http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
김우현(Woo-Hyun Kim) 대한치과의사협회 2021 대한치과의사협회지 Vol.59 No.2
One of the main goals of restorative treatment is to establish a physiological periodontal environment and promote periodontal health maintenance. Crown contours affect periodontal health. Loe in 1965 and Socransky in 1970 showed that bacterial plaque was a direct cause of periodontal disease. O"leary in 1970 and Perel in 1971 demonstrated experimentally that crown contours can also affect gingival health. Several theories about crown contours came before it was found that dental plaques are the direct cause of gum disease and, therefore, are mostly hypothetical or simple opinions. Unfortunately, when discussing the shape of the prosthesis, there are still arguments that have no rationale (or weak), such as shape to obtain gum support or shape that becomes self-cleansing. I hope that readers would understand Crown contours better through a review of the dental literature.
김우현,왕국명,길경석,지홍근,Kim, Woo-Hyun,Wang, Guoming,Kil, Gyung-Suk,Ji, Hong-Keun 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.6
Most series arcs lead to electrical fires that cannot be interrupted by circuit breakers, because the arc's current is outside the breaker's operating range. In this paper, experiments were conducted on the detection and identification of series arcs to prevent electrical fires. Plugs and outlets specified in KS C 8305 were deteriorated to replicate arc faults commonly found in fields. The characteristics of series arcs resulting from various types of loose connections were determined by analyzing the frequency spectra and phase distributions of detected arc pulses. The results showed that the simulated arc defects used in this study were more similar to actual arc phenomena than the existing arc generator specified in UL 1699. In addition, loose connections, such as wire-wire, terminal-wire, and outlet-plug, can be identified by phases of $0^{\circ}$, $180^{\circ}$ and $360^{\circ}$, respectively. These phases can be detected by a band pass filter with a frequency range of 5~10 MHz, which can be used as the trip signal for circuit breakers.
Conventional composite resin과 사뭇 다른 flexible composite resin의 여러 임상 활용 예
김우현,Kim, Woohyun 대한심미치과학회 2020 Journal of the Korean Academy of Esthetic Dentistr Vol.29 No.2
Bond-Fill SB는 분말 / 액체로 만들어져 있으며, 브러시의 액량을 조절하여 유동성을 조절할 수 있습니다. TBB라고하는 강력한 촉매 덕분에 물과 산소가있는 상태에서도 중합이 가능하다는 장점이 있습니다. 또한 4-META를 함유하고있어 적절한 표면 처리로 금속 및 세라믹에 접착 할 수있는 장점이 있습니다. 이러한 장점을 충분히 이해하시면 기존의 복합 레진으로 처리하기 어려운 경우에 적극 활용할 수 있습니다. Bond-Fill SB is made of powder/liquid, and the flowability can be controlled by adjusting the amount of liquid in the brush. Thanks to the strong catalyst called TBB, it has the advantage of being able to polymerize even in the presence of water and oxygen. Also, since it contains 4-META, it has the advantage of being able to adhere to metals and ceramics with appropriate surface treatment. If you fully understand these advantages, you can actively utilize them in cases where it is difficult to treat with conventional composite resin.
김우현,채우규,황성욱,김주용,Kim, WooHyun,Chae, WooKyu,Hwang, SungWook,Kim, JuYong 한국전력공사 2022 KEPCO Journal on electric power and energy Vol.8 No.1
The radial distribution systems (RDS) commonly used around the world has the following disadvantages. First, when the DL is operated on a radial system, the line utilization rate is usually kept low. Second, if a fault occurs in the radial DL, a power outage of 3 to 5 minutes is occurring depending on the operator's proficiency and fault situation until the fault section is separated and the normal section is replaced. To solve this problem, Various methods have been proposed at domestic and foreign to solve this problem, and in Korea, research is underway on the advanced system of operating multiple linked DL always. A system that is electrically linked always, and that is built to enable high-speed communication during the protection coordination is named networked distribution system (NDS). Because the load shares the DL, the line utilization rate can be improved, and even if the line faults, the normal section does not need to be cut off, so the normal section does not experience a power outage. However, since it is impossible to predict in which direction the fault current will flow when a failure occurs in the NDS, a communication-based protection coordination is used, but there is no backup protection coordination method in case of communication failure. Therefore, in this paper, we propose a protective cooperation method to apply as a backup method when communication fails in NDS. The new method is to change TCC by location of CB using voltage drop in case of fault.
Electrical Characteristic Changes of ZnO Varistors by Energy Absorption
김우현,황성철,Guoming Wang,길경석,안창환 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.12
As a ZnO varistor is subjected to electrical and environmental stresses, it degrades gradually, which may resultin power interruption by short circuit. This study investigates changes in the electrical characteristics of ZnO varistorsdue to deterioration owing to energy absorption, and determines the optimal parameters for on-line diagnosis of thevaristor. Two types of varistors were used for an accelerated aging experiment involving the application of the 8/20 μsstandard lightning impulse current. The electrical characteristics in terms of the reference voltage, total leakage current,resistive leakage current, and third-harmonic component of the total leakage current were measured, and their changerates were analyzed. The results revealed that the total leakage current increased slightly with an increase in the varistorabsorbed energy, while the resistive leakage current and the third-harmonic component increased apparently. Therefore,the third-harmonic component of the total leakage current was proposed as the optimal parameter for on-line monitoringof ZnO varistor conditions.