension may be obtained when the types of soils on which combines operate are changed. 2) In loam, tractive efficiency decreased with increase in track tension. However, it increased in sandy loam until it reached to a peak value and then decreased with increase in track tension. 3) The maximum tractive efficiency of the tested combine was obtained with an initial track tension of about 1.75kN on sandy loam, and below that on loam at about 5% slippage without being noticeably influenced by the forward velocity.