• The korean journal of orthodontics
• /
• v.35 no.1 s.108
• /
• pp.82-89
• /
• 2005

Mandibular widening is one method of mandibular distraction osteogenesis, which has anatomic limitations such as curved surface, mandibular condyle and narrow arch. The purpose of this study was to understand the biomechanics of various mandibular widening procedures Experimental models consisted of 6 groups according to different osteotomy hues and distractor positions. The results of this study showed different expansion patterns. which meant the feed for proper approaches in mandibular widening.

• Journal of Radiation Protection and Research
• /
• v.29 no.1
• /
• pp.17-23
• /
• 2004

In order to save time and money needed in the purchase commonly used gamma-ray standard sources, a new radioactive standard source was manufactured by the neutron activation of some regent in the research reactor HANARO. The source was manufactured with an aqueous solution by mixing and dissolving the irradiated reagents. The manufactured source was compared with a commercial standard source. It was confirmed that it could be used as an efficiency calibration source. Also, in order to compare the variation of efficiency due to the volume difference for various containers used in radioactivity assay, the efficiency variation as a function of sample volume was investigated.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.91-91
• /
• 2015

반도체 공정의 발전에 의해 최근 생산되는 메모리 등은 십 수 나노미터까지 좁아진 선 폭을 갖게 되었다. 이러한 이유로, 기존에는 큰 문제를 발생시키지 않던 나노미터 영역의 입자들이 박막 증착 공정과 같은 반도체 제조공정 수율을 저감시키게 되었다. 따라서 오염입자의 유입을 막거나 제어하기 위해 transmission electron microscopy (TEM)나 scanning electron microscopy (SEM)과 같은 전자현미경을 활용한 비 실시간 입자 측정 방법 및 광원을 이용하는 in-situ particle monitor (ISPM) 및 전기적 이동도를 이용한 scanning mobility particle sizer (SMPS) 등 다양한 원리를 이용한 실시간 입자 측정방법이 현재 사용중에 있다. 이 중 진공 내 입자의 수농도를 측정하기 위해 개발된 particle beam mass spectrometer (PBMS) 기술은 박막 증착 공정 등 chemical vapor deposition (CVD) 방법을 이용하는 진공공정에서 활용 가능하여 개발이 진행되어 왔다. 본 연구에서는 PBMS의 한계점인 입자 밀도, 형상 등의 특성분석이 용이하도록 PBMS와 scanning electron microscopy (SEM), 그리고 energy dispersive spectroscopy (EDS) 기술을 결합하여 입자의 직경별 개수농도, 각 입자의 형상 및 성분을 함께 측정 가능하도록 하였다. 협소한 반도체 제조공정 내부 공간에 적용 가능하도록 기존 PBMS 대비 크기 또한 소형화 하였다. 각 구성요소인 공기역학 집속렌즈, electron gun, 편향판, 그리고 패러데이 컵의 설치 및 물리적인 교정을 진행한 후 입자발생장치를 통해 발생시킨 sodium chloride 입자를 상압 입자 측정 및 분류장치인 SMPS 장치를 이용하여 크기별로 분류시켜 압력차를 통해 PBMS로 유입시켜 측정을 진행하였다. 나노입자의 입경분포, 형상 및 성분을 측정결과를 토대로 장치의 측정정확도를 교정하였다. 교정된 장치를 이용하여 실제 박막 증착공정 챔버의 배기라인에서 발생하는 입자의 수농도, 형상 및 성분의 복합특성 측정이 가능하였으며, 최종적으로 실제 공정에 적용가능하도록 장치 교정을 완료하였다.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.34 no.4
• /
• pp.709-717
• /
• 2007

Impaction of maxillary incisor is rare than the third molar and canine, but its rate is higher than the other anterior teeth due to frequent mesiodens, trauma and variation of root formation (root dilaceration etc.). It is often observed in the dental age of about eight years and over. It will be occurred that the space loss, midline deviation and cyst formation due to the impaction of maxillary incisor. So it is important to evaluate the precise location of impacted tooth and to make appropriate treatment plan. Treatment would be surgical extraction or expectation for spontaneous eruption. If the impacted tooth has no pathologic change and development of the root is favorable, orthodontic traction is recommended for recovery of function and esthetics. In these cases, we performed orthodontic traction for the eruption of impacted maxillary incisors, and obtained satisfactory results.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.32 no.3
• /
• pp.437-443
• /
• 2005

Dilaceration is most common in maxillary central incisor. Impaction by dilacerated tooth cause orthodontic problem such as tilting of adjacent tooth, midline deviation. Dilaceration is caused by trauma, cyst, other origin and tooth shape, degree of root curvature, location in the alveolar bone, ability of spontaneous eruption should be considered whether treat or not. Labially and lingually dilacerated tooth is difficult to spontaneous eruption. Thus, Prosthetic treatment alternative with extraction, auto transplantation, orthodontic traction with surgical exposure is included within the treatment alternative. These cases are about impacted central incisor with dilacerated root. We use closed eruption technique and guide impacted tooth into normal position by orthodontic traction.

• The korean journal of orthodontics
• /
• v.1 no.1
• /
• pp.15-20
• /
• 1970

The author investigated on the responses of pulp and dentine following tooth movements. The material consisted of fifty-four intact teeth from twenty-seven adult white rats. The half of the teeth were employed as controls and the other half served as experimental group. These teeth were moved with forces ranging from 30 grams to 120 grams for from 3 to 7 days. All these were extracted immediately after the force was relieved. The main pulp changes in the experiment were vacuolization of the pulp tissue and circulatory disturbances. The magnitude of the force had an important role. In addition to these changes, the resorption in dentine and cementum was observed, which was related to the magnitude of the force and the duration of experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.9
• /
• pp.617-625
• /
• 2022

This study investigates the use of movable calibration target for gyroscopic and accelerometer bias compensation of inertial measurement units for firing lane alignment. Calibration source is detected with the help of vision sensor and its information in fused with other sensors on launcher for error correction. An algorithm is proposed and tested in simulation. It has been shown that it is possible to compensate sensor biases in firing launcher in few seconds by accurately estimating the location of calibration target in inertial frame of reference.

• The korean journal of orthodontics
• /
• v.37 no.2 s.121
• /
• pp.125-136
• /
• 2007

Objective: Soft tissue changes due to orthodontic treatment has large individual variation. Therefore continuous evaluation during treatment is required. Patients with fixed orthodontic appliances often wonder if their lip positions will change after the removal of brackets, but only a few studies exist on this topic. The objective of this study was to evaluate the changes of the lips and perioral soft tissue after bracket removal. Methods: The sample used in this study was 19 males and 33 females. Cephalometric X-rays were taken at 3 stages - T1 (before debonding), T2 (just after debonding), T3 (1.5 months after debonding). Results: The lower lip was retruded immediately after debonding (T2-T1), and 1.5 months after debonding (T3-T2). The mean amounts of retrusion from the vertical reference plane (sG perpendicular line) were about 0.38 mm for the upper lip and 0.88 mm for the lower lip. Immediately after debonding, lip retrusion of females was greater than that of males. During the post-debonding period, lower lip of males was retruded more than that of females. Conclusion: Lips are retruded after bracket removal, and there is no gender difference 1.5 months after debonding.

• Journal of Korea Port Economic Association
• /
• v.39 no.2
• /
• pp.129-141
• /
• 2023

This study analyzes the dynamic characteristics of daily freight rates of dry bulk and tanker shipping markets and their forecasting accuracy by using the error correction models. In order to calculate the error terms from the co-integrated time series, this study uses the common stochastic trend model (CSTM model) and vector error correction model (VECM model). First, the error correction model using the error term from the CSTM model yields more appropriate results of adjustment speed coefficient than one using the error term from the VECM model. Furthermore, according to the adjusted determination coefficients (adjR²), the error correction model of CSTM-model error term shows more model fitness than that of VECM-model error term. Second, according to the criteria of mean absolute error (MAE) and mean absolute scaled error (MASE) which measure the forecasting accuracy, the results show that the error correction model with CSTM-model error term produces more accurate forecasts than that of VECM-model error term in the 12 cases among the total 15 cases. This study proposes the analysis and forecast tasks 1) using both of the CSTM-model and VECM-model error terms at the same time and 2) incorporating additional data of commodity and energy markets, and 3) differentiating the adjustment speed coefficients based the sign of the error term as the future research topics.

• The korean journal of orthodontics
• /
• v.11 no.2
• /
• pp.135-142
• /
• 1981

This study was performed to observe the gross reactions of surrounding maxillary sutures to the widening of midpalatal suture in the dog. Three healthy dog were chosen for the experiment. One animal was used as control, and two were used as experimental animals. Midpalatal suture was expanded total 7mm with screw for 10 days. The following results were obtained : 1. Midpalatal suture was expanded with the most width, in which anterior was be more expanded than the posterior, and shape was wedge form. 2. Interincisive suture was definitely expanded. 3. Internasal suture and interfrontal suture were slightly expanded. 4. Expansion of frontomaxillary suture, frontoparietal suture, frontonasal suture, zygomatico temporal suture, zygomatico frontal suture, zygomatico maxillary suture, occipito mastoid suture, occipito parietal suture, naso incisive suture, naso maxillary suture, and incisive maxillary suture were not observed.