Limitation of High Pitch Sound Perception in Nontumor Patients with Auditory Brainstem Implantation

최현승,최재영,문인석,배미란,김보경,김민범,장진우,정준희 대한이비인후과학회 2018 대한이비인후과학회지 두경부외과학 Vol.61 No.5

Background and Objectives Auditory brainstem implantation (ABI) is another option forhearing rehabilitation in non-neurofibromatosis type 2 patients who cannot undergo cochlearimplantation (CI). However, the average performance of ABI is worse than that of CI. We analyzedthe psycho-electrical parameters of each electrode and psycho-acoustic response to differentfrequency sounds in nontumor patients with ABI. Subjects and Method Sixteen patients with ABI from July 2008 to May 2013 were includedin the study. They were followed up for 4 to 56 months. Among them, 12 were prelingualdeaf with a narrow internal auditory canal or cochlear ossification. The remaining four were postlingualdeaf adults with severely ossified cochleae. We analyzed the electrical parameters [impedance,threshold level (T level), and dynamic range] of each of the 12 electrodes. We alsoevaluated the sound field pure-tone threshold, Ling 6 sound detection-identification test (Ling6 test), and pitch ranking data of these patients. Results The impedance, T level, and dynamic range did not significantly differ among electrodes. However, the pure-tone threshold to sound field stimulation was elevated in the hightone area, where more variables were found than in the low frequency area. Patients could notidentify /S/ and /Sh/ sounds in the Ling 6 test. The mean T level and the dynamic range of thethree highest pitch-perceiving electrodes in each patient was higher and narrower, respectively,than those of the three lowest pitch-perceiving electrodes. Conclusion The nontumor patients with ABI have difficulty perceiving high pitch sound. More sophisticated penetrating type electrodes and, if possible, bimodal stimulation with CI,could be considered.

오토인코더 기반 네트워크 이상탐지

최현승,김민태,이규복,김우주 한국지능정보시스템학회 2018 한국지능정보시스템학회 학술대회논문집 Vol.2018 No.6

지식베이스 확장을 위한 멀티소스 비정형 문서에서의 정보 추출 시스템의 개발

최현승,김민태,김우주,신동욱,이용훈 한국지능정보시스템학회 2018 한국지능정보시스템학회 학술대회논문집 Vol.2018 No.11

초음파 분산에 의한 수직자기기록용 Ba-ferrite의 자기적 특성 향상

최현승,김창곤,장학진,정지형,윤석영,김태옥,Choi, Hyun-Seung,Kim, Chang-Gon,Jang, Hak-Jin,Jung, Ji-Hyung,Yoon, Seog-Young,Kim, Tae-Ok 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.8

The various ultrasonic energies (28 kHz, 40 kHz, 70 kHz) were used to improve the magnetic properties of Ba-ferrite as the perpendicular magnetic recording materials. In the sheet formation process, the different orientation hars were used to orientate perpendicularly the dispersed Ba-ferrite to sheet. Throughout these experiments, we have obtained relatively higher value of S. Q. (Squreness Ratio : 0.783) and O. R. (Orientation Ratio : 2.87) magnetic properties at 2 h ultrasonic treatment of 40 kHz ultrasonic energy. With aid of SEM(Scanning Electron Microscopy) images, the obtained sheet with dispersed of Ba-ferrite could be used for perpendicular magnetic recording due to orientated to easy magnetization axis, c-axis. In addition, the value of S. Q. of sheet decreased with increasing applied magnetic field angle during measuring of S. Q. value with changing applied magnetic field angle by VSM (Vibrating Sample Magnetrometer). This result also induced the probability for prependicular magnetic recording. 초음파 에너지(28 kHz, 40 kHz, 70 kHz)를 사용하여 수직자기기록용 Ba-ferrite의 자기적 특성 향상에 대하여 조사하였다. 한편, 분산된 Ba-ferrite를 sheet에 수직으로 배향시키기 위해 다양한 형태의 배향기들을 사용하여 실험을 행하였다. Ba-ferrite가 도포된 sheet 중 초음파 에너지가 40 kHz이고 초음파 처리 시간이 2시간에서 자기적 특성인 S. Q. (Squareness Ratio)와 O. R. (Orientation Ratio)값이 각각 0.7831과 2.87로 비교적 좋은 값을 얻을 수 있었다. 이때 얻어진 sheet의 표면 형상을 SEM(Scanning Electron Microscopy)으로 분석한 결과 Ba-ferrite가 자화용이축인 c 축에 수직방향으로 배향되어 수직자기기록용으로서의 응용에 가능성을 보였다. 또한, VSM(Vibrating Sample Magnetometer)으로 자기장의 각도변화에 따른 S. Q.의 측정시, 자기장의 각도가 증가함에 따라 S. Q. 값이 감소하였고 이는 수직자기기록용으로써 가능성을 재확인 시켜주었다.

지식베이스 확장을 위한멀티소스 비정형 문서에서의 정보 추출 시스템의 개발

최현승,김민태,김우주,신동욱,이용훈 한국지능정보시스템학회 2018 지능정보연구 Vol.24 No.4

In this paper, we propose a methodology to extract answer information about queries from various types of unstructured documents collected from multi-sources existing on web in order to expand knowledge base. The proposed methodology is divided into the following steps. 1) Collect relevant documents from Wikipedia, Naver encyclopedia, and Naver news sources for “subject-predicate“ separated queries and classify the proper documents. 2) Determine whether the sentence is suitable for extracting information and derive the confidence. 3) Based on the predicate feature, extract the information in the proper sentence and derive the overall confidence of the information extraction result. In order to evaluate the performance of the information extraction system, we selected 400 queries from the artificial intelligence speaker of SK-Telecom. Compared with the baseline model, it is confirmed that it shows higher performance index than the existing model. The contribution of this study is that we develop a sequence tagging model based on bi-directional LSTM-CRF using the predicate feature of the query, with this we developed a robust model that can maintain high recall performance even in various types of unstructured documents collected from multiple sources. The problem of information extraction for knowledge base extension should take into account heterogeneous characteristics of source-specific document types. The proposed methodology proved to extract information effectively from various types of unstructured documents compared to the baseline model. There is a limitation in previous research that the performance is poor when extracting information about the document type that is different from the training data. In addition, this study can prevent unnecessary information extraction attempts from the documents that do not include the answer information through the process for predicting the suitability of information extraction of documents and sentences before the information extraction step. It is meaningful that we provided a method that precision performance can be maintained even in actual web environment. The information extraction problem for the knowledge base expansion has the characteristic that it can not guarantee whether the document includes the correct answer because it is aimed at the unstructured document existing in the real web. When the question answering is performed on a real web, previous machine reading comprehension studies has a limitation that it shows a low level of precision because it frequently attempts to extract an answer even in a document in which there is no correct answer. The policy that predicts the suitability of document and sentence information extraction is meaningful in that it contributes to maintaining the performance of information extraction even in real web environment. The limitations of this study and future research directions are as follows. First, it is a problem related to data preprocessing. In this study, the unit of knowledge extraction is classified through the morphological analysis based on the open source Konlpy python package, and the information extraction result can be improperly performed because morphological analysis is not performed properly. To enhance the performance of information extraction results, it is necessary to develop an advanced morpheme analyzer. Second, it is a problem of entity ambiguity. The information extraction system of this study can not distinguish the same name that has different intention. If several people with the same name appear in the news, the system may not extract information about the intended query. In future research, it is necessary to take measures to identify the person with the same name. Third, it is a problem of evaluation query data. In this study, we selected 400 of user queries collected from SK Telecom 's interactive artificial intelligent speaker to evaluate the performance of the information extraction ... 지식베이스를 구축하는 작업은 도메인 전문가가 온톨로지 스키마를 이해한 뒤, 직접 지식을 정제하는 수작업이 요구되는 만큼 비용이 많이 드는 활동이다. 이에, 도메인 전문가 없이 다양한 웹 환경으로부터 질의에 대한 답변 정보를 추출하기 위한 자동화된 시스템의 연구개발의 필요성이 제기되고 있다. 기존의 정보 추출 관련연구들은 웹에 존재하는 다양한 형태의 문서 중 학습데이터와 상이한 형태의 문서에서는 정보를 효과적으로 추출하기 어렵다는 한계점이 존재한다. 또한, 기계 독해와 관련된 연구들은 문서에 정답이 있는 경우를 가정하고질의에 대한 답변정보를 추출하는 경우로서, 문서의 정답포함 여부를 보장할 수 없는 실제 웹의 비정형 문서로부터의 정보추출에서는 낮은 성능을 보인다는 한계점이 존재한다. 본 연구에서는 지식베이스 확장을 위하여 웹에 존재하는 멀티소스 비정형 문서로부터 질의에 대한 정보를 추출하기 위한 시스템의 개발 방법론을 제안하고자 한다. 본 연구에서 제안한 방법론은 “주어(Subject)-서술어(Predicate)”로 구분된 질의에 대하여 위키피디아, 네이버 백과사전, 네이버 뉴스 3개 웹 소스로부터 수집된 비정형 문서로부터 관련 정보를 추출하며, 제안된 방법론을 적용한 시스템의 성능평가를 위하여, Wu and Weld(2007)의 모델을 베이스라인 모델로 선정하여 성능을비교분석 하였다. 연구결과 제안된 모델이 베이스라인 모델에 비해, 위키피디아, 네이버 백과사전, 네이버 뉴스등 다양한 형태의 문서에서 정보를 효과적으로 추출하는 강건한 모델임을 입증하였다. 본 연구의 결과는 현업지식베이스 관리자에게 지식베이스 확장을 위한 웹에서 질의에 대한 답변정보를 추출하기 위한 시스템 개발의지침서로서 실무적인 시사점을 제공함과 동시에, 추후 다양한 형태의 질의응답 시스템 및 정보추출 연구로의확장에 기여할 수 있을 것으로 기대한다.

AFM용 자기부상 스테이지를 위한 Halbach Magnet Array 특성해석

최현승,염우섭,박기환 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.5월

졸-겔 합성에 의한 BaFe_12-2xCo_xTi_xO₁₉ 미립자의 자기적 특성

최현승,정지형,박효열,김태옥 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.1

졸-겔법으로 보자력 제어에 뛰어난 첨가제인 Co와 Ti을 첨가한 Ba-ferrite 미립자를 합성하였다. 졸-겔 반응시, 반응 시간이 90분에서 120분 이내에서 온도, pH 및 점도의 변화가 없고, aging 시간에 따라 점도가 안정한 상태치 졸을 얻을 수 있었다. 이 졸을 건조 및 열처리 후, Differential Thermal Analysis(DTA)와 X-Ray Diffractometer(XRD)를 통해 Ba-ferrite 상이 약 $700^{\circ}C$부터 생성됨을 확인하였으며, 열처리 온도 증가에 의해 결정성이 좋아짐을 볼 수 있었다. Scanning Election Microscopy(SEM)로 표면형상을 관찰한 결과 열처리 온도가 증가함에 따라 입자크기가 증가하였으며, 비교적 균질한 입도 분포의 미립자를 얻을 수 있었다. 또한, Vibrating Sample Magnetometer(VSM)로 Co와 Ti의 첨가량에 따른 자기적 특성을 관찰하였으며, 포화자화(M$_{s}$ )값은 첨가량에 관계없이 변화가 없었으나, 보자력(H$_{c}$)값은 첨가량에 따라 크게 변화하였다. Ba-ferrite particles added with Co and Ti, which were known well the additives for the control in coercivity, were synthesized by sol-gel method. In the range 90 to 120 minute reaction time, a stable sol solution which showed no change with temperature, pH, viscosity and aging time. After dried and heat treatment of sol solution, Ba-ferrite phase formed at $700^{\circ}C$ with Differential Thermal Analysis(DTA) and X-Ray Diffractometer(XRD) measurement. The crystallinity became to be better with increasing the temperature. It were showed by Scanning Electron Microscopy(SEM) that Ba-ferrite increased to particle sizes as increasing heating temperature and obtained of narrow particles size distribution. Also, magnetic characteristics of Ba-ferrite powders Co and Ti added were observed by a Vibrating Sample Magnetometer(VSM). Saturation magnetization$(M_s)$ was not much changed, however. the coercivity$(H_c)$dramatically dropped with addition of Co and Ti.

의료원가분석을 통한 편도 및 아데노이드 절제술의 경제적 적정성 연구

최현승,정세원,김창용,장정현 대한이비인후과학회 2015 대한이비인후과학회지 두경부외과학 Vol.58 No.9

Background and Objectives The Korean National Health Insurance is based on ‘fee for service’ system, but recently 7 groups of diseases were forcibly applied to diagnosis related groups (DRG) system. In these 7 group of diseases, tonsillectomy and adenoidectomy were included in the otorhinolaryngology field. The objective of this research is to estimate the invested medical costs, profit and loss, and improvement points for the disease groups according to DRG and ‘fee for service’ system. Subjects and Method We investigated 1,377 subjects who underwent tonsillectomy and adenoidectomy based on DRG between January 2011 to December 2013 at our hospital. The profit and loss of medical costs were calculated according to medical record data, medical service fee, and activity based costing (ABC). Results The total of 1,377 subject comprised of 905 patients younger than 17 years-old and 472 patients older than 18 years-old. A main moderate complication that was not one of the DRG diseases, postoperative bleeding, was only found in 19 patients (1.38%). Profit related to tonsillectomy and adenoidectomy studied for a 3 year-period was higher in the DRG system than in the ‘fee for service’ system; however, profit was reported as 62.9-67.5% of the actual prime costs. Conclusion DRG system for tonsillectomy and adenoidectomy seems to have higher compensation rate than the ‘fee for service’ system does. However, the system is still insufficient to compare profit with the input medical cost. Furthermore, the present system of disease grouping needs to be improved to reflect actual medical prime costs.

졸-겔법에 의한 Cobalt 치환된 Ba-ferrite 분말의 자기적 특성

최현승,박효열,윤석영,신학기,김태옥,Choi, Hyun-Seung,Park, Hyo-Yul,Yoon, Seog-Young,Shin, Hak-Gi,Kim, Tae-Ok 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.8

본 연구에서는 TMS[Tetramethylsilane:$Si(CH_3)_4$], $NH_3$와 $H2$를 이용하여 나노크기의 Si-C-N precursor 분말을 합성하기 위하여 CVC법을 이용하였으며 반응온도, TMS/$NH_3$ 비 그리고 TMS/$H_2$ 비를 변화시켰다. XRD와 FESEM 분석을 통해서 결정상과 입자의 크기 그리고 입자의 형태를 관찰하고자 하였으며, 그 결과 제조된 분말은 모든 실험 조건하에서 87∼130 nm 크기를 지닌 균일한 구형의 비정질 분말이 얻어졌다. 입자 크기는 반응온도의 감소에 따라 감소하였으며, 또한 TMS/$NH_3$, TMS/$H_2$ 비가 작아질수록 감소하였다. EA 분석 결과 제조된 분말은 Si, N, C, H로 이루어졌음을 알 수 있었으며 FT-IR를 통하여 Si-N, C-N, Si-C 결합을 가진 Si-C-N precursor 분말이 제조되었다. In this study, nano-sized Si-C-N precursor powders were synthesized by Chemical Vapor Condensation Method(CVC) using TMS(Tetramethylsilane: $Si(CH_3)_4$), $NH_3$ and $H_2$ gases under the various reaction conditions of the reaction temperature, TMS/$NH_3$ ratio and TMS/$H_2$ ratio. XRD and FESEM were used to analysis the crystalline phase and the average particle size of the synthesized powders. It was found that the obtained powders under the considering conditions were all spherical amorphous powder with the particle size of 87∼130 nm. The particle size was decreased as the reaction temperature increased and TMS/$NH_3$ and TMS/$H_2$ ratio decreased. As the results of EA analysis, it was found that the synthesized powders had been formed the powders composed of Si, N, C and H. Through FT-IR results, it was found that the synthesized powders were Si-C-N precursor powders with Si-C, Si-N and C-N bonds.

듀얼 위상 주파수 검출기를 이용한 CMOS RF Charge-Pump PLL 설계

최현승,김종민,박창선,이준호,이근호,김동용 한국통신학회 2001 韓國通信學會論文誌 Vol.26 No.10

본 논문에서는 위상획득과정과 동기과정에서 trade-off 현상을 향상시킨 듀얼 위상 주파수 검출기를 제안하여 차지펌프 PLL을 설계하였다. 듀얼 위상 주파수 검출기는 상승에지에서 동작하는 POSITIVE 위상 주파수 검출기와 하강에지에서 동작하는 NEGATIVE 위상 주파수 검출기로 구성되어 있다. 제안한 차지펌프는 전류뺄셈회로를 이용하여 전류 부정합을 감소시켰으며, reference spurs와 전압제어발진기의 변동을 감소시킬 수 있도록 구현하였다. 제안한 차지펌프 PLL은 0.25$\mu\textrm{m}$ CMOS 공정을 사용하여 SPICE로 시뮬레이션 하였으며, 그 결과 1.6~1.85GHz의 넓은 동기범위를 나타내었다.