광대역 파장가변 이중 링 공진기 Add/Drop 필터

이동현,이태형,박준오,김수현,정영철,Lee, Dong-Hyun,Lee, Tae-Hyung,Park, Joon-Oh,Kim, Su-Hyun,Chung, Young-Chul 한국광학회 2007 한국광학회지 Vol.18 No.3

본 논문에서는 굴절률 차이가 큰 폴리머 광 도파로를 이용하여 광대역 파장가변이 가능한 이중 링 공진기 Add/Drop 필터를 제작하였다. Add/Drop 필터의 제작시 공정 오차에 둔감한 특성을 갖도록 광 결합기를 설계하였다. 코어와 클래딩의 굴절률은 1550 nm 파장 대역에서 각각 1.51, 1.378로 약 $100{\mu}m$ 정도의 곡률 반경을 가지는 곡선 도파로를 수용할 수 있다. 두 개의 링이 동시에 공진하는 파장 대역에서 Drop 특성은 이웃하는 피크 좌다 약 2.9 dB 이상 높은 특성을 보였다. 이 필터는 반사형 반도체 광증폭기 등과의 하이브리드 집적을 통하여 광대역 파장 가변 레이저 다이오드를 구현하는데 활용할 수 있을 것으로 기대된다. A widely tunable add/drop filter composed of double ring resonators is implemented with high-index-contrast polymer waveguide. To enhance the productivity, directional couplers are designed to have good fabrication tolerance. The refractive indices of the core and cladding in the 1550 nm wavelength are 1.51 and 1.378, respectively. Drop response in comparison with neighborhood peak gets enhanced by more than 2.9 dB at the wavelength where both rings resonate. This filter can be used to build widely tunable laser diode through hybrid-integration with reflective SOA.

하악 전돌증 환자에서 전산화 단층 촬영을 이용한 하악관의 해부학적 위치에 관한 연구

이동현,김재원,이수연,김재현,안상헌,이상한,장현중,Lee, Dong-Hyun,Kim, Jae-Won,Lee, Su-Youn,Kim, Jae-Hyun,An, Sang-Heon,Lee, Sang-Han,Jang, Hyun-Jung 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.6

Purpose: In this study, we analyzed and compared the anatomical position of the mandibular canal in normal occlusion and mandibular prognathism patients. Patients and Methods: Computed tomography image from 58 patients were divided into normal occlusion group and mandibular prognathism group, and each measurement were taken in the each measuring points(2nd premolar, 1st molar, 2nd molar, 3rd molar, ramus). Measurements were statistically analyzed by student's t-test. Results: BC (Thickness of the buccal cortex) value was 2.3~2.7 mm, CB (Distance from the canal to the lingual aspect of the buccal cortex) value was 1.3~4.3 mm, MC (Diameter of the canal) value was 3.2~3.8 mm, LI (Distance from the canal to the lingual aspect of the lingual cortex) value was 2.0~3.7 mm, TM (Thickness of the total mandible) value was 9.5~12.9 mm and CM (Distance from the canal to the inferior border of the mandible) value was 6.9~17.5 mm. Conclusion: In the comparison between two groups, there was statistically significant difference in CB value of 2nd, 3rd molar between normal occlusion and mandibular prognathism, and other value in the rest of the measuring points didn't show statistically significant difference.

소결 온도에 따른 0.98(Na_0.5K_0.5)NbO₃-0.02Li(Sb_0.17Ta_0.83)O₃+0.01wt%ZnO 세라믹스의 압전 특성

이동현,이승환,이성갑,이규탁,이영희,Lee, Dong-Hyun,Lee, Seung-Hwan,Lee, Sung-Gap,Lee, Ku-Tak,Lee, Young-Hie 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.7

We studied sintering temperature to enhance the piezoelectric properties of $0.98(Na_{0.5}K_{0.5})NbO_3-0.02Li(Sb_{0.17}Ta_{0.83})O_3$+0.01wt%ZnO (hereafter NKN-LST+ZnO) lead free piezoelectric ceramics. The synthesis and sintering method were the conventional solid state reaction method and sintering was executed at $1,080\sim1,120^{\circ}C$. We found that NKN-LST+ZnO ceramics at optimal sintering temperature showed the improved piezoelectric properties at the optimal sintering temperature. The NKN-LST+ZnO ceramics show good performance with piezoelectric constant $d_{33}$= 153 pC/N sintered at $1,090^{\circ}C$. The results reveal that NKN-LST+ZnO ceramics are promising candidate materials for lead-free piezoelectric application.

대학 공시정보를 활용한 교육국제화역량 인증 여부 예측: 이산선택모형에 의한 대학알리미 공시정보 분석

이동현(Lee, Dong-hyun),조순정(Cho, Soon-jeong) 한국경영교육학회 2020 경영교육연구 Vol.35 No.3

[연구목적] 본 연구는 대학 공시정보를 활용하여 교육국제화역량 인증(IEQAS) 여부를 예측하며, 대학의 인증 유지를 위한 자가 점검에 적합한지 연구 모형을 검증하는데 목적이 있다. [연구방법] 동 연구는 IEQAS 인증․미인증 예측을 위해 2019년 대학알리미 웹사이트에 공개된 138개 사립 대학의 공시정보를 수집했다. 이어, 인증 대학 77개교 및 미인증 대학 61개교 두 집단 간 지표 차이를 검정 후, 5개의 대학경쟁력지표 및 9개의 재정회계지표를 독립 변수로, 2019년 3월에 발표된 IEQAS 인증 결과를 이산형 종속 변수로 설정하여 이산선택모형에 따라 로짓분석과 판별분석을 하였다. [연구결과] 본 연구자들은 t-검정으로 선별한 재학생충원율/신입생충원율/전임교원확보율(이상 대학경쟁력), 학생1인당교육비/교육비환원율/부채비율/법인전임급비율(이상 재정회계)을 연구 모형에 유의한 요인으로 투입했다. 그 결과, 대학경쟁력 지표를 통한 예측력은 로짓분석 71.7%, 판별분석 71.0%로, 재정회계 지표의 경우 로짓분석 70.3%, 판별분석 66.7%의 예측력을 보였다. 동 이산선택모형 내에 공통으로 관여한 유의미한 변수는 재학생충원율, 신입생충원율과 학생1인당교육비로 나타났다. [연구의 시사점] 동 연구는 조직의 부실 여부 예측에 유용한 로짓분석과 판별분석을, 정부의 대학별 공개 자료를 활용하여 IEQAS 인증․미인증 예측에 적용해 본 가치를 지닌다. 본 연구의 이산선택모형은 타당성과 신뢰성이 확인됨으로써, 대학이 손수 IEQAS 인증 유지 점검 시 활용할 수 있으며 대학 평가에 관한 경영교육 실무에 기여할 것이다. [Purpose] Based on a discrete choice model(DCM), this study aims to predict the ‘pass/fail’ of the International Education Quality Assurance (IEQAS) by analyzing publicly opened dataset. Thus, it will enable Korean universities to self-test their IEQAS-related capabilities in a productive manner. [Methodology] This work utilized disclosed data on academyinfo.go.kr in 2019, including a total of 138 private universities from My university competitiveness(MUC), Financial accounting index(FAI); relying on related literature, it proposed two hypotheses and 14 independent variables, followed by conducting logit analysis(LA) and discriminant analysis(DA). [Findings] First, t-tests identified three MUC variables(Levy with enrolled students; Levy with new students; Faculty in full service) and four FAI variables(Educational expenditure; Educational restitution rate; Liability ratio; Corporate transferred money) between 77 IEQAS ‘pass’ group and 61 IEQAS ‘fail’ group in 2019. This DCM presented the following predictive powers: 71.7%-LA vs 71.0%-DA in MUC and 70.3% -LA vs 66.7%-DA in FAI, while Levy with enrolled students, Levy with new students and Educational expenditure worked as keys to predicting the ‘pass/fail’. [Implications] The DCM combining LA/DA can be used for both scholars on the business education area and the IEQAS-related practitioners.

하악 측방운동시 평형측 과두의 운동 궤적에 관한 컴퓨터 분석

이동현,최대균,박남수,Lee Dong-Hyun,Choi Dae-Gyun,Park Nam-Soo 대한치과보철학회 1993 대한치과보철학회지 Vol.31 No.4

The purpose of this study was to research the condylar path and the anterior angle of glenoid fossae and classify the patterns of condylar path. Thirty male and female dental students with normal occlesion and masticatory system ranging in age from 21 to 30, without present symptoms and an)r history of TM joint disturbance, were selected for this study. Transcranial radiographs of TM joints under mandibular lateral movement were obtained. By the computer analysis on the radiographs, the angle of posterior slope of articular eminance, the sagittal condylar guidance angie, condylar movement patterns and the height of glenoid fossa was measured respectively, and studied their interrelationship comparatively. The results obtained were as follows : 1. The total distance of condylar movement on balancing side during mandibular lateral movement was 4.55mm for Lt. and 4.78mm for Rt. when mandible moved from C.R. to canine to canine relation and 7.86mm for the Lt. and 8.10mm for the Rt. when mandible moved from C.R. to 7.5mm. 2. The horizontal distance of condylar movement on balancing side during mandibular lateral movements was 3.16mm for the Lt. and 3.52mm for the Rt. when mandible moved from C.R. to canine to canine relation and 6.10mm for the Lt. and 6.30mm for the Rt. when mandible moved from C.R. to 7.5mm. 3. The sagittal condylar guidance angle on balancing side during mandibular lateral movements was $45.96^{\circ}$ for the Lt. and $43.22^{\circ}$ for the Rt. when mandible moved from C.R. from canine to canine relation and $41.14^{\circ}$ for the Lt. and $39.77^{\circ}$ for the Rt. when mandible moved from C.R. to 7.5mm. 4. The height of glenoid fossa was 8.23mm for the Lt. and 7.80mm for the Rt. and the angle of posterior slope of articular eminence was $38.30^{\circ}$ for the Lt. and $38.79^{\circ}$ for the Rt. by method-A and $55.61^{\circ}$ for the Lt. and $55.64^{\circ}$ for the Rt. by method-B. 5. The sequence of the frequency of condylar movement patterns on balancing side during mandibular lateral movement were concave type(30 cases), convex type(16 cases), reverse S shape curve(9 cases) and S shape curve(5 cases) when mandible moved from C.R. to canine to canine relation and concave type(27 cases), 5 shape curve(13 cases), convex type(11 cases) and reverse S shape curve(9 cases) when mandible moved from C.R. to 7.5mm.

심층 컨벌루션 신경망 기반의 실시간 드론 탐지 알고리즘

이동현,Lee, Dong-Hyun 한국로봇학회 2017 로봇학회 논문지 Vol.12 No.4

As drones gain more popularity these days, drone detection becomes more important part of the drone systems for safety, privacy, crime prevention and etc. However, existing drone detection systems are expensive and heavy so that they are only suitable for industrial or military purpose. This paper proposes a novel approach for training Convolutional Neural Networks to detect drones from images that can be used in embedded systems. Unlike previous works that consider the class probability of the image areas where the class object exists, the proposed approach takes account of all areas in the image for robust classification and object detection. Moreover, a novel loss function is proposed for the CNN to learn more effectively from limited amount of training data. The experimental results with various drone images show that the proposed approach performs efficiently in real drone detection scenarios.

PRMS: Page Reallocation Method for SSDs

이동현,노홍찬,박상현,Lee, Dong-Hyun,Roh, Hong-Chan,Park, Sang-Hyun Korea Information Processing Society 2010 정보처리학회논문지D Vol.17 No.6

Solid-State Disks (SSDs)는 빠른 접근 시간, 적은 전력소모, 전기 충격에의 내성과 같은 장점으로 인해 하드 디스크를 대체 할 것으로 기대되고 있다. 그러나 SSDs는 임의 쓰기(random write)로 인한 수명 단축이란 단점이 있으며 이는 SSDs 컨트롤러의 구조와는 별개로 나타나고 있다. SSDs와 관련한 기존 연구는 컨트롤러의 더 나은 디자인과 쓰기 연산의 감소에 주력하였다. 본 연구는 동시에 쓰여지는 경향이 있는 여러 데이터 페이지를 연속적인 블록에 배치하는 방법을 제시한다. 이 방식은 우선 특정 기한 동안 쓰기 연산에 대한 정보를 수집한 후 상기 쓰기 연산에 대한 정보를 트랜잭션화 하여 frequent itemset을 추출하고 이를 연속적인 블록에 재배치하는 과정으로 이루어진다. 또한 본 연구는 frequent itemset의 page를 재배치할 수 있는 알고리즘을 소개한다. TPC-C 기반 실험에 있어 본 연구가 제안한 재배치를 수행한 결과 저장 기기 접근 횟수를 평균 6 % 감소시킬 수 있었다. Solid-State Disks (SSDs) have been currently considered as a promising candidate to replace hard disks, due to their significantly short access time, low power consumption, and shock resistance. SSDs, however, have drawbacks such that their write throughput and life span are decreased by random-writes, nearly regardless of SSDs controller designs. Previous studies have mostly focused on better designs of SSDs controller and reducing the number of write operations to SSDs. We suggest another method that reallocates data pages that tend to be simultaneously written to contiguous blocks. Our method gathers write operations during a period of time and generates write traces. After transforming each trace to a set of transactions, our method mines frequent itemsets from the transactions and reallocates the pages of the frequent itemsets. In addition, we introduce an algorithm that reallocates the pages of the frequent itemsets with moderate time complexity. Experiments using TPC-C workload demonstrated that our method successfully reduce 6% of total logical block access.

퇴비단 여과재 구성에 따른 혐기소화액 여과 효과

이동현,정광화,김중곤,곽정훈,안희권,김은종,Lee, Dong-Hyun,Jeong, Kwang-Hwa,Khan, Modabber Ahmed,Kim, Jung-Gon,Kwak, Jung-Hun,Ahn, Heekwon,Kim, Eun-Jong 한국축산환경학회 2013 한국축산시설환경학회지 Vol.19 No.1

This study was carried out to compare the filtration effect of anaerobic digestion waste water by compost filtration bed. Three types of filtration systems were set for filtration test following to composition of bedding materials. Two filtration systems were filled with sawdust, rice-hull and wood-chip. And the other was filled with sawdust and rice-hull. Anaerobic digestion waste water was applied evenly on the surface of the filtration bed with spraying nozzle. The concentration of nitrogen, biochemical oxygen demand (BOD), suspended solids (SS) of anaerobic digestion waste water was decreased by filtration treatment. The total nitrogen content was decreased from 1,313 mg/L to 1,090~1,293 mg/L and BOD concentration was decreased from 529.7 mg/L to 125~162.3 mg/L, respectively. The SS content was decreased from 69~79% by filtration process. In addition, the electrical conductivity (EC) was decreased from 10.22 ds/m to 7.91~8.31 ds/m.

침전법으로 제조된 Mg(OH)₂의 잔류 Na염이 MgO 입자 형성에 미치는 영향

이동현,유승범,김대성,임형미,이승호,Lee, Dong-Hyun,Ryu, Seung-Bom,Kim, Dae-Sung,Lim, Hyung-Mi,Lee, Seung-Ho 한국재료학회 2012 한국재료학회지 Vol.22 No.1

The particle size of MgO was examined as a function of the Na content in $Mg(OH)_2$ powders and the calcination temperature. $Mg(OH)_2$ suspension was obtained by dropwise precipitation of $Mg(NO_3)_2{\cdot}6H_2O$ and NaOH solutions. The suspension was diluted by varying the dilution volume ratio of distilled water to $Mg(OH)_2$ suspension to change the Na salt concentration in the suspension. $Mg(OH)_2$ slurry was filtered and dried at $60^{\circ}C$ under vacuum, and then its $Mg(OH)_2$ powder was calcined to produce MgO with different amount of Na content at $500\sim900^{\circ}C$ under air. Investigation of the physical and chemical properties of the various MgO powders with dilution ratio and calcination temperature variation was done by X-ray diffraction, transmission electron microscopy, BET specific surface area and thermal gravimetric analysis. It was observed that MgO particle size could depend on the condition of calcination temperature and dilution ratio of the $Mg(OH)_2$ suspension. The particle size of the MgO depends on the Na content remaining in the $Mg(OH)_2$ powder, which powder was prepared by changing the dilution ratio of the $Mg(OH)_2$ suspension. This change increased as the calcination temperature increased and decreased as the dilution ratio increased. The growth of MgO particle size according to the increase of temperature was more effective when there was a relatively high content of Na. The increase of Na content lowered the temperature at which decomposition of $Mg(OH)_2$ to MgO took place, thereby promoting the crystal growth of MgO.

인삼양위탕(人蔘養胃湯)이 위장관(胃腸管)에 미치는 영향(影響)

이동현,김덕곤,정규만,Lee Dong-Hyun,Kim Deog-Gon,Jeong Gyu-Mann 대한한방소아과학회 1986 대한한방소아과학회지 Vol.1 No.1

Although the Insamyangwee-Tang has been widely used in clinical purposes in the oriental medicine and its clinical efficiency is documented for the cases of gastritis, gastric ulcer and enteritis but the experimental study on these has not been undertaken. So,To investigate the clinical efficiency, of Insamyangwee-Tang and validate its oriental medical theory, these experiments were undertaken, by being compared with animal experiment. ?The following results were obtained. ?1. By effect of Insamyangwee-Tang on isolated ileum from mice, rats, rabbits and Guinea pigs, the motility of ileums was inhibited remarkably. ?2. By effect of Insamyangwee-Tang on motility of the small intestine in rabbits, the motility was inhibited remarkably too. ?3. Insamyangwee-Tang inhibited charcoal transport functions in the small intestine of mice. ?4. By effect of Insamyangwee-Tang on isolated duodenum from rats, the motility of duodenum was inhibited remarkably.?5. Gastric juice and pepsin secretion was decreased, anti-ulceration effect was recognized.