• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.226-232
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• 2010

Incidence of tooth impaction varies from 5.6 to 18.8% of the population. Failure of eruption of the first and second permanent molars is rare; the prevalence in the normal population is 0.01% in case of the first permanent molar, and 0.06% in case of the second permanent molar. Permanent molars are particularly important for providing sufficient occlusal support and co-ordinating facial growth. Failure of eruption of permanent molars may result in various complications such as decrease in vertical dimension, posterior open bite, extrusion of antagonistic teeth, resorption and inclination of adjacent teeth, formation of cyst and so on. Treatment options of impacted teeth are periodic observation, surgical exposure, surgical exposure with subluxation, orthodontic relocation, and surgical extraction before prosthetic treatment. Early diagnosis and treatment are important, because delayed treatment induces various problems such as decreased spontaneous eruptive force, decreased successful percentage, increased treatment period, increased various complications. Prevalence of the failure of mandibular first molars is rare but eruptive guidance before extraction of impacted teeth is necessary due to importance of permanent molars. We reported two cases of surgical exposure of impacted mandibular first molar. In these cases, we could observe different result of the impacted mandibular first molar after surgical exposure.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.11
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• pp.1537-1544
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• 2015

Meat and carcass quality attributes are of crucial importance influencing consumer preference and profitability in the pork industry. A set of 400 Berkshire pigs were collected from Dasan breeding farm, Namwon, Chonbuk province, Korea that were born between 2012 and 2013. To perform genome wide association studies (GWAS), eleven meat and carcass quality traits were considered, including carcass weight, backfat thickness, pH value after 24 hours (pH24), Commission Internationale de l'Eclairage lightness in meat color (CIE L), redness in meat color (CIE a), yellowness in meat color (CIE b), filtering, drip loss, heat loss, shear force and marbling score. All of the 400 animals were genotyped with the Porcine 62K SNP BeadChips (Illumina Inc., USA). A SAS general linear model procedure (SAS version 9.2) was used to pre-adjust the animal phenotypes before GWAS with sire and sex effects as fixed effects and slaughter age as a covariate. After fitting the fixed and covariate factors in the model, the residuals of the phenotype regressed on additive effects of each single nucleotide polymorphism (SNP) under a linear regression model (PLINK version 1.07). The significant SNPs after permutation testing at a chromosome-wise level were subjected to stepwise regression analysis to determine the best set of SNP markers. A total of 55 significant (p<0.05) SNPs or quantitative trait loci (QTL) were detected on various chromosomes. The QTLs explained from 5.06% to 8.28% of the total phenotypic variation of the traits. Some QTLs with pleiotropic effect were also identified. A pair of significant QTL for pH24 was also found to affect both CIE L and drip loss percentage. The significant QTL after characterization of the functional candidate genes on the QTL or around the QTL region may be effectively and efficiently used in marker assisted selection to achieve enhanced genetic improvement of the trait considered.

• Food Science of Animal Resources
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• v.25 no.3
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• pp.322-327
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• 2005

This study was intended to provide basic information which might be useful in increasing added values to the pork from Korean native black pigs (KNP), through comparative evaluation on carcass characteristics and meat qualities between KNP and four exotic breed groups including Duroc (DD), Landrace (LL), Yorkshire (YY), and LYD-cross (1/4LL 1/4YY, 1/2DD), and the results were summarized as follows. Live weight carcass weight, dressed meat weight, skin weight, fat weight and bone weight of KNP were significantly (p<0.05) lower than those of DD, LL, YY and LYD-cross. Carcass yield and dressed meat yield were also significantly (p<0.05) lower in KNP than other 4 groups, however, total fat, skin, bone, kidney and kidney fat in percentage were significantly (p<0.05) higher for KNP than others. Dressed meat yield was highest for YY, followed by LYD-cross and KNP. Weight of belly was 6.12, 9.43, and 9.52 kg for KNP, YY and LYD-cross, respectively. Percent belly of KNP was $11.11\%$ while other groups ranged from 11.5 to $12.2\%$ Shear force value was not different among the treatments. KNP had significantly (p<0.05) lower water holding capacity (WHC), and cooking loss, but significantly (p<0.05) higher in juiciness comparatively. KNP had significantly (p<0.05) higher $a^{*}$ value while DD had significantly (p<0.05) lower than other breeds.

• Progress in Medical Physics
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• v.13 no.4
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• pp.195-201
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• 2002

Several investigators have presented the effects of external magnetic fields on the dose distributions for clinical electron and photon beams. We focus the low energy electron beam with more lateral scatter In this study we calculated the beam profiles for an clinical electron beam of 6 MeV with longitudinal magnetic fields of 0.5 T-3.0 T using a Monte Carlo code. The principle of dose enhancements in the penumbra region is to deflect the laterally scattered electrons from its initial direction by the skewness of the laterally scattered electrons along the direction of magnetic field lines due to Lorentz force under longitudinal magnetic field. To discuss the dose enhancement effect on the penumbra area from the calculated results, we introduced the simple term of penumbra reduction ratio (PRR), which is defined as the percentage difference between the penumbra with and without magnetic field at the same depth. We found that the average PRR are 33%, and 49% over the depths of 1.5 cm, 2.0 cm, and 2.4 cm for the magnetic fields of 2.0 T and 3.0 T respectively. For the case of 0.5 T and 1.0 T the effects of magnetic filed were not observed significantly. In order to obtain the dose enhancement effects by the external magnetic field, we think that its strength should be more than 2 T approximately. We expect that the PRR would be saturated to 50-60% with magnetic fields of 3 T-5 T As a result of these calculations we found that the penumbra widths can be reduced with increased magnetic fields. This Penumbra reduction is explained as a result of electron lateral spread outside the geometrical edges of the beam in a longitudinal magnetic field. This means that the electron therapy benefits from the external magnetic fields.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.38-43
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• 2005

Effects of fermented food waste feeds on meat quality and physico-chemical characteristics of fully grown pigs were investigated. Two treatments were tried in this study; commercial feed (control) and fermented food waste feed(FFWF). Except for much thicker backfat of control, carcass traits, carcass weight, dressing percentage, carcass grade, cooking loss, shear force, water-holding capacity, drip loss, NPPC meat color, and marbling score of commercial feed(control)- and fermented food waste feed (FFWF)-fed pigs were not significantly different. Primal cut weights and meat percentages were significantly different (p<0.05) between control and FFWF. pH of FFWF loin was significantly lower (p<0.05) than that of control. FFWF loin showed higher L*-value and lower a*-value compared to control.

• The korean journal of orthodontics
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• v.32 no.1 s.90
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• pp.51-57
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• 2002

The purpose of this study was to compare in vitro shear bonding strength with three different enamel surface preparations (1) 30% sulfated polyacrylic acid with 0.3M lithium sulfate (2) 40% sulfated polyacrylic acid with 0.3M lithium sulfate (3) 37% phosphoric acid. 105 extracted human premolar teeth were divided into each three groups of 35. Metal brackets were bonded to teeth in the three groups. The same self curing resin was used for all groups. A shearing force was applied to the teeth. After debonding, bases of bracket and enamel surfaces were examined under steroscopic microscope to determine the failure modes. Statistical analysis of the data was carried out with one way ANOVA and Student t- test. The results were as follows. 1. Shear bond strength values for the 30% polyacrylic acid and 40% polyacrylic acid group were approximately two thirds of the phosphoric acid group. It maintains clinically acceptable but not enough bond strength. 2. There was no statistically significant difference in shear bond strengths between 30% and 40% polyacrylic acid group. 3. The failure modes of brackets had some differences. In polyacrylic acid groups, the percentage of adhesive/enamel failure was higher than that of adhesive/ bracket interface failure. On the contrary in phosphoric acid groups, the results were reversed. Further study of bond strength could be required. If polyacrylic acid enamel conditioning is used clinically.

• Korean Journal of Remote Sensing
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• v.21 no.6
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• pp.457-468
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• 2005

Increasing of impervious surface resulting from urban development has negative impacts on urban environment. Therefore, it is absolutely necessary to estimate and quantify the temporal and spatial aspects of impervious area for study of urban environment. In many cases, conventional image classification methods have been used for analysis of impervious surface fraction. However, the conventional classification methods have shortcoming in estimating impervious surface. The DN value of the each pixel in imagery is mixed result of spectral character of various objects which exist in surface. But conventional image classification methods force each pixel to be allocated only one class. And also after land cover classification, it is requisite to additional work of calculating impervious percentage value in each class item. This study used the spectral mixture analysis to overcome this weakness of the conventional classification methods. Four endmembers, vegetation, soil, low albedo and high albedo were selected to compose pure land cover objects. Impervious surface fraction was estimated by adding low albedo and high albedo. The study area is the Tanchon watershed which has been rapidly changed by the intensive development of housing. Landsat imagery from 1988, 1994 to 2001 was used to estimate impervious surface fraction. The results of this study show that impervious surface fraction increased from $15.6\%$ in 1988, $20.1\%$ in 1994 to $24\%$ in 2001. Results indicate that impervious surface fraction can be estimated by spectral mixture analysis with promising accuracy.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.12
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• pp.1923-1932
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• 2019

Objective: We investigated visual marbling level (VML) influence on pork loin physicochemical traits, consumer palatability responses, VML liking, purchase intent, and their relationships. Methods: For each of five slaughtering dates, at 24-h postmortem, nine paired Duroc castrated male boneless Longissimus dorsi (LD) muscles were categorized into low (LM, score 1 to 2, n = 3), medium (MM, score 3 to 4, n = 3), and high (HM, score 5 to 6, n = 3) VML. Meat physicochemical quality traits and consumer responses (n = 389) on palatability and VML liking, and purchase intent were evaluated. The experiment was in randomized complete block design. Analysis of variance, Duncan's multiple mean comparisons, and correlation coefficients were determined. Results: VML correspond to crude fat (r = 0.91, p<0.01), but both were reversely related to moisture content (r = -0.75 and -0.91, p<0.01, respectively). As VML increased, ash (p<0.05) and protein (p = 0.072) decreased, pH and $b^{\star}$ increased (p<0.05), but drip, cooking (p<0.05) and thawing (p = 0.088) losses decreased. Among treatments, muscle fiber diameter, sarcomere length, total and insoluble collagen contents, $L^{\star}$, and $a^{\star}$ did not differ (p>0.05). Compared to the others, HM had lower collagen solubility percentage (p<0.05), but similar (p>0.05) Warner-Bratzler shear force (WBSF). No differences (p>0.05) were found in juiciness, overall flavor, oiliness, and overall acceptability, but HM was more tender (p<0.05) than the others. Based on VML, consumers preferred MM to HM (p<0.05), while LM was similar to MM and HM (p>0.05). Corresponding to VML preference (r = 0.45, p<0.01), consumers (83%) would (p<0.01) definitely and probably buy MM, over LM (74%), and HM (68%), respectively. Conclusion: Increasing VML in pork LD altered its chemical composition, slightly increased pH, and improved water holding capacity, thereby improving its tenderness acceptability. Marbling might reduce chewing resistance, as lower collagen solubility in HM did not impact tenderness acceptability and WBSF. While HM was rated as most tender, consumers visually preferred and would purchase MM.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.671-679
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• 2008

The effect of Pre-cooled Turbojet Engine installation and nozzle exhaust jet on Hypersonic Turbojet EXperimental aircraft(HYTEX aircraft) were investigated by three-dimensional numerical analyses to obtain aerodynamic characteristics of the aircraft during its in-flight condition. First, simulations of wind tunnel experiment using small scale model of the aircraft with and without the rectangular duct reproducing engine was performed at M=5.1 condition in order to validate the calculation code. Here, good agreements with experimental data were obtained regarding centerline wall pressures on the aircraft and aerodynamic coefficients of forces and moments acting on the aircraft. Next, full scale integrated analysis of the aircraft and the engine were conducted for flight Mach numbers of M=5.0, 4.0, 3.5, 3.0, and 2.0. Increasing the angle of attack $\alpha$ of the aircraft in M=5.0 flight increased the mass flow rate of the air captured at the intake due to pre-compression effect of the nose shockwave, also increasing the thrust obtained at the engine plug nozzle. Sufficient thrust for acceleration were obtained at $\alpha=3$ and 5 degrees. Increase of flight Mach number at $\alpha=0$ degrees resulted in decrease of mass flow rate captured at the engine intake, and thus decrease in thrust at the nozzle. The thrust was sufficient for acceleration at M=3.5 and lower cases. Lift force on the aircraft was increased by the integration of engine on the aircraft for all varying angles of attack or flight Mach numbers. However, the slope of lift increase when increasing flight Mach number showed decrease as flight Mach number reach to M=5.0, due to the separation shockwave at the upper surface of the aircraft. Pitch moment of the aircraft was not affected by the installation of the engines for all angles of attack at M=5.0 condition. In low Mach number cases at $\alpha=0$ degrees, installation of the engines increased the pitch moment compared to no engine configuration. Installation of the engines increased the frictional drag on the aircraft, and its percentage to the total drag ranged between 30-50% for varying angle of attack in M=5.0 flight.

• Animal Bioscience
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• v.35 no.7
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• pp.1069-1079
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• 2022

Objective: The objective of this study was to investigate the effect of 4-month intensive feeding on the meat quality, fatty acid profile, flavor, and growth performance of grazing Hulunbuir sheep (HBS). Methods: The HBS were selected 4-months after birth in a pasture rearing system as the experimental animals (n = 44, female, average body weight 23.8±2.2 kg) then divided equally into pasture-based grazing fattening (PAS) and concentrate-included intensive fattening (CON) groups for another 4-month finishing. When finished fattening, all animals were slaughtered to collect musculus longissimus dorsi subcutaneous adipose tissue and to investigate the influences on meat quality, fatty acid profile, flavor and growth performance. Results: The results showed lambs in CON group got significantly higher live weight, hot carcass weight, and dressing percentage. The CON group had significantly higher value of redness (a^*), lightness (L^*) and water holding capacity (p<0.05), significantly lower value of Warner-Bratzler shear force than the PAS group (p<0.05). The subcutaneous fat from CON group lambs demonstrated a significantly higher content of C18:1 and C18:2 (p<0.05), but lower C14:0 and C16:0, indicating an increased degree of unsaturated fatty acid. The content of 4-methyloctanoic acid, 4-ethyloctanoic acid and 4-methylnonanoic acid had increased 2 to 4 times, representing a more intense odor in the CON group. However, the values were still lower than most sheep breeds reported, indicating the indoor feeding system could not fundamentally deteriorate the excellent meat characteristic of HBS. Conclusion: It was evident that lambs in CON group exhibited a better meat production performance, improved in meat color, texture and healthier fatty acid profile through pasture-weaned concentrate included intensive fattening system, which offers a good alternative regimen for lamb finishing and has a wide prospection in the HBS meat industry.