• 한국정보통신학회논문지
• /
• 제26권7호
• /
• pp.1032-1039
• /
• 2022

이동통신 중계기에 사용하는 SAW(Surface Acoustic Wave) 방식의 대역통과필터를 대체할 수 있는 5G 이동통신 중계기용 군 지연 특성이 개선된 크로스 커플링 등화기 구조를 결합한 캐비티 대역통과필터를 설계하고 이를 구현하였다. 3D EM 시뮬레이션 툴 (HFSS)을 이용하여 공진 주파수, 공진기 간 결합 계수와 공진기 사이 외부 품질 계수를 계산하였고, 이를 바탕으로 메탈 캐비티 구조로 주파수대역 3500MHz~3600MHz, 대역폭 97.85MHz로 대역 양쪽 가장자리 주파수(edge)단에서 20dB 이상의 감쇄 특성을 가지도록 12차 대역 통과 필터를 제작 하였다. 설계 제작한 대역통과필터는 5G 이동통신 표준에 요구하는 군 지연 시간 조건과 인-밴드, 아웃-밴드 주파수 응답을 만족하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.34-40
• /
• 2001

Aeroacoustic technology to improve the acoustic comfort in high-speed became a major topic in vehicle development process. Although most of wind noise reduction and sound quality improvements are possible with full vehicle, the countermeasures should be applied at the early design stage. Acoustic holography technology was used to identify the external wind noise sources of a vehicle in Hyundai Aeroacoustic Wind Tunnel. Microphone self-noise reduction techniques and several reference microphone positions are investigated in order to obtain proper results.

• Advances in pediatric surgery
• /
• 제9권1호
• /
• pp.52-56
• /
• 2003

A 10 year old boy was admitted with blunt abdominal trauma by bike handle injury. The patient was operated upon for a generalized peritonitis due to pancreaticoduodenal injury. On opening the peritoneal cavity. complete transection of distal end of common bile duct and. partial separation between pancreas head and second portion of duodenum were found. Ligation of the transected end of the common bile duct. T-tube choledochostomy, and external drainage were performed. A pseudocyst was found around the head portion of the pancreas on the 7th postoperative day with CT. An internal fistula had developed between the pseudocyst and ligated common bile duct. The pseudocyst was subsided after percutaneous drainage. In the case of the undetermined pancreatic injury, percutaneous external drainage can be effective in treating the traumatic pancreatic pseudocyst in a pediatric patient.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.9-12
• /
• 2000

Insulators for high-voltage and large-power should be endured mechanically the weight of mold bushing itself and the force of pushed from contact with circuit breaker and conductor. But dielectric breakdown could be occurred result from the external circumstances and internal factors such as chemical reaction, partial discharge, change of temperature and the relation of temperature-time in process of casting. Therefore, to get rid of external and internal factors of dielectric breakdown. Furthermore, to prevent the internal cracks, void, cavity which resulted from the contraction originated on the interface between copper and epoxy resin, formed semi-conductive layer with partially carbon painted on copper bar. The PD properties and the insulation qualities of epoxy molded insulators were improved by roles of cushions for the direction of diameter and natural sliding effects as like separated from conductor for the direction of length.

• Journal of the Korean Physical Society
• /
• 제73권11호
• /
• pp.1663-1674
• /
• 2018

We propose the Poynting vector analysis of the air mode in a top-emitting organic light-emitting diode (OLED) by combining the transfer matrix method and dipole source term. The spatial profiles of the time-averaged optical power flow of the air mode are calculated inside and outside the multilayer structure of the OLED with respect to the thickness of the semi-transparent top cathode and capping layer (CPL). We elucidate how the micro-cavity effect controlled by the thickness variation of the semi-transparent top cathode or CPL affects the internal optical power and absorption loss inside the OLED multilayer and the external optical power coupled into the air. When the calculated absorption loss and external power obtained by the proposed Poynting vector and currently-used point dipole models are compared, two calculation results are identical, which demonstrates the validity of the two models.

• Journal of Species Research
• /
• 제11권2호
• /
• pp.102-107
• /
• 2022

The order Nudibranchia Cuvier, 1817 is among the most colorful gastropod group that lacks an external shell and mantle cavity at their adult stage. They are widely found in the intertidal to subtidal zones of marine habitats worldwide. To date, a total of 58 species are known from Korean waters. In this study, we report seven nudibranch species that are newly reported from Korean waters and provide their color images of external body, morphological description, taxonomic remarks, and mtDNA cox1 barcode sequence information: Dendronotus primorjensis Martynov, Sanamyan & Korshunova, 2015; Doto japonica Odhner, 1936; Trinchesia ornata (Baba, 1937); Antiopella fusca (O'Donoghue, 1924); Cadlina paninae Korshunova, Fletcher, Picton, Lundin, Kashio, N. Sanamyan, K. Sanamyan, Padula, Schrodi & Martynov, 2020; Rostanga bifurcata Rudman & Avern, 1989; and Goniodoridella savignyi Pruvot-Fol, 1933.

• 한국압력기기공학회 논문집
• /
• 제19권1호
• /
• pp.36-43
• /
• 2023

Lots of researches have been conducted on in-vessel retention (IVR) to prevent or mitigate severe accident in nuclear power plants. Various methodologies were proposed and the external reactor vessel cooling was selected as a part of promising IVR strategy. In this study, the strategy is strengthened by enhancing the natural circulation performance through the adoption of insulation in the reactor cavity. A thermal analysis was carried out based on an assumed accident scenario and its results were used as boundary conditions for subsequent seven flow analysis cases. By comparing the natural circulation performance, effects of annular gaps and insulation shapes on the mass flow rate and flow velocity were quantified. The improvement in cooling performance can be reflected in actual design via detailed assessment.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
• /
• pp.276.2-278
• /
• 2000

In a recent years, a number of approaches have been studied, including passive, active, and hybrid mode-locking of semi-conductor lasers for short pulse generation and research has been devoted to achieve low timing-jitter operation since the timing jitter is unfavorable for system applications. Among the methods of mode locking, passive mode locking does not need external rf drives, and therefore the operation and fabrication procedures are simplified. In spite of these attractive advantages of passive mode-locked laser, it has critical drawbacks such as large timing jitter and the difficulty in synchronization with external circuits. Their inherent large timing jitter value was shown to be suppressed to certain levels by means of hybrid mode-locking technique$^{(1)}$ , where the saturable absorber section was modulated by an external signal with the cavity round trip frequency. Furthermore, the subharmonic mode-locking (SHML) technique alleviates the restrictions of high speed driving electronics. It has been demonstrated experimentally$^{(1)}$ that the hybrid subharmonic mode-locking technique has lead to significant reduction of the timing jitter. (omitted)

• Restorative Dentistry and Endodontics
• /
• 제45권1호
• /
• pp.5.1-5.8
• /
• 2020

Objectives: The obturation quality of MTA, Biodentine, Total Fill BC root canal sealer (RCS), and warm gutta-percha (WGP) in teeth with simulated internal root resorption (IRR) was evaluated by using micro-computed tomography. Materials and Methods: Standardized IRR cavities were created using 40 extracted maxillary central incisor teeth and randomly assigned into 4 groups (n = 10). IRR cavities were filled with MTA, Biodentine, Total Fill BC RCS (bulk-fill form) and WGP + Total Fill BC RCS. Percentage of voids between resorptive cavity walls and obturation material (external void), and inside the filling materials (internal voids) were measured. Results: Total Fill BC sealer in the bulk-fill form presented significantly highest values of external and internal void percentages (p < 0.05). Biodentine showed a significantly lowest external void percentage (p < 0.05). WGP + Total Fill BC RCS presented significantly lower values of internal void percentages than all groups (p < 0.05), except Biodentine (p > 0.05). Conclusion: None of the filling materials were created void-free obturation in resorption cavities. Biodentine may favor its application in teeth with IRR over Angelus MTA and bulkfill form of Total Fill BC.

• 전자공학회논문지A
• /
• 제31A권10호
• /
• pp.79-86
• /
• 1994

Gain-guided broad-area single quantum well separate confinement heterostructure diode lasers have been fabricated from structures grown by metal organic vapor phase epitaxy. The active layer of the epi-structure is InGaAs emitting 962-965nm and the guiding layer GaAs. The channel width is fixed to 150${\mu}$m and the cavity length varys within the range of 300~800${\mu}$m. For uncoated LD's, the output power of 0.7W has been obtaained at a pulsed current level of 2A, which results about 60% external quantum efficiency. The threshold current density is 200A/cm$^{2}$ for the cavity lengths of 800.mu.m LD's. The stain effect upon the transparent current density has been observed. The internal quantum efficiency is expected to be 88% and the internal loss to be 18$cm^{-1}$. The beam divergence has been measured to be 7$^{\circ}$to lateral and 40$^{\circ}$to transverse direction. finally, 1.2W continuous-wave output power has been obtained at a current level of 2A for AR/HR coated LD's die-bonded on Cu heat-sink and cooled by TEC.