• 한국컴퓨터그래픽스학회논문지
• /
• 제17권2호
• /
• pp.45-53
• /
• 2011

본 논문에서는 양질의 이면각을 가진 사면체로 물체 내부를 채우는 볼륨 요소망 구성 방법을 제안한다. 본 논문에서 제안한 방법은 실행시간이 빠르고 안정적이며 구현이 쉬운 장점을 가지고 있다. 효율적인 공간 활용을 위해 옥트리를 사용함으로써 물체 내부에서 표면에 이르기까지 다양한 크기의 사면체를 활용할 수 있다. 최소 이면각을 최대화하고 최대 이면각을 최소화하는 양질의 요소망을 얻기 위하여 옥트리의 인접 셀들 사이의 레벨 차이를 제한하며, 옥트리 및 요소망 생성 속도를 높이기 위하여 정규 격자에서의 부호거리장을 사용한다. 본 논문에서 제안한 요소망 구성 방법은 유한요소법 기반의 변형체 시뮬레이션이나 사면체 기반의 유체 시뮬레이션 등에서 유용하게 활용될 수 있다.

• 전자공학회논문지
• /
• 제49권11호
• /
• pp.141-148
• /
• 2012

Oversampling 기법을 사용한 analog-to-digital (A/D) 컨버터에서 샘플링 된 신호의 signal bandwidth를 낮추어 주기 위해 데시메이션 필터가 사용된다. 본 논문은 sigma-delta ADC에 사용될 수 있는 저전력 4 단 32 bit 데시메이터 필터 디자인을 제안한다. 디지털 데시메이션 필터는 CIC(cascaded integrator-comb) filter와 세 개의 half-band FIR filter로 이루어져 있다. 전력소모를 최소화하기 위하여 CIC filter에는 pipeline구조가 사용되었고, FIR 필터의 multiplier 구조를 최적화하기 위하여 Canonic Signed Digit (CSD) 코드가 사용되었다. 130nm CMOS 공정으로 설계 자동화 CAD 도구를 사용하여 타이밍, 면적, 전력소모를 최적화하여 98.304 MHz 주파수에서 697 uW의 전력을 소모면서 32 bit, 192 kHz 아웃풋을 낼 수 있다.

• 대한중풍순환신경학회지
• /
• 제6권1호
• /
• pp.45-53
• /
• 2005

Objective : This study was performed to examine the relationship between cerebral blood vessel with meridian by using Transcranial Doppler Ultrasonography(TCD) Method : Monitoring of TCD was examined in 10 healthy people in their twenties (mean age was 26.5±1.00). Each examination was performed before & after acupuncture. Three Meridian were tested. Those were Stomach Meridian, Bladder Meridian & Gallbladder Meridian. Maximum velocity and Mean velocity were analyzed from TCD on different vessel. Result : The results showed significant(p<0.05; Wilcoxon signed rank test) change in some cerebral blood flow after acupuncture. Conclusion : There was the relationship between Meridian and cerebral blood vessel.

• 한국산업보건학회지
• /
• 제26권3호
• /
• pp.324-333
• /
• 2016

Objectives: We aimed to compare the sampling performance of different flow-based impactor samplers for collecting fungal spores and bacteria and to explore the association of the level of bioaerosols with activity patterns of occupants in daycare center settings. Methods: For comparison of sampling performance, two different flow-based samplers (greater than 100 L/min or not) were selected; a low flow-based sampler (one-stage Andersen sampler) and two high flow-based samplers (DUO SAS SUPER 360 sampler, BUCK bio-culture sampler). We collected airborne mold and bacteria in 30 daycare centers with various levels of contaminated air. Three repeat samplings per each sampler were performed. Mold and bacteria were grown for 96 hours at $25{\pm}1^{\circ}C$ and 48 hours at $35{\pm}1^{\circ}C$, respectively. The Andersen and SAS samplers were used for investigating the association between the level of bioaerosols and the activity patterns of occupants in daycares. Particular matters 10($PM_{10}$), temperature, and relative humidity were monitored as well. Samplings were carried out with one-hour interval from 9 to 5 O'clock. For statistical comparisons, Kruskal-Wallis test, Wilcoxon's signed rank test, and multiple regression analysis were carried out. Results: The airborne level of molds by the low flow-based sampler were significantly higher than that of high flow-based samplers (indoor, P=0.037; outdoor, P=0.041). However, no statistical difference was observed in the airborne level of bacteria by each sampler. Also the level of bioaerosols varied by the time, particularly with different activity patterns in daycare centers. The higher level of mold and bacteria were observed in play time in indoor. Similarly, the concentrations of $PM_{10}$ were significantly associated with the level of bioaerosols (P<0.05). Conclusions: Our findings indicate that the flow rate of sampler, rather than total air volume, could be able to affect the results of sampling. Also, the level of airborne mold and bacteria vary behavior patterns of occupants in indoor of daycare settings. Therefore, different samplers with other flow rate may be selected for mold or bacteria sampling, and activity patterns should be considered for bioaerosol sampling as well.

• Journal of Acupuncture Research
• /
• 제18권6호
• /
• pp.105-113
• /
• 2001

Objective : This study was performed to evaluate the effect of acupuncture on cerebral blood flow by Transcranial Doppler Ultrasonography(TCD) Method : Monitoring of TCD was examined in 11 healthy women volunteer(mean $age:\;24.5{\pm}2.9\;\;years$) before, during and after acupuncture on Paekoe(GV20). Mean velocity, pulsatility index, systolic velocity and diastolic velocity values are analyzed from DWL. MDX4 at different depths of both middle cerebral artery. Results : The results showed a significant(p<0.05; Friedman test & Wilcoxon signed ranks test) increase in mean velocity, systolic velocity and diastolic velocity decrease in pulsatility index, which was measured at different depths of both middle cerebral artery. Conclusion : These results suggest that acupuncture could have a specific effect on cerebral blood flow.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제9권4호
• /
• pp.285-291
• /
• 2004

A simulated moving bed (SMB) chromatography system is a powerful tool for preparative scale separation, which can be applied to the separation of chiral compound. We have de-signed our own lab-scale SMB chromatography using 5 HPLC pumps, 6 stainless steel columns and 4 multi-position valves, to separate a racemic mixture of ketoprofen in to its enantiomers. Our design has the characteristics of the low cost for assembly for the SMB chromatography and easy repair of the unit, which differs from the designs suggested by other investigators. It is possible for the flow path through each column to be independently changed by computer control, using 4 multi-position rotary valves and 5 HPLC solvent delivery pumps. In order to prove the operability of our SMB system, attempts were made to separate the (S)-ketoprofen enantiomer from a ketoprofen racemic mixture. The operating parameters of the SMB chromatography were calculated for ketoprofen separation from a batch chromatography experiment as well as by the triangle theory. With a feed concentration of 1 mg/mL, (S)-ketoprofen was obtained with a purity of 96% under the calculated operating conditions.

• 품질경영학회지
• /
• 제50권2호
• /
• pp.251-264
• /
• 2022

Purpose: This study aims to contribute to the research flow on the relationship between win-win supportive collaboration and safety, while noting that win-win supportive collaboration affects corporate safety-related factors such as climate, safety prevention, and behavior from the perspective of domestic small and medium-sized logistics companies that have signed contracts with large logistics companies, Methods: Based on responses from 147 small and medium-sized logistics companies, structural equation modeling is performed to examine the relationship among the factors such as supportive collaboration, safety climate, safety prevention, safety behavior. Results: Study results are as follows. Supportive collaboration of large logistics companies influence the formation of a safety climate and safety behavior within logistics SMEs positively. In addition, safety prevention and safety behavior are affected by safety climate in a positive way. Conclusion: Win-Win supportive collaboration is a driving force behind safety management practices in the supply chain leading to safety management performance, so it is necessary to consider it for the growth of the sustainable supply chain.

• 대한전자공학회논문지TC
• /
• 제39권7호
• /
• pp.30-37
• /
• 2002

본 논문에서는 무선 ATM 망에서 VBR(Variable Bit Rate) 트래픽의 QoS(Quality of Service)를 보장하고 무선 채널의 효율성을 극대화 할 수 있는 새로운 적응적 슬롯 할당 알고리즘인 In-VDSA를 제안한다. 제안된 알고리즘에서는 ATM 셀 헤더 부분의 GFC(Generic Flow Field) 필드 상에 단말기의 버퍼 상태를 부호화하여 piggybacking하는 방식을 채택하였으며 다음 프레임에 할당할 슬롯의 개수를 기존의 다른 방식과는 달리 유동적으로 조절하여 할당함으로써 단말기의 셀 손실이나 지연에 대한 QoS를 보장하고 채널 이용 효율을 높일 수 있었다. 제안된 알고리즘은 BONeS tool을 이용한 시뮬레이션을 통하여 기존의 방식과 비교 분석한 결과 그 정당성을 확인하였다.

• Investigative Magnetic Resonance Imaging
• /
• 제11권2호
• /
• pp.87-94
• /
• 2007

목적: 3T 장비의 신생아 뇌자기공명영상에서 T1 강조 고속 역전회복기법 (fast inversion recovery, FIR)과 자기화 삼차원 경사에코기법, (magnetization-prepared three dimensional gradient echo sequence, 3D GRE)을 스핀에코기법 (SE)과 비교하여 유용성을 알아보는 데 있다. 대상 및 방법: 20명의 신생아에서 T1 강조 SE, FIR, 그리고 3D GRE의 신호소음비 (SNR)와 대조소음비 (CNR)를 측정하고 시각적으로 회백질-백질 구별, 수초화 인식, 인공음영 발생을 점수화하여 비교하였다. 각 영상기법의 CNR 비교에는 Wilcoxon signed ranked test를 사용하였다. 결과: 세가지 영상기법 중 3D GRE가 가장 우수한 SNR을 보였고 CNR은 FIR과 3D GRE 모두 SE보다 우수하였으며 FIR보다 3D GRE가 더 우수하였다. 회백질-백질의 구분과 수초화 유무 역시 스핀에코보다 FIR과 3D GRE에서 더 잘 보였다. 그러나 3D GRE는 움직임에 의한 인공음영이 많았고 FIR에서 혈류에 의한 혈관의 고신호강도가 자주 발견되었다. 결론: 3T 장비에서 신생아 뇌영상을 얻을 때 FIR과 3D GRE 기법은 SE보다 좋은 T1 강조영상을 제공할 것으로 기대된다.

• Restorative Dentistry and Endodontics
• /
• 제26권1호
• /
• pp.16-22
• /
• 2001

The purpose of this study was to evaluate the marginal microleakage of condensable composite resin restorations according to flowable resin lining of internal cavity wall. The eighty extracted human molar teeth without caries and/or restorations are used The experimental teeth were randomly assigned into four groups of ten teeth each. Eighty caries-free extracted human molars were used in this study. The conventional class II cavities (box-shaped on mesial and distal surface, faciolingual width : 3mm, gingival wall depth : 1.5mm) were prepared 1mm below cementoenamel junction with a # 701 carbide bur. The teeth were divided into four groups, and then each group were subdivided into A & B group according to flowable resin & compomer lining ; Group 1-A : Tetric Ceram filling, Group 1-B : Tetric Flow lining and Tetric Ceram filling, Group 2-A Ariston pHc filling, Group 2-B : Tetric Flow lining and Ariston pHc filing, Group 3-A SureFil filling, Group 3-B : Dyract Flow lining and SureFil filling, Group 4-A : Pyramid filling, Group 4-B : Aeliteflo lining and Pyramid filling. To simulate as closely as possible the clinical situation during retoration placement, a "restoration template" was fabricated, and the condensable resin was filled using a three-sited light-curing incremental technique. All the materials used were applied according to the manufacturers' instructions. The specimens were stored in the 100% humidity for 7 days prior to thermocycling (100 thermal cycles of 5~55$^{\circ}C$ water with a 30-second dwell time) The specimens were immersed in 2% metyleneblue dye for 24 hours, and then embedded in transparent acrylic resin and sectioned mesiodistally with diamond wheel saw. The degree of marginal leakage was scored under stereomicroscope ($\times$20) and the data were analyzed by Kruskal-Wallis test and Wilcoxon signed ranks test. The results were as follows : 1. In the gingival margins of all the group, microleakage of subgroup B was less than subgroup A. 2. In the group 1, 2, 4, there was significant differences between subgroup A and B (p<0.05), but in the group 3, there was not significant different between group 3-A (SureFil) and group 3-B (Dyract flow/SureFil) (p>0.05). 3. In the subgroup A and B, there was significant different between all group except group 4 of subgroup A. From the results above, it was suggested that the cavity lining of flowable resin and flowable compomer in condensable resin restoration decrease microleakage at gingival margin, and does improve their ability to seal the gingival margin of class II preparation.