GDDR3 Memory Controller용 Impedance Calibration과 Level Shifter를 이용한 I/O Buffer 설계

김현창(Hyun-Chang Kim),황문상(Moon-Sang Hwang),김성우(Sung-Woo Kim),김태호(Tae Ho Kim),정덕균(Deog-Kyoon Jeong) 대한전자공학회 2010 대한전자공학회 학술대회 Vol.2010 No.6

An I/O buffer with impedance calibration feature for GDDR3 memory controller is presented in this paper. The proposed I/O buffer operates upto 1.2 Gb/s with 1.8-V supply voltage. The test chip was fabricated in standard 0.13-㎛CMOS process with 1.2-V supply voltage. A level-up shifter and a level-down shifter with little duty-cycle distortion are also introduced to implement 1.8-V I/O buffers in given process.

새로운 ERM-방법에 의한 미세구조 N-채널 MOSFET의 유효 캐리어 이동도와 소스 및 드레인 기생저항의 정확한 분리 추출

金炫昌(Hyun Chang Kim),曺洙東(Su Dong Cho),宋尙駿(Sang Jun Song),金大井(Dea Jeong Kim),金東明(Dong Myong Kim) 大韓電子工學會 2000 電子工學會論文誌-SD (Semiconductor and devices) Vol.37 No.12

미세구조 N-채널 MOSFET의 게이트-소스 전압에 의존하는 유효 채널 캐리어 이동도와 소스 및 드레인 기생저항의 정확한 분리 추출을 위해서 새로운 ERM 방법을 제안하였다. ERM-방법은 선형영역에서 동작하는 게이트 길이가 다른 두개의 소자(W<SUB>m</SUB>/L<SUB>m</SUB>=30㎛/0.6㎛, 30㎛/1㎛)에 적용되었고 유효 채널 캐리어 이동도를 모델링하고 추출하는 과정에서 게이트-소스 전압에 의존하는 소스 및 드레인 기생저항의 영향 을 고려하였다. ERM-방법으로 추출된 특성변수들을 사용한 해석적 모델식과 소자의 측정데이터를 비교해본 결과 오차가 거의 없이 일치하는 것을 확인하였다. 따라서 ERM-방법을 사용하면 대칭구조 및 비대칭구조 소자의 유효 채널 캐리어 이옹도, 소스 및 드레인 기생저항과 다른 특성변수들을 정확하고 효율적으로 추출 할 수 있을 것으로 기대된다. A new method, the external resistance method (ERM method), is proposed for accurate extraction of the gate bias-dependent effective channel carrier mobility (μ<SUB>eff</SUB>) and separated parasitic source/drain resistances (R<SUB>S</SUB> andR<SUB>D</SUB>) of n-channel MOSFET’s. The proposed ERM method is applied to n-channel LDD MOSFETs with two different gate lengths (W<SUB>m</SUB>/L<SUB>m</SUB>=30 ㎛/0.6 ㎛, 30 ㎛/1 ㎛) in the linear mode of current-voltage characteristics (I<SUB>D</SUB>-V<SUB>GS</SUB>, V<SUB>DS</SUB>). We also considered gate voltage dependence of separated R<SUB>S</SUB> and R<SUB>D</SUB> in the accurate modeling and extraction of effective channel carrier mobility. Good agreement of experimental data is observed in submicron n-channel LDD MOSFETs. Combining with capacitance-voltage characteristics, the ERM method is expected to be very useful for accurate and efficient extraction of μ<SUB>eff</SUB>, R<SUB>D</SUB>, R<SUB>S</SUB>, and other characteristic parameters in both symmetric and asymmetric structure MOSFET’s in which parasitic resistances are critical to the improvement of high speed performance and reliability.

A Flicker-Free LED Driver with Stacked Buck-Boost Topology for Lighting Applications

김현창(Hyun-Chang Kim),정덕균(Deog-Kyoon Jeong) 대한전자공학회 2015 대한전자공학회 학술대회 Vol.2015 No.6

우나무노(Miguel de Unamuno)의 철학(哲學)과 생(生)의 비극적(悲劇的) 감정(感情)

김현창 ( Hyun Chang Kim ) 서울대학교 인문학연구원 1989 人文論叢 Vol.22 No.-

Unamuno is at once a great author and a philosopher Spain produced at the beginning of the 20th century. Unamuno has a very original personality, knowing how to harmonize literature and philosophy. He is also a paradoxical and anti-rational writer, and the theme he treats repeatedly in his writings coincides with the essential philosophical subject. In this sense we can say he is a philosophical author. His works are, however, remarkable literary ones by their own quality. They are nevertheless no simple literarily decoration to the philosphical thinking. Unamuno is much too artistically and literary well-grounded to walk into that trap. When Unamuno writes, he tries to show us something more; for example he is haunted by the problem of human conscience after death. At the same time, his meditation centes on the man of flesh and bones, not on the abstract humanity. Reason is an enemy of life for Unamuno. For this he refuses to express his philosophy through reason. Arriving at the conclusion that reason can`t solve the problems of life and death, Unamuno chooses novel and drama, in other words, literature, as a means to express his philosophy. Inconvenience, life`s difficulties are the causes of anguish, and anguish appears when one can`t adapt oneself to the conditions of life. However it is through anguish we can arrive at truth and immortality. The tragical sentiment of life of Unamuno manifests itself when the author comes to realize that life and death depend on the Creator and not on himself. This doctrine has been made clear in "Niebla". This novel represents very well the philosophy of Unamuno`s tragical sentiment of life. According to Unamuno, religion presupposes the existence of man, not of God. The human desire to have the immortality of the soul makes man create religion. Unamuno refuses pure and unconditional faith. Eternal ignorance is not acceptable for Unamuno. You have to fight until death to conquer the mystery of life. This problem of faith is well expressed in "San Manuel bueno, martir." Unamuno has meditated much on death. His meditation is especially concentrated on the immortality of the soul. For Unamuno two means exist to conquer death: the first is immortality and the second resurrection. As far as his existentialism is concerned, he has been deeply influenced by Kierkegaard and Spinoza. Unamuno has realized his literature through philosophy and his philosophy through literature. Completing this monumental work he has shown us the new horizon literature and philosophy can have.

역경문화 : 서구에 주역철학이 수용,전개된 양상에 관한 논구

김현창 ( Hyun Chang Kim ) 한국역경문화학회 2004 주역철학과 문화 Vol.2 No.-

CCD카메라를 이용한 생물감시장치의 독성자료 신뢰성 향상에 관한 연구

김현창(Hyun Chang Kim),김영석(Young Suk Kim) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.10

우리나라 주요하천의 수질오염감시를 목적으로 물벼룩을 이용한 생물감시장치가 설치, 운용되고 있다. 기기 목적상 유해물질에 대해 신뢰성 있는 신속한 독성경보를 내릴 수 있어야 하고, 무인원격측정기기이므로 계절별, 연간 하천의 물리적인 변화에도 측정의 신뢰성이 확보되어야 한다. 국내에 운영중인 장비는 물벼룩의 단위시간당 뛰는 횟수(Impulse)를 측정하는 방법과 유영형태를 분석하여 독성지수(Toxicity)로 나타내는 방법이 있다. 두 장비가 동일한 조건에서 운전되었음에도 가동률과 긴급점검횟수가 다르게 나타났으며 원인은 용기 내 기포발생과 압력차이 등 여러 가지가 있다. 본 연구의 목적은 기포와 미시적인 압력의 영향을 감소시켜 측정의 불확실성을 줄이는 것이고, 나아가 생물감시장치가 어떤 환경에 설치되더라도 수질오염감시의 목적을 정상적으로 달성하는 데 기여하는 것이다. Water monitoring equipments using daphnia can be used to monitor the pollution levels of a country's main rivers. Such equipments should be capable of providing a prompt warning about increase in the contamination levels, which is evaluated on the basis of impulse number or toxicity index. As unmanned remote control equipments, they must provide reliable pollution monitoring results for each season and for the annual physical changes in each river. Two different equipments based on the impulse number and toxicity index showed different results for the operating rates and for the number of emergency checks required even though both were operated at the same conditions. The results are affected by many parameters such as the presence of any air bubbles and the microscopic pressure. The purpose of this study is to develop a method that can reduce the effect of bubbles or microscopic pressure on the monitoring data. We expect to achieve reliable monitoring data for water pollutants irrespective of the location of the equipment setup.

가르시아 로르까(GARCIA LORCA)의 시(詩)와 희곡(戱曲)에 나타난 죽음

김현창 ( Hyun Chang Kim ) 서울대학교 인문학연구원 1988 人文論叢 Vol.20 No.-

This thesis treats essentially with death, expressed in the poetry and plays of Garcia Lorca. To understand his poetry, one must pay attention to the poetic theory of "duende" of which Lorca says he is possessed. The conception of "duende" of Garcia Lorca corresponds to a certain form of fatalism and indigenous belief of Andalucia. Garcia Lorca has also prepared a festival of cante jondo in collaboration with Manual de Falla. When Lorca speaks of "duende," it is very human, and differs from "Musa" or "angel.`` This means that "duende" is a presupposition of death as a human being. From his first volume of verse "Libro de poemas" on, he mentions and chants death, but the works in which he starts speaking intensively of death are: "Cante jondo" and "Romancero gitano." In "Cante jondo" he treats of death as if he admires it. "Romancero gitano" is about the tragic destiny of the gipsies. Here we can find words as: knife, dagger, battle, death and persecution, especially persecution of the gipsies by the guardia civil (police). In "Llanto por Ignacio Sanchez Mejias," we can not only read about the blood and the inevitable death of the toreros (bull-fighters), but also about the victory of death by their courage and valour, and the nobility of their attitude. In the three poems of which "Llanto por Ignacio Sanchez Mejias" consists, death is not an abominable thing, but it is charming, warm, and embraces the human being as an affectionate mother does with her children. In these poems we can easily appreciate the estetics of death as seen by Garcia Lorca. Here death is conquered and transformed in immortality by the valour of a real man. In the poems "Poeta en Nueva York," Lorca pays attention to the negros, just as he did with the gipsies of Spain in his previous poetry. This poetry is the culmination of Lorca``s esoterism. He chants the tragic destiny of the negros, their poverty, misery, disdain of the white people and death. In one of the poems of this volume of verse: "Jntroduccion a la muerte" (Introduction to Death), we can easily observe his obsession of death and death among the negros. Among several plays, three tragedies are representative: "Boda de sangre," "Yerma" and "La casa de Bernarda Alba." In each of the plays, the protagonists have a tragic death, In the Greek tragedies, death results of external factors, but in Lorca`s tra g edies internal factors are the reason of death. To conclude we can say that Garcia Lorca chants death from the beginning of his poetical creation on, till his last work, in an intensive way. Death as Lorca sees it is not a definite death, but it is a part of his life. In one thousand years of Spanish liter-□uture, we can rarely find a poet who mentions death as intensively as Garcia Lorca did.

수질관리 : CCD 카메라를 이용한 생물감시장치의 기포발생과 압력변화가 독성평가에 미치는 영향분석

김현창 ( Hyun Chang Kim ),고재윤 ( Jae Yun Ko ),송재덕 ( Jae Deok Song ),김대승 ( Dae Sung Kim ),김인탁 ( Ihn Tak Kim ) 한국물환경학회 ( 구 한국수질보전학회 ) 2009 공동 추계학술발표회 Vol.2009 No.-

체질량지수와 유방암발생의 관련성

임선미 ( Sun Mi Lim ),허남욱 ( Nam Wook Hur ),김현창 ( Hyun Chang Kim ),강대용 ( Dae Ryong Kang ),서일 ( Il Suh ) 한국보건정보통계학회 (구 한국보건통계학회) 2011 보건정보통계학회지 Vol.36 No.1

Objectives: This study investigated the association between body mass index (BMI) (and its change) and risk of breast cancer in Korea women by age. Methods: Participants were 64,149 women aged 35~59 years at the baseline (1990~1992) of the Korea Medical Insurance Corporation study. They were stratified as 44,923 women aged 37~47 years and 19,226 women aged 48~61 years by age at year 1992. BMI change was defined as BMI at 1994 minus baseline BMI. Baseline BMI was categorized quartile and first quartile used as reference group for the analysis. BMI change was categorized quartile and second quartile used as reference group for the analysis. Hazard ratio (HR) calculated using Cox`s proportional hazard model. Results: Baseline BMI and breast cancer risk were not associated in women aged < 48 (HR = 0.83, p for trend = 0.182 for Q4 vs Q1), but associated in women aged ≥ 48 (HR = 2.08, p for trend = 0.002 for Q4 vs Q1). However, BMI change was not associated with breast cancer risk in either age group. Conclusions: These results suggest that obesity may be a risk factor breast cancer in premenopausal women but not in post menopausal women.

처방선량 및 치료기법별 치료성적 분석 결과에 기반한 자궁경부암 환자의 최적 방사선치료 스케쥴

조재호(Jae Ho Cho),김현창(Hyun Chang Kim),서창옥(Chang Ok Suh),이창걸(Chang Geol Lee),금기창(Ki Chang Keum),조남훈(Nam Hoon Cho),이익재(Ik Jae Lee),심수정(Su Jung Shim),서양권(Yang Kwon Suh),성진실(Jinsil Seong),김귀언(Gwi Eon Kim) 대한방사선종양학회 2005 Radiation Oncology Journal Vol.23 No.3

목 적: 고선량률 강내근접치료와 외부방사선의 병합치료는 자궁경부암의 표준치료법이지만, 최적의 병합 방식 및 선량 분할 스케쥴은 아직 정해지지 않고 있다. 부분적으로는 이에 영향을 미치는 인자들의 다양성 및 기존의 문헌 들의 방사선 선량에 관한 자세한 정보 부족을 그 이유로 들 수 있다. 이에 본 연구는 고선량률 강내근접치료에 대 한 풍부한 경험을 바탕으로 단일기관에서 비교적 균일한 치료를 받은 많은 수의 환자 모집단을 대상으로 이들 다 양한 인자들 및 방사선치료에 대한 자세한 분석을 통해서 최적의 방사선치료를 위한 지침을 얻고자 하였다. 대상 및 방법: 1990년부터 1996년까지 연세암센터에서 고선량률 강내근접치료 및 외부방사선치료로 자궁경부암 에 대한 근치적 치료를 받은 743명의 환자들을 대상으로 하였으며, 중앙추적관찰 기간은 52개월이었다. FIGO 병기 분포는 IB 198명, IIA 77명, IIB 364명, IIIA 7명, IIIB 89명, IVA 8명이었다. 전골반방사선 선량은 23.4∼59.4 Gy (중앙값 45 Gy)의 분포를 보였으며, 진단 시 종양의 크기 및 외부방사선치료에 대한 종양의 반응에 따라서 그 시기를 조절 하는 중앙차폐는 495예에서 시행되었으며, 그 시기는 14.4∼43.2 Gy (중앙값 36.0 Gy)로 비교적 광범위하고 다양한 분포를 보였다. 강내근접치료와 외부방사선치료의 분할 선량 차이를 극복하기 위해 생물학적 유효선량(Biologically Effective Dose, BED) 개념을 적용하였으며, 종양 및 정상 조직에 대한 α/β비는 각각 10 및 3으로 하였다. 모든 개 별 환자의 직장 전벽 및 방광 흡수선량을 분석하였고, 합병증 및 골반제어율과의 상관 관계를 규명하고자 하였다. 이외에도 방사선치료 스케쥴에 영향을 미칠 수 있는 인자들인 총 치료기간, 강내근접치료의 분할 선량 크기, 주치 의의 선호도에 따른 치료 스케쥴 차이 등도 함께 고려하여 분석하였다. 결 과: 전체 환자에서 RTOG Grade 1-4 독성 발생률은 33.1%였다. 전체 환자의 5년 골반제어율은 83%로 분석되었다. 중앙차폐이전 외부방사선선량과 강내근접치료의 합산 BED값(=MD-BED Gyα/β은 α/β=10인 경우 62.0∼121.9 Gy10 (중앙값= 93.0 Gy10)의 분포를, α/β=3인 경우 93.6∼187.3 Gy3 (중앙값=137.6 Gy3)의 분포를 보였다. MD-BED Gy3는 직장합병증 발생과의 관계는 통계적으로 유의하였고, 방광합병증과는 유의하지 않았다. 직장합병증과의 연관성은 MD-BED Gy3보다 개별 환자의 직장전벽 총 선량 BED값인 R-BED Gy3가 훨씬 더 높았다. 요도카테터 풍선의 후방지점이 대변하는 방광의 총 선량 BED값인 V-BED Gy3도 방광합병증과 경향성 테스트에서 통계적 유의성을 보였다. 하지만, 어떠한 방사선선량도 골반제어율과 의미 있는 상관관계를 보이지 않았다. 본 기관에서 주치의의 선호도에 따라 강내근접치료가 외부방사선치료의 중간에 시행되는 형태인 샌드위치기법과 외부방사선치료 후반부에 시행되는 순차적 기법으로 구분하였을 때, 두 방식간 치료성적 및 합병증의 차이는 없었다. 총 치료기간에 대한 분석에서는 치료기간이 길어질수록 재발 위험이 커지는 경향을 보였으나, 나이 및 병기, 종양의 크 기, MD-BED Gy10 등의 예후 인자를 보정한 다변량분석에서는 치료기간이 100일 이상인 경우에만 통계적으로 유의하게 증가하였다. 강내근접치료 분할선량 크기인 3 Gy와 5 Gy 사이에 골반제어율 및 합병증의 차이는 없었다.결 론: 자궁경부암의 최적방사선치료 스케쥴에 대한 지침을 세우기 어렵게 만드는 가장 중요한 이유는 강내근접치료가 갖는 선량분포 특성에서 기인하는 방사선선량-골반제어율 상관 관계의 부재 및 개별 종양의 방사선에 대한 반응 속도가 환자마다 크게 다를 수 있다는 점이다. 따라서 전체적인 원칙과 함께 개인화된 맞춤치료가 필요하다. 치료 지침에 영향을 미칠 수 있는 요소들의 복합적인 고려도 중요하다고 할 수 있겠다. 합병증 발생이 우려되는 경우 생물학적 유효선량을 낮추기 위해 적절한 조기 중앙차폐 및 강내근접치료의 분할선량 크기 감소를 고려해볼 수 있다. Background: The best dose-fractionation regimen of the definitive radiotherapy for cervix cancer remains to be clearly determined. It seems to be partially attributed to the complexity of the affecting factors and the lack of detailed information on external and intra-cavitary fractionation. To find optimal practice guidelines, our experiences of the combination of external beam radiotherapy (EBRT) and high-dose-rate intracavitary brachytherapy (HDR-ICBT) were reviewed with detailed information of the various treatment parameters obtained from a large cohort of women treated homogeneously at a single institute. Materials and Methods: The subjects were 743 cervical cancer patients (Stage IB 198, IIA 77, IIB 364, IIIA 7, IIIB 89 and IVA 8) treated by radiotherapy alone, between 1990 and 1996. A total external beam radiotherapy (EBRT) dose of 23.4∼59.4 Gy (Median 45.0) was delivered to the whole pelvis. High-dose-rate intracavitary brachytherapy (HDR-ICBT) was also performed using various fractionation schemes. A Midline block (MLB) was initiated after the delivery of 14.4∼43.2 Gy (Median 36.0) of EBRT in 495 patients, while in the other 248 patients EBRT could not be used due to slow tumor regression or the huge initial bulk of tumor. The point A, actual bladder & rectal doses were individually assessed in all patients. The biologically effective dose (BED) to the tumor (α/β=10) and late-responding tissues (α/β=3) for both EBRT and HDR-ICBT were calculated. The total BED values to point A, the actual bladder and rectal reference points were the summation of the EBRT and HDR-ICBT. In addition to all the details on dose-fractionation, the other factors (i.e. the overall treatment time, physicians preference) that can affect the schedule of the definitive radiotherapy were also thoroughly analyzed. The association between MD-BED Gy3 and the risk of complication was assessed using serial multiple logistic regression models. The associations between R-BED Gy3 and rectal complications and between V-BED Gy3 and bladder complications were assessed using multiple logistic regression models after adjustment for age, stage, tumor size and treatment duration. Serial Coxs proportional hazard regression models were used to estimate the relative risks of recurrence due to MD-BED Gy10, and the treatment duration. Results: The overall complication rate for RTOG Grades 1∼4 toxicities was 33.1%. The 5-year actuarial pelvic control rate for all 743 patients was 83%. The midline cumulative BED dose, which is the sum of external midline BED and HDR-ICBT point A BED, ranged from 62.0 to 121.9 Gy10 (median 93.0) for tumors and from 93.6 to 187.3 Gy3 (median 137.6) for late responding tissues. The median cumulative values of actual rectal (R-BED Gy3) and bladder point BED (V-BED Gy3) were 118.7 Gy3 (range 48.8∼265.2) and 126.1 Gy3 (range: 54.9∼267.5), respectively. MD-BED Gy3 showed a good correlation with rectal (p=0.003), but not with bladder complications (p=0.095). R-BED Gy3 had a very strong association (p=<0.0001), and was more predictive of rectal complications than A-BED Gy3. B-BED Gy3 also showed significance in the prediction of bladder complications in a trend test (p=0.0298). No statistically significant dose-response relationship for pelvic control was observed. The Sandwich and Continuous techniques, which differ according to when the ICR was inserted during the EBRT and due to the physicians preference, showed no differences in the local control and complication rates; there were also no differences in the 3 vs. 5 Gy fraction size of HDR-ICBT. Conclusion: The main reasons optimal dose-fractionation guidelines are not easily established is due to the absence of a dose-response relationship for tumor control as a result of the high-dose gradient of HDR-ICBT, individual differences in tumor responses to radiation therapy and the complexity of affecting factors.