0.6V 400㎻ 급 초저전력 델타-시그마 모듈레이터 설계

이현태(Hyuntae Lee),최영길(Youngkil Choi),노형동(Hyungdong Roh),노정진(Jeongjin Roh) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.11

In this paper, we propose a low-voltage, Jaw-power delta-sigma modulator for a implantable cardiac pacemaker. The distributed feed-forward structure and bulk-driven method are used for improved performance. The designed modulator achieves 53㏈ SNDR at 0.6v supply voltage and consumes 400㎻. The core chip size is 660㎛*500㎛ with 0.18㎛ CMOS standard process.

1-비트 4차 델타-시그마 변조기법을 이용한 D급 디지털 오디오 증폭기

강경식(Kyoungsik Kang),최영길(Youngkil Choi),노형동(Hyungdong Roh),남현석(Hyunseok Nam),노정진(Jeongjin Roh) 대한전자공학회 2008 電子工學會論文誌-SD (Semiconductor and devices) Vol.45 No.3

본 논문에서는 휴대용 오디오 제품의 헤드폰 구동을 위한 델타-시그마 변조기법 기반의 D급 증폭기를 제안한다. 제안된 D급 증폭기는 고성능 단일 비트 4차 델타-시그마 변조기를 이용하여 펄스폭 변조 신호를 발생 시킨다. 높은 신호 대 잡음비를 얻는 것과 동시에 시스템의 안정성 확보를 위하여 시뮬레이션을 통해 변조기 루프필터의 폴과 제로를 최적화 하였다. 테스트칩은 0.18㎛ CMOS 공정으로 제작 되었다. 칩 면적은 1.6㎟ 이며, 20㎐ 부터 20㎑까지의 신호대역을 대상으로 동작한다. 3V 전원전압과 32옴의 로드를 사용하여 측정된 출력은 0.03% 이하의 전고조파 왜율을 갖는다. In this paper, we present the design of delta-sigma modulation-based class-D amplifier for driving headphones in portable audio applications. The presented class-D amplifier generates PWM(pulse width modulation) signals using a single-bit fourth-order high-performance delta-sigma modulator. To achieve a high SNR(signal-to-noise ratio) and ensure system stability, the locations of the modulator loop filter poles and zeros are optimized and thoroughly simulated. The test chip is fabricated using a standard 0.18㎛ CMOS process. The active area of the chip is 1.6㎟. It operates for the signal bandwidth from 20㎐ to 20㎑. The measured THD+N(total harmonic distortion plus noise) at the 32Ω load terminal is less than 0.03% from a 3V power supply.

차량 가속 시 타이어 마찰 소음에 영향을 주는 타이어 설계 인자 기여도 분석

임종욱(JongWook Lim),고재현(JaeHyeon Ko),최영길(YoungKil Choi),나재봉(JaeBong Na),최우영(WooYoung Choi),장홍주(HongJu Jang),성기득(KiDeug Sung),김남균(NamGyun Kim) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11

The automobile market is changing from internal combustion engines to electric vehicles. Accordingly, the load of the vehicle increases due to the weight of the battery, and accelerates to a high torque at the time of departure. High torque and load affect the shear stress and grip interacting with the tyre block on the road surface. For this reason, in this study, tire friction noise emitted when a vehicle accelerates was studied. A method of obtaining the contribution of each tire structure factor contributing to tire friction noise using the Support Vector Regression was presented. The optimal specification result according to the noise result of the actual vehicle test and the contribution of the structural factor were compared and verified. In the future, noise reduction characteristics according to major factors will be studied, and actual vehicle test evaluation technology will be developed and used for electric vehicle acceleration noise research.

횡수막현상 시험방법에 관한 연구

송계주(Kyejoo Song),김현수(Hyunsoo Kim),이준은(Juneun Lee),최영길(Youngkil Choi),박병일(Byung-il Park) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11

Hydroplaning performance is one of the most important elements required for car safety under wet road conditions. This paper is a study of curved (lateral) hydroplaning, one of the two most common tyre testing methods alongside ‘straight (longitudinal)’ hydroplaning. While lateral acceleration has been typically used to evaluate the performance of hydroplaning in a curve, this paper shows a new method of evaluating hydroplaning in a curve. The new method projects cars on a wet road into the path of turning radius where hydroplaning is absent, and measures the length of arch projected. The new method proposed in this paper is expected to lead to a more efficient and accurate way of evaluating hydroplaning in a curve than currently exists.

우측 알도스테로노마의 복강경 부신절제술 1예

김준호,이상목,고석환,김경진,김영설,최영길 경희대학교 1997 慶熙醫學 Vol.13 No.2

성장호르몬분비성 뇌하수체 선종의 성장호르몬 방출호르몬 수용체 유전자의 발현과 내분비적 양상과의 관계

류미숙,양인명,박승준,우정택,김성운,김진우,김영설,최영길 경희대학교 생명자원과학연구원 1997 遺傳工學論文集 Vol.9 No.-

Growth hormone-releasing hormone (GHRH) plays a key role in the regulation of the proliferation and differentiation of somatomammotroph cells as well as secretion of GH. The actions of GHRH are mediated through the GHRH receptor (GHRH-R) that is a G protein coupled receptor with seven transmembrane domains. It has been demonstrated that alternative splicing occurs in the third cytoplasmic domain of rat and human GHRH-R mRNA. However, the clinical significance of the alternative splicing remains to be unsolved. To find an insight into the clinical significance, we investigate the correlation between the GHRH-R gene expression and a variety of clinical clinical and endocrinological findings in 11 acromegalic patients. Three different sized cDNA fragments 250 bp, 700 bp and 810 bp, were found after RT-PCR. The amount of 250 bp fragment was higher than those of the other two fragments. The clinical findings (age, size, GH level, frequency of paradoxical response to TRH or GnRH. octreotide response, hypothalamc somatostatinergic activity of the group with high expression of the 250 bp fragment did not significantly differ from those of the group with low expression. The GHRH-R gene expression of tumors with gsp oncogene did not significantly differ from that of tumors without gsp oncogene. These results suggest that the expression of GHRH-R gene may not be an important determinant for tumor growth, and the lower GH response to GHRH of tumors with gsp oncogene may not be attributed to the lower expression of GHRH-R gene. The expression of GHRH-R is likely to be regulated by a certain property of tumors for GH secretion and growth.

홍삼 복합제의 체지방 감소 작용 기전의 연구

신현대,박철영,팽정령,오승준,김영설,김성운,양인명,김진우,최영길 대한비만학회 2000 The Korean journal of obesity Vol.9 No.4

The effects of red ginseng compound preparation in weight loss have been confirmed, though its specific mechanism is unclear. The changes in both clinicai and lab results show body fat reduction through increase in energy metabolism after the administration. Therefore the effects of red ginseng compound preparation are likely to be caused by activation of sympathetic nervous system by beta-adrenalin system. The experiment was done in order to confirm this hypothesis on cellular level by administrating red ginseng compound preparation and extracting peripheral WBC to analyze adrenalin activation and its receptor RNA. Calorie-restricted diet and red ginseng compound preparation were given to 20 obese patients (BMI $gt; 27 kg/㎡) and 10 controls for duration of 4 weeks. (male to female ratio was 5:15) Changes in weight were from 80.5±15.3 kg (base line) to 79.2±14.7 kg (after taking red ginseng compound preparation) in the patient group, but in the control group did not decrease significantly. In similar sense, Bdecreased from 30.9±4.5 kg/㎡ (base line) to 30.4±4.3 kg/㎡ (after taking red ginseng compound preparation) in the patient group. However, BMI was not decreased in control group. Waist hip ratio was unchanged in both groups. The percent body fat was 35.16% (base line), 33.87% (after dieting), and 31.68% (after taking red ginseng compound preparation). Plasma epinephrine was increased in the patient group from 0.15±0.08ng/mL to 0.21±0.07 ng/mL, but in the contral group, the epinephrine level was decreased from 0.17±0.07 ng/mL to 0.14±0.05 ng/mL. The plasma norepinephrine levels of both groups showed no particular difference. To observe the possibility of 3 receptor expression, RT-PCR was done before and after drug administration. The results showed significant increase in receptor expression in both groups, in patient group increased from 0.87±0.45 to 1.79±0.78, and also increased in the control group from 0.62±0.33 to 0.91±0.53. The increase is quite significant in the patient group. The cAMP prod reflects the activity of beta-adrenaline was 10.1±6.1 S.I in patient group and 7.1±3.9 S.I in the control before drug administration. After administration, these changed to 12.3±6.1 S.I in the patient group and 4.8±1.4 S.I in the control group. Although this seems to show some increase in the patient group, it had no significant meaning statistically. The results shown above showed that the effects of red ginseng compound preparation in weight loss seem to result from increase in beta adrenaline activity, though this has not much meaning statistically. In particular, when we look at the increase of beta 3 adrenaline receptors in patient group, it can be that the effect of red ginseng compound preparation is lipolysis through the beta 3 receptor.