• Restorative Dentistry and Endodontics
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• 제24권3호
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• pp.465-472
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• 1999

The aim of this study was to determine the shear bond properties of four dentin bonding systems to internal cervical dentin, and to investigate the effect of the pretreatment for removing smear layer and position of dentin on shear bond strength of dentin bonding agents. The materials tested in this study were consisted of four commercially available dentin bonding systems[Allbond 2(AB), Clearfil Linerbond 2(CL), Optibond FL(OP), Scotchbond Multi-purpose(SB)], a restorative light-cured composite resin[Z100]J and a chelating agent[RC-prep(RC)]. Fifty-six freshly extracted human molars were used in this study. Dentin specimens were prepared by first cutting the root of the tooth 1mm below the cementoenamel junction with a diamond bur in a high speed handpiece under air-water coolant, and then removing occlusal part at pulp horn level by means of a second parallel section, The root canal areas were exposed by means of cutting the dent in specimens perpendicular to the root axis. Dentin specimens were randomly assigned to two groups(pretreated group, not-pretreated group) based on the pretreatment method of dentin surface. In pretreated group, RC was applied to dentin surface for 1minute and then rinsed with NaOCl. In not-pretreated group, dentin surface was rinsed with saline Each groups were subdevided into four groups according to dentin bonding systems. Four dentin bonding systems and a restorative resin were applied according to the directions of manufacturer. The dentin-resin specimens were embedded in a cold cure acrylic resin, and were cut with a low speed diamond saw to the dimension of $1{\times}1mm$. The cut specimens were divided into three groups according to the position of internal cervical dentin. The shear bond properties of dentin-resin specimens were measured with Universal testing machine (Zwick, 020, Germany) with the cross head speed of 0.5mm/min. From this experiment. the following results were obtained : 1. In case of shear bond strength, there was no significant difference among dentin bonding systems in not-pretreated groups, whereas in pretreated groups, the shear bond strengths of AB and of SB were statistically significantly higher than those of CL and of OP. 2. The shear bond strengths of AB and of SB in pretreated groups were significantly higher than those in not-pretreated groups. 3. The shear bond strengths of radicular layer of OP were higher than those of occlusal layer of OP in not-pretreated groups, and of AB in pretreated groups. The shear bond strengths of radicular layer of AB and of CL in not-pretreated groups were higher than those in pretreated group.

• 한국재료학회지
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• 제8권2호
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• pp.135-140
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• 1998

본 연구에서는 회전 원판 장치에 고분자-계면활성제의 혼합체를 첨가제로 사용하여 난류 유동장에서의 마찰저항 감소효과에 대해서 조사 연구하였다. 세가지의 분자량이 다른 PAA를 마찰저항 감소효과에 영향을 줄 수 있는 여러 인자들에 대헤서 살펴 보았다. 특히 이 연구에서는 이온성 고분자와 계면활성제의복합체가 마찰저항 감소현상에 어떠한 영향을 미치는 지에 대해서 연구하였다. 계면활성제와 고분자첨가제 사이의 형태학적 차이점에 특별한 관심을 가지고 실험을 하였으며 이온성 고분자의 pH에 대한 영향에 대해서도 조사하였다. 고분자와 계면활성제간의 복합체는 거대한 전해질과 같은 거동을 보이며 계면활성제가 고분자의 형태를 변화시켜 고분자의 크기를 확대시킨다. 따라서 이러한 복합체는 단일 고분자계와 비교해서 수력학적부피, 관성반경, 점도등의 값이 크게 나타나며 이렇게 팽창된 고분자는 난류 유동장에서의 마찰저항 감소효율을 증가시킨다.

• Restorative Dentistry and Endodontics
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• 제28권2호
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• pp.134-145
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• 2003

Mechanical properties and microleakage of two composites [conventional hybrid type DenFil (VERICOM Co., Anyang, Korea) / micro matrix hybrid type Esthet X (Dentsply Caulk, Milford, DE, U.S.A.)] were evaluated to assess whether variable light intensity curing is better than conventional curing technique. Curing was done for 40 seconds in two ways of 2 step soft-start technique and 5 step ramping technique. Three kinds of light intensities of 50, 100, $200{\;}mW/\textrm{cm}^2$ were initially used for 10, 20, 30 seconds each and the maximum intensity of $600 {\;}mW/\textrm{cm}^2$ was used for the rest of curing time in a soft-start curing tech nique. In a ramping technique, curing was done with the same initial intensities and the light intensity was increased 5 times with the same rate to the maximum intensity of $600{\;}mW/\textrm{cm}^2$. After determining conditions that showed no different mechanical properties with conventional technique, Esthet X composite was filled in a class V cavity, which dimension was $4{\times}3{\times}1.5{\;}mm$ and cured under those conditions. Microleakage was evaluated in two ways of dye penetration and maximum gap estimation through SEM observation. ANOVA and Spearman's rho test were used to confirm any statistical significance among groups. The results were as follows : 1 Several curing conditions of variable light intensities resulted in the similar mechanical properties with a conventional continuous curing technique, except conditions that start curing with an initial light intensity of $50{\;}mW/\textrm{cm}^2$. 2. Conventional and ramping techniques were better than soft-start technique in mechanical properties of microhardness and compressive strength. 3. Soft-start group that started curing with an initial light intensity of $100{\;}mW/\textrm{cm}^2$ for 10 seconds showed the least dye penetration. Soft-start group that started curing with an initial light intensity of $200{\;}mW/\textrm{cm}^2$ for 10 seconds showed the smallest marginal gap, if there was no difference among groups. 4. Soft-start technique resulted in better dye-proof margin than conventional technique(p=0.014) and ramping technique(p = 0.002). 5. There was a very low relationship(p=0.157) between the methods of dye penetration and marginal gap determination through SEM evaluation. From the results of this study, it was revealed that ramping technique would be better than conventional technique in mechanical properties, however, soft-start technique might be better than conventional one in microleakage. It was concluded that much endeavor should be made to find out the curing conditions, which have advantages of both aspects or to solve these kinds of problems through a novel idea of polymerization.

• 한국식품영양과학회지
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• 제6권1호
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• pp.1-8
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• 1977

The sample persimmons were obtained from the of Yung-am Kun, Korea on October 24, and November 9, 1973. These persimmons were kept at room temperature overnight, then packed and stored on the following day at $0^{\circ}C$ and $85{\sim}100%$ humidity. Seven experimental items were studied : 1. control, 2. packing with excelsior in wooden boxes, 3. packing with rice hull in wooden boxes, 4. packing in bags of 0.03 mm polyethylene membrane, 5. packing in bags of 0.06 mm polyethylene membrane, 6. packing in bags of 0.08 mm polyethylene membrane, 7. packing in sealed desiccators. The dimension of polyethylene bags were $14{\times}28cm$ and three persimmons were packing in each bag. The results are as follows: 1. The persimmons both in polyethylene bags and in desiccators lost only 1 % or less of weight, while in control (1) packing with excelsior (2) or with rice hull (3) the loss was 6-7 % in weight after $2{\sim}3$ months. The persimmons became visibly shriveled and spongy-like in it's texture when it lost 5 % of weight. 2. Carbon dioxide content within the polyethylene bags and desiccators rapidly increased during the early storage period, and reached 5 % (in 0.03 mm polyethylene bags) to 50 % or more (in desiccator) after 1 month. In the polyethylene bags of 0.08 mm and desiccator, the carbon dioxide accumulated to a dangerous level and the persimmon showed physiological damage in a longer storage period. 3. The advance of after-ripening and deterioration of persimmon sealed in the polyethylene bags was slower than that in open bags when moved out to room temperature from the chilling and the polyethylene bags of 0.06 mm retarded the after-ripening most effectively. 4. On the basis of these results, a temperature of $0^{\circ}C$, relative humidity of almost $85{\sim}100%$ and combinations of 5 % oxygen and $5{\sim}8%$ carbon dioxide seem to be the optimum condition for the storage of persimmon (Teabong-Si). The most successful method of storing was to pack them in polyethylene bags of 0.06 mm and then to store them at $0^{\circ}C$.

• 한국산림과학회지
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• 제78권3호
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• pp.323-330
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• 1989

한국산(韓國産) 소나무천연림(天然林)의 효과적인 현존량(現存量) 추정식(推定式)을 파악하기 위하여 4개(個) 지역형별(地域型別) 전형적인 수형을 가지는 임분(林分)을 대상으로 임분별(林分別) 10주(株)씩 총 40주(株)의 표본목(標本木)을 선정(選定) 벌목(伐木)하여 임분별(林分別), 부위별(部位別) 현존량(現存量) 추정식(推定式)을 3개(個) 상대성장식(相對成長式)(logWt=A+BlogD, logWt=A+B $1ogD^2H$, logWt=A+BlogD+ClogH)에 의하여 유도한 결과 전반적으로 logWt=A+BlogD-ClogH 식의 적합도(適合度)가 높았다. 그러나 고사지(故死枝)와 모구(毬果)의 경우 흉고직경(胸高直徑)과 수고(樹高) 즉, 개체목(個體木)의 크기 인자와의 관계(關係)가 적은 것으로 나타났다. 실용성(實用性)을 고려하여 4개(個) 임분(林分) 전체의 표본목(標本木) 40주(株)에 대한 일괄상대성장식(一括相對成長式)을 유도하고 임분별(林分別) 회귀식간(回歸式間)의 분산(分散), 기울기, 절편(截片)의 차이 유무를 검정한 결과 흉고직경(胸高直徑)만을 독립변수(獨立變數)로 하는 경우 보다 흉고직경(胸高直徑)과 수고(樹高)를 독립변수(獨立變數)로 할 경우 지성형간(地城型間)의 차이를 어느정도 배제할 수 있었으나, 임분별(林分別) 회귀식간(回歸式間)의 분산(分散) 절편(截片)에서 유기적(有機的)인 차이를 보임으로써 4개(個) 임분(林分)에 대한 일괄상대성장식(一括相對成長式)의 작용은 적합하지 않은 것으로 나타났다.

• 대한간호학회지
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• 제17권3호
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• pp.184-194
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• 1987

The purposes of this study were; 1) to gather data relevant to demographic features. major main management practices, and the level of impairment of the activities of daily living (ADL) of patients with back pain, 2) to test the sensitivity of the Korean Pain Rating Scale and the Graphic Rating Scales, and 3) to identify indirect indicators of back pain by analysing pain related-behaviors. The level of pain was measured by Korean Pain Rating Scale(KPRS) and Graphic Rating Scales(GRS) developed by the reserchers. The GRS consists of two dimensions; the pain intensity (sensory) and unpleasantness (affective) measures. Of the 1,650 diagnosed back pain patients, from January 4 through June 30, 1987 by visiting outpatients' clinics of orthopedic and neurosurgical departments at 11 university hospitals in different districts of Korea, 330 men and women patients were self-selected by responding to the mailed questionnaires. The results were summarised as follows: Male exceeded female patients in number and onset of back pain were more prevalent in the age groups of 20s and the 30s. The average duration of suffering from the pain were 11 months, sixty three (19.1%) of the subjects retired from their jobs, one third(36.7%) have teen hospitalized for the treatment of back pain. In two thirds(64.8%) of the cases pain was characterized as lower back pain. The average sleep hour was 6.8 hours per 24 hours and the average rest hour during the day was 3.3 hours. The mean percentage of pain measured by GRS was higher than that of KPRS. The level of sensory intensity as well as the affective level of pain measured by KPRS and GRS were not highly correlated (sensory intensity r=0.4986, affective r=0.5029) which indicated low discriminative power. On the other hand, intercorrelation between sensory and affective dimension measured by KPRS and GRS showed moderate interrelation(r=0.7247; r=0.7899). One-third(32.5%) of the subjects complied with the hospital prescribed treatment while the other one-third(31.5%) depended on self-remedy and traditional practices, and the last one-third did not imply any pain management practices. The following 6 pain-related behaviors such as length of hospitalization, rest hour during day hours, varieties of pain management practice implied, number of pain sites, need for ADL and discomfort accompanied by ADL revealed to be important indicators of back pain. An investigation of sociodemographic features of patients with back pain in a larger context, i.e. with bigger number of respondents is recommended. Tests for construct validity of KPRS, i.e. factor analysis is further recommended.

• 대한소아치과학회지
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• 제33권2호
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• pp.323-328
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• 2006

상아질 형성부전증은 상아질 형성 이상이 초래되는 유전성 질환으로, 주로 상염색체 우성으로 유전된다. 8000명당 1명꼴로 발생하며 남녀 성별의 차이가 없고 유치열과 영구치열 모두에서 나타난다고 알려져 있으며, Shield등은 세 가지 유형으로 분류하였다. 이환 받은 치 아는 다양한 치아 변색, 법랑질의 박리, 급속도의 상아질의 파괴, 심한 마모현상 등의 임상소견을 보인다. 따라서 치간이개, 고경감소, 저작능력의 저하, 치태와 치석의 침착 등이 나타날 수 있다. 방사선학적 소견으로 치경부 수축 구근 상치관, 짧고 가는 치근, 치수강과 근관의 폐색, 건전치 에서 치근부 병변 등이 보인다. 상아질 형성부전증에 대한 치료 목표는 심미성 회복, 저작능력회복, 교합고경의 회복을 들 수 있다. 본 증례들은 치아의 마모와 변색을 주소로 경북대학병원 소아치과에 내원한 두 명의 환아들에서 임상 및 방사선학적 검사 소견상 상아질 형성 부전증으로 판단되어 환아의 손상된 치아에 대해 치료를 시행하여 기능적 심미적으로 만족할 만한 결과를 얻어 이를 보고하는 바이다.

• 한국조사연구학회지:조사연구
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• 제12권2호
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• pp.113-144
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• 2011

본 연구의 목적은 청년 취업자의 직무만족도와 이직의사의 다양한 변화형태를 추정하여 잠재계층을 분류하고, 두 변수에 영향을 미치는 직무적합도(전공적합도, 교육수준적합도, 기술수준적합도)와의 효과를 밝히는 것이다. 이를 위하여 청년패널 2001의 만 15∼29세 청년 취업자를 대상으로 한 2001년부터 2006년까지의 종단자료를 이용하였다. 직무만족도와 이직의사의 잠재계층을 동시에 도출하기 위해 준모수적 집단중심 접근 방법의 확장모형인 이중 변화형태 모형(dual trajectory model)을 적용하였다. 분석 결과, 직무만족도 변화에 따른 잠재계층은 4개로 분류되었고, 변화형태에 따라 증가집단, 감소집단, 중간수준집단, 고수준집단으로 명명하였다. 이직의사 변화에 따른 잠재 계층은 3개로 분류되었고, 변화형태에 따라 저수준집단, 유지집단, 급감소집단으로 명명하였다. 직무만족도와 이직의사에 시간의존적 변수인 전공적합도, 교육수준적합도, 기술수준 적합도의 영향력을 검증한 결과, 직무만족도가 낮거나 이직의사가 높은 집단에는 교육수준 적합도 또는 기술수준적합도의 영향력이 유의하게 나타났다. 본 연구는 오랜 기간 직무만족도가 낮거나 이직의사를 지속적으로 가지고 있는 청년 취업자들을 위한 대책을 마련하는데 도움을 줄 것이다. 또한 잠재계층 모형을 확장시켜 두 가지 변수의 잠재계층을 동시에 도출하고, 그 잠재계층을 결정짓는 데 미치는 시간의존적 독립변수의 효과를 검증하는 종단연구 방법을 적용했다는 점에서 연구방법론적 측면에서 의의가 있다.

• 여성건강간호학회지
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• 제7권3호
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• pp.241-255
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• 2001

This is a cross-sectional descriptive study which compares the level of postpartum women's physical, phychological, neurosensory fatigue between rooming-in and non rooming-in groups. The data were collected by using self-report questionnaire from April 1 to May 31, 2001. Subjects were 68 mothers who opted the rooming-in choice and 98 mothers who did not choose the rooming-in at one hospital in Seoul, Korea. They all had NSVD. The research questionnaire consisted of 36 items on general chracteristics and 30 items on postpartum fatigue developed by Pugh (1993). The data were analyzed by using the SPSS 10.0 window program. The results of this study were as follow: 1. There was significant statistical difference in general characteristics between rooming-in and non rooming-in groups in prenatal class attendance ($x^2$=3.935, p=0.047), maternal fetal attachment score (t=2.130, p=0.035), husband attendance during the labor and delivery ($x^2$=9.147, p=0.002), breast feeding ($x^2$=12.503, p=0.000), and self feeding time including bottle feeding (t=4.588, p=0.000). 2. There was no significant statistical difference in the level of total fatigue score between two groups (t=0.282, p=0.780). 3. The physical and neurosensory fatigue scores were slightly higher in rooming-in group ($21.63{\pm}4.92$, $18.53{\pm}4.60$) than those ($20.71{\pm}5.78$, $18.23{\pm}5.39$) of non rooming-in group. And the phychological fatigue score was slightly higher in non rooming-in group ($17.67{\pm}4.95$) than that ($17.04{\pm}4.63$) of rooming-in group. However, there was no significant statistical difference in the level of three sub-dimension fatigue between two groups (t=1.068, p=0.287; t=-0.827, p=0.410; t=0.368, p=0.714). 4. Even after controlling characteristics showed significant differences between two groups, there was no significant statistical difference in the level of fatigue between two groups (F=0.135, p=0.714). According to this study, there was no significant statistical difference in the level of postpartum fatigue whether they were rooming-in or not. Based on this result, the common notion of rooming-in mothers will be more fatigue than non rooming-in mothers is proved to be false. However, it is necessary to develop appropriate nursing interventions to meet the need of mothers who decide to rooming-in.

• 치과방사선
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• 제28권1호
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• pp.27-36
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• 1998

The purpose of this study was to obtain information on the clinical and radiographic features of the fibro-osseous lesions in the jaws. For this study, the author examined and analysed the clinical records and radiographs of 71 cases of 68 patients in fibrous dysplasia, 35 cases of ossifying fibroma and 30 cases of 16 patients of periapical cemental dysplasia diagnosed by clinical and radiographic or histopathological examinations. The obtained results were as followings: L Fibrous dysplasia occurred most frequently in the 2nd decade (30.0％), ossifying fibroma in the 3rd-4th decades, periapical cemental dysplasia in the 4th decade, and all of three lesions showed slight predilection in females. In most cases, chief complaints were painless facial swelling in fibrous dysplasia and ossifying fibroma, and periapical cemental dysplasia was found accidentally in radiographs. 2. Fibrous dysplasia was occurred more frequently in maxilla, ossifying fibroma in mandible and both lesions in premolar-molar area. Periapical cemental dysplasia was occurred most frequently in the mandibular anterior area. The size of fibrous dysplasia was larger than that of ossifying fibroma, and the shape of ossifying fibroma was more round and elliptical than fibrous dysplasia whose was fusiform. 3. Fibrous dysplasia was shown homogeneous radiopaque shadow of 57.6％ and ossifying fibroma & periapical cemental dysplasia were shown mixed appearance of radiolucency and radiopacity shadows at 74.2％, 60.0％, respectively. 4. Fibrous dysplasia was entirely shown poorly defined at 87.7％, but ossifying fibroma & periapical cemental dysplasia were shown well outlined at 60.0％, 70.0％, respectively. 5. Cortical thinning and expansion were observed in fibrous dysplasia and ossifying fibroma, and severe in ossifying fibroma than fibrous dysplasia, and those signs were not seen in periapical cemental dysplasia. Loss of lamina dura was dominant in fibrous dysplasia and root resorption was dominant in ossifying fibroma. Displacement of mandibular canal and the degree of the increase of vertical dimension were alike in both lesions. Displacement of maxillary sinus or nasal cavity, thinning & expansion of the maxillary sinus were dominant in fibrous dysplasia. 6. Polyostotic fibrous dysplasia was occurred at 5.9％, Multiple periapical cemental dysplasia at 43.7％. Occurrence rate in the edentulous area of fibrous dysplasia and ossifying fibroma were 7.0％, 8.6％, respectively.