3.0T MRI에서 온도변화가 T1 및 T2 이완시간에 미치는 영향

김호현,권순용,임우택,강충환,김경수,김순배,백문영,Kim, Ho-Hyun,Kwon, Soon-Yong,Lim, Woo-Teak,Kang, Chung-Hwan,Kim, Kyung-Soo,Kim, Soon-Bae,Baek, Moon-Young 대한디지털의료영상학회 2013 대한디지털의료영상학회논문지 Vol.15 No.2

Purpose : The relaxation times of tissue in MRI depend on strength of magnetic field, morphology of nuclear, viscosity, size of molecules and temperature. This study intended to analyze quantitatively that materials' temperatures have effects on T1 and T2 relaxation times without changing of other conditions. Materials and Methods : The equipment was used MAGNETOM SKYRA of 3.0T(SIEMENS, Erlagen, Germany), 32 channel spine coil and Gd-DTPA water concentration phantom. To find out T1 relaxation time, Inversion Recovery Spin Echo sequences were used at 50, 400, 1100, 2500 ms of TI. To find out T2 relaxation time, Multi Echo Spin Echo sequences were used at 30, 60, 90, 120, 150, 180, 210, 240, 270 ms of TE. This experiment was scanned with 5 steps from 25 to $45^{\circ}C$. next, using MRmap(Messroghli, BMC Medical Imaging, 2012) T1 and T2 relaxation times were mapped. on the Piview STAR v5.0(Infinitt, Seoul, Korea) 5 steps were measured as the same ROI, and then mean values were calculated. Correlation between the temperatures and relaxation times were analyzed by SPSS(version 17.0, Chicago, IL, USA). Results : According to increase of temperatures, T1 relaxation times were $214.39{\pm}0.25$, $236.02{\pm}0.87$, $267.47{\pm}0.48$, $299.44{\pm}0.64$, $330.19{\pm}1.72$ ms. T2 relaxation times were $180.17{\pm}0.27$, $197.17{\pm}0.44$, $217.92{\pm}0.39$, $239.89{\pm}0.53$, $257.40{\pm}1.77$ ms. With the correlation analysis, the correlation coefficients of T1 and T2 relaxation times were statistically significant at 0.998 and 0.999 (p< 0.05). Conclusion : T1 and T2 relaxation times are increased as temperature of tissue goes up. In conclusion, we suggest to recognize errors of relaxation time caused local temperature's differences, and consider external factors as well in the quantitative analysis of relaxation time or clinical tests.

사립유치원 경력 교사의 사직에 담긴 살아가는 이야기에 관한 내러티브 탐구

김호현(Kim, Ho-Hyun) 한국영유아교원교육학회 2020 유아교육학논집 Vol.24 No.1

이 연구는 10년의 유치원 경력을 가진 한 선생님의 사직 전과 후의 정체성 변화 과정과 사직의 의미를 내러티브 탐구의 살아가는 이야기와 개인적·전문적 지식 전경의 틀로 들여다보았다. 이를 위해 10년 동안 몸담았던 유치원을 그만두고 대학원에 진학한 김선생님과 아홉 차례 대화를 나누었고, 내러티브 탐구 방식으로 현장, 중간, 연구텍스트를 구성하였다. 김선생님은 교사 시절 개인적 전경과 전문적 전경이 충돌하는 과정에서 좌절과 허탈함을 겪었으나 이 충돌은 김선생님에게 교사가 되기 전 상상했던 유아를 변화시키는 좋은 교사가 될 기회가 되었고, 부모교육 강사의 꿈을 가지고 사직을 한 뒤 대학원에 진학하였다. 가르치는 자에서 배우는 자로, 유치원에서 대학원으로 역할과 장소가 바뀌고, 새로운 관계가 만들어지고, 경제적 어려움과 차별의 벽에 좌절하면서 정체성에도 변화가 생겼지만 유아를 변화시키는 좋은 교사가 될 것이라는 중추의 정체성을 유지함으로써 교사 시절부터 지금껏 전문적 전경의 삶을 살고 있다. 그의 사직에 담긴 살아가는 이야기는 더 큰 꿈을 향해 여행하는 성장에 관한 이야기이고, 유아를 위해 무엇을 할 것인가에 관한 답을 찾는 과정이었다. The study looked inside the changing identity of a former kindergarten teacher with 10 years of career experience before and after her resignation and the meaning of her resignation within the frames of stories to live by and personal-professional knowledge landscapes. Nine deep dialogues with the teacher, Kim, were conducted and a constructed field, interim, and final search text were made. Kim went through frustration and letdowns in the middle of conflicts between the personal and professional landscapes but this conflict was a good chance for her to be a good teacher who changed the children for the better, a story imagined before she became a teacher. She chose to resign and attend graduate school. Her identity changed as her role, place, and relationships shifted from teacher to learner, from the kindergarten to the tertiary-level classroom and being frustrated due to financial difficulties and barriers of discrimination. However sustaining her core identity as a good teacher who changed children for the better, she has been living on the professional landscape linked from the rookie teacher. Stories to live by embedded in Kim’s resignation stories are about the story of one teacher’s travelling for a better dream and a course of answering what to do for the children.

삼음삼양(三陰三陽)의 종화규율(從化規律)에 관한 연구(硏究)

김호현,Kim, Ho-Hyun 대한동의생리학회 1999 동의생리학회지 Vol.14 No.2

This study was undertaken to define the expression rule of six vital substances for human life(六氣) in Meridians and the rule of following of three ${\breve{U}}m$ and three Yan. In order to investigate the expression rule of six vital substances for human life(六氣), incident(標)-fundamental(本) and Ki of middle energizer(中氣) of three ${\breve{U}}m$ and three Yang(三陰三陽) were reviewed. 1, The rule of following is formed centering around fundamental Ki(本氣) between incident(標) and fundamental(本). And in case the ${\breve{U}}m$ and Yang (陰陽) disposition of incident(標) and fundamental(本) is different, whether the ${\breve{U}}m$ and Yang(陰陽) disposition of incident(標) and fundamental(本) is same as those of Ki of middle energizer(中氣), is the key point in following fundamental and activating of the vital energy(氣化). 2. As twelve channels(十二經脈) have not only fundamental Ki(本氣) but also Ki of middle energizer(中氣) at the same time, in expression of six vital substances for human life(六氣), if the fundamental Ki(本氣) is stronger, fundamental Ki(本氣) can be expressed or if the fundamental Ki(本氣) is weaker, Ki of middle energizer(中氣) can be expressed. 3. Twelve channels which is connected with each other through the relation of the interior and the exterior can be regarded as a system, in which Wind(風) and Fire(火), Dryness(燥) and Dampness(濕), Cold(寒) and Heat(熱) maintain balance through mutual control. 4. We can see that in the disease caused by the unbalance of six vital substances for human life(六氣), expression of six pathogenic factor and controlment of six vital substances for human life(六氣) are made up after the following one in the rule of following(從化規律).

라돈의 노출현황 및 정책방향 - 군부대 병영생활관 내 라돈 노출 현황

김호현,이동현,Kim, Ho-Hyeon,Lee, Dong-Hyeon 한국공기청정협회 2019 空氣淸淨技術 Vol.32 No.1

AI, 빅데이터 & IoT 공기산업의 현재와 전망 - 대학에서의 IoT 산업대응과 실내 공기산업

김호현,Kim, Ho-Hyeon 한국공기청정협회 2021 空氣淸淨技術 Vol.34 No.3

혈부축어탕이 Triton WR-1339에 의한 고지혈증 유발 생쥐 간조직내 지질 축적 억제에 미치는 영향

김호현,방혜정,강윤호,박인식,안상현,김진택,이해풍,Kim, Ho-Hyun,Bang, Hyui-Jeng,Gang, Yun-Ho,Park, In-Sick,Ahn, Sang-Hyun,Kim, Jin-Tack,Lee, Hai-Poong 대한동의생리학회 1999 동의생리학회지 Vol.14 No.2

After Triton WR-1339 (TX; 600mg/kg) intraperitoneal injection, hepatic tissues of ICR mice were intragastric injected with Hyulboochucketang extract(HCE; 3.3ml/kg/day) were observed to investigate the suppressive effect of lipid accumulation that evoke by the antihyperlipidemic effect of HCE. These hepatic tissues were fixed in fromol-calcium solution and were cryocut. These tissues stained by H&E for general morphology, sudan black B for lipid and perchloric acid-naphthoquinone(PAN) method for cholesterol. After TX treatment, the increase of hepatocyte having meshlike cytoplasm(HHMC) were shown in all hepatic lobules and the hepatic plates were disappeared in the aggregative region of HHMC. The number of blue black colored lipid drop and dark green colored asterisk shaped cholesterol particle in hepatic cytoplasm were increased and the size of lipid drop and cholesterol particle were enlarged. But, in HCE-treated mice, the HHCM were disappeared and hapatic plate were rearranged. The number of lipid drop and cholesterol particle were decreased than TX-treated mice and the size of lipid drop and cholesterol particle were diminished. As results indicated that the HCE work on the suppression of lipid accumulation in hepatic tissue of hyperlipidemic mice caused by disturbance of lipid metabolism.

서버 클러스터 환경에서 에너지 절약을 위한 서버 전원 모드 제어에서의 동적 종료

김호현,함치환,곽후근,정규식,Kim, Hoyeon,Ham, Chihwan,Kwak, Hukeun,Chung, Kyusik 한국정보처리학회 2013 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.2 No.7

기존 서버 클러스터에서는 고성능을 보장하기 위해, 실시간 요청 수량에 관계없이 모든 서버를 항상 On 한다. 그 방법에서는 QoS를 보장하지만 일부 서버들이 Idle할 때 서버 전력을 낭비하게 된다. 서버들이 소모하는 에너지를 절약하기 위해, 서버가 필요하지 않을 경우 해당 서버의 전력을 Off 하게 하는 서버 전력 제어 방법이 제안되었다. 서버 전력 제어 방법은 서버의 Power가 실제로 어느 시점에 Off 되느냐에 따라 정적인 방법과 동적인 방법이 있다. 정적인 방법에서는 특정 서버가 Off 하기로 결정된 다음 일정 시간 지연 후 그 서버가 Off 된다. 동적인 방법에서는 그 서버에서 수행중인 모든 서비스가 종료된 다음에 해당 서버가 Off 된다. 이는 가변 시간 지연 후 서버가 Off 되는 방법에 해당된다. 정적 종료방식은 단점이 있다. 반복 실험을 통해 수작업으로 최적의 시간 지연을 알아내기 위해서는 많은 시간이 소요된다. 본 논문에서는 정적 종료 방식의 단점을 극복하는 동적 종료 방식을 제안한다. 제안된 방식은 최적의 지연 시간으로 자동적으로 접근하므로 좋은 전력 절약을 하면서 QoS를 보장하는 것을 가능하게 해준다. 30대의 PC 클러스터를 이용하여 실험이 수행되었다. 실험결과는 제안하는 동적 종료 방법이 기존의 정적 종료 방법과 비교할 때 에너지 절감측면에서는 비슷하지만 QoS 측면에서 우수함을 보여준다. In order to ensure high performance, all the servers in an existing server cluster are always On regardless of number of real-time requests. They ensure QoS, but waste server power if some of them are idle. To save energy consumed by servers, the server power mode control was developed by shutdowning a server when a server is not needed. There are two types of server power mode control depending on when a server is actually turned off if the server is selected to be off: static or dynamic. In a static mode, the server power is actually turned off after a fixed time delay from the time of the server selection. In a dynamic mode, server power is actually turned off if all the services served in the server are done. This corresponds to a turn off after a variable time delay. The static mdoe has disadvantages. It takes much time to find an optimal shutdown time manually through repeated experiments. In this paper, we propose a dynamic shutdown method to overcome the disadvantages of static shutdown. The proposed method allows to guarantee user QoS with good power-saving because it automatically approaches an optimal shutdown time. We performed experiments using 30 PCs cluster. Experimental results show that the proposed dynamic shutdown method is almost same as the best static shutdown in terms of power saving, but better than the best static shutdown in terms of QoS.

도시철도와 실내환경 - 도시철도 내 미세먼지(PM10) 측정 신뢰성 확보

김호현,Kim, Ho-Hyeon 한국공기청정협회 2019 空氣淸淨技術 Vol.32 No.3

간이형 먼지센서 기술 - 간이형 IAQ센서 적용 사례 - 대중교통 중 시내버스 적용 사례를 중심으로 -

김호현,Kim, Ho-Hyeon 한국공기청정협회 2017 空氣淸淨技術 Vol.30 No.3

어린이 활동공간 중 스쿨존, 교사 내 미세먼지(<TEX>$PM_{10}/PM_{2.5}$</TEX>) 및 블랙카본(Black Carbon)의 노출과 인체유해성

김호현,Kim,Ho-Hyeon 한국방재학회 2014 한국방재학회지 Vol.14 No.2