터널 영구 지보재로서의 숏크리트 고성능화 및 내구성 평가에 관한 연구

이상필(Sang-Pil Lee),류종현(Jong-Hyun Ryu),이상돈(Sang-Don Lee),전석원(Seokwon Jeon),이정인(Chung-In Lee) 한국암반공학회 2007 터널과지하공간 Vol.17 No.4

최근 국내 터널 분야에서는 현장타설 콘크리트 라이닝을 생략한, 이른바 무라이닝 터널을 적용하려는 시도가 수차례 있었으나 숏크리트가 영구 지보재로서의 성능을 확보하고 있는지에 대한 의구심으로 인해 시공으로는 이어지지 못하고 있다. 숏크리트는 시공 상 문제뿐만 아니라 강도기준이 유럽에 비해 현저히 낮고 내구성에서도 많은 문제를 내포하고 있는 것으로 파악되고 있다. 본 연구에서는 효율적인 배합개선을 통하여 압축강도 40 ㎫, 휨강도 4.5 ㎫ 이상의 고강도 숏크리트를 개발하였으며 급결제 종류와 실리카퓸 첨가량을 주 변수로 하여 최대 2년까지의 성능변화 추이를 분석하였다. 또한 단기 내구성 평가를 위해서는 동결융해, 중성화, 염해에 따른 실험실 촉진 실험과 투수시험을 실시하였으며 장기 내구성 검증을 위해서는 실제 운영 중인 고속도로 터널 내에 시편을 적치하여 복합 환경에 대한 영향을 조사하였다. 분석결과 알칼리프리계만이 유일하게 고강도 목표기준을 만족하였으며, 또한 개발된 고성능 숏크리트가 내구성에 있어서도 매우 우수한 것을 확인하였다. Recently, many efforts have been made to construct the first unlined tunnel, without in-situ concrete lining, in Korea. However, the lack of reliability in the performance of shotcrete as permanent tunnel support prevented from its realization. Shotcrete has been regarded to have significant problems in field application and long term performance because of unsatisfactory strength level and durability compared to those of European countries. In this study, the high strength shotcrete satisfying compressive strength over 40 ㎫ and flexural strength over 4.5 ㎫ was developed from optimized mix design. The type of accelerators and the amount of silica fume were selected as the main factors in mixing process and the analyses were carried out up to the elapsed time of 2 years. In order to evaluate the short term durability of shotcrete, an array of laboratory test consisting of freeze-thaw, carbonation, chloride penetration and permeability test was performed. For long-term durability tests, specimens have been put in an operated highway tunnel to expose them to the similar environment when they are actually used as an unlined tunnel support. From the strength and durability tests, it was found that only alkali-free based accelerator satisfied the target strength of this study and also, the developed shotcrete showed very high performance in its durability.

LETTER TO THE EDITOR : Adrenocorticotropic hormone-independent macronodular adrenal hyperplasia with abnormal cortisol secretion mediated by catecholamines

( Harin Rhee ),( Yun Kyung Jeon ),( Sang Soo Kim ),( Yang Ho Kang ),( Seok Man Son ),( Yong Ki Kim ),( In Joo Kim ) 대한내과학회 2014 The Korean Journal of Internal Medicine Vol.29 No.5

Adrenocorticotropic hormone (ACTH)- independent macronodular adrenal hyperplasia (AIMAH) is a rare cause of Cushing syndrome. In AIMAH, cortisol secretion is independent of ACTH, and various hormones and/or cytokines have been thought to stimulate cortisol secretion via the aberrant expression of adrenal receptors or the increased activity of eutopic hormone receptors. Schorr and Ney [1] f irst proposed this concept, and subsequently the ectopic expression of gastric inhibitory peptide (GIP), V2 and V3-vasopressin, β -adrenergic, luteinizing hormone (LH)/human chorionic gonadotropin (hCG), serotonin, and angiotensin receptors, as well as increased activity of a eutopic V1-vasopressin receptor, have been identified in the adrenal gland [1,2]. Several genetic factors, such as Gs α-subunit mutations associated with McCune-Albright syndrome and MC2R (ACTH receptor gene) mutations, have also been postulated as causes of AIMAH. A 50-year-old male was referred and admitted to our hospital due to uncontrolled hypertension. He had suffered from hypertension for 6 years. His blood pressure was originally well controlled for the first 5 years using a calcium channel blocker, but poorly controlled for 1 year before he visited our hospital, despite his regular use of antihypertensive agents. He was initially referred to the Cardiology Department and underwent cardiologic evaluation after complaining of paroxysmal palpitation and dizziness. His 24-hour Holter monitoring and coronary angiographic results were normal, except for several antigen- presenting cells and a minimal coronary arterial obstruction at the middle left anterior descending artery. He had a past history of major depression and had been prescribed an antidepressive agent 18 months before he visited our hospital. On physical examination, he had a moon face, marked central obesity (height, 167 cm; weight, 77.65 kg; body mass index, 27.84 kg/m2), and multiple bruises on his extremities. He also had prominent purple abdominal striae, and all of his morphological features were consistent with Cushing syndrome. Laboratory examinations revealed 145.7 mEq/L serum sodium and 2.86 mEq/L serum potassium. Arterial blood gas analysis revealed metabolic alkalosis (pH 7.519, HCO3, 37.4 mM/L). His hemoglobin A1c level was 5.9%, and his serum fasting blood glucose was 118 mg/dL. The results of basal endocrinological examinations are summarized in Table 1. The circadian variation in serum cortisol production was disrupted, and basal ACTH levels were suppressed. A 24-hour urinary free cortisol test and overnight dexamethasone suppression test (DMST) were both suggestive of Cushing syndrome. Low- and high-dose DMST revealed Cushing syndrome of primary adrenal origin. An abdominal computed tomography scan and magnetic resonance imaging (MRI) revealed bilateral large macronodular adrenal tumors. His pituitary gland was normal on brain MRI scans. We thus diagnosed this patient with Cushing syndrome secondary to AIMAH. To identify aberrant receptors on the adrenal gland, we followed the investigative protocol described by Lacroix et al. [3]. Postural and various provocation tests, including ACTH (250 μg, intravascular), arginine vasopressin (AVP; 10 IU, intramuscular), 5-hydroxy triptamine (5-HT; 10 mg, intravascular), isoproterenol (20 ng/kg/min, intravascular for 30 minutes) and mixed meal tests, were performed. His serum cortisol level showed a positive response to ACTH, AVP, and isoproterenol provocation tests, but a negative response to the postural stimulation test. The results are summarized in Fig. 1A. If the patient had β-adrenergic or AVP receptors on his adrenal gland, then he would have responded to the postural stimulation test; but he did not. We repeated the postural stimulation test, and checked his endogenous antidiuretic hormone (ADH) level. He exhibited an increased ADH level on the postural test, but no cortisol secretion (Fig. 1B). A bilateral adrenalectomy was performed. The subsequent pathological examination of both adrenal glands showed hyperplasia with a multinodular growth pattern: the right and left adrenal glands were sized 14.0 × 5.0 × 3.0 cm and 9.0 × 5.0 × 3.0 cm, respectively, and multiple golden yellow nodules measuring up to 4 cm in diameter were present. Microscopic findings showed that the nodules consisted of variable- sized nests of lipid-laden clear cells similar to those of the normal fasiculata layer (Fig. 2). The final clinical and pathological diagnosis was Cushing syndrome secondary to β-adrenergic agonist-responding AIMAH. After the operation, he took physiological doses of prednisolone and f ludrocortisone. He then lost weight gradually and achieved optimal blood pressure with reduced doses of antihypertensive agents. Kirschner et al. [4] first described AIMAH in 1964. They demonstrated that hypercortisolism was ACTH-independent, and that the resected adrenal glands contained multiple nodules. Since then, a number of cases have been described, and the cause of AIMAH has been characterized more precisely. Previously, steroid production in AIMAH was believed to be autonomous. In the previous study that compared the adrenal glands of patients with AIMAH to those in patients with long-standing Cushing disease, and concluded that prolonged adrenal stimulation by ACTH resulted in adrenal bilateral nodular formation and varying ranges of adrenal autonomy [5]. There were also some cases in which autonomy of the adrenal gland was the result of chronic ACTH stimulation, which eventually resulted in ACTH suppression. However, the rarity of Nelson syndrome following bilateral adrenalectomy in patients with AIMAH strongly argued against the adrenal autonomy hypothesis. In 1971, Schorr and Ney [1] first introduced the concept of aberrant adrenal receptor expression in adrenocortical tissue. They performed in vitro studies, and found that cyclic adenosine monophosphate and corticosterone production in rat adrenocortical carcinoma cells were stimulated by non-ACTH hormones such as catecholamines, thyroid stimulating hormone, follicle stimulating hormone, LH, and prostaglandin E1. This hypothesis was later validated in humans by additional in vitro and in vivo studies. Several ectopic receptors such as GIP, β-adrenergic receptors, vasopressin (V2-V3-vasopressin receptor), serotonin (5-HT7 receptors), and angiotensin II receptors, and increased expression or altered activity of eutopic receptors in- cluding the V1-vasopressin receptors, LH/hCG receptors, serotonin (5-HT4 receptor), and leptin receptors was found [5]. In our patient, the serum cortisol level was increased by ACTH stimulation, exogenous AVP, and isoproterenol. Because exogenous AVP could naturally stimulate ACTH and increase serum cortisol levels, we checked serum ACTH levels during an AVP stimulation test. His serum cortisol level was increased by 82%, and serum ACTH level was increased by 11.5%. We were unable to confirm if AVP itself stimulated the adrenal cortex directly, or whether the induced ACTH caused cortisol secretion. A postural test was performed to screen for the aberrant expression of the AVP, β-adrenergic, or angiotensin II receptors. Interestingly, cortisol secretion was stimulated by exogenous AVP and a β-adrenergic agonist; however, a postural test failed to stimulate cortisol secretion. We repeated the postural test, and also checked the patient`s aldosterone level to verify if the test was accurate and determined serum ADH levels to confirm if endogenous ADH stimulated adrenal cortisol secretion. Because serum aldosterone levels increase in response to postural stimulation, the test itself was working; however, the cortisol response was negative. This suggests that the patient`s β-adrenergic receptor showed a blunted response to the test. Because we did not determine the serum catecholamine levels during postural stimulation, it was unclear whether the postural test induced sufficient endogenous catecholamine. Although a stronger stimulus (such as a treadmill test) would have induced endogenous catecholamine and increased serum cortisol levels, the patient refused because he had ischemic heart disease. In our case, exogenous AVP, but not endogenous ADH, stimulated adrenal cortisol secretion. This suggests that the cortisol response to exogenous pharmacological levels of vasopressin was mediated by AVP-induced catecholamine release [3]. We finally concluded that this patient had ectopic β-adrenergic receptors on the adrenal cortex, and recommended long-term propranolol therapy. However, because he strongly desired to undergo treatment with a rapid response, we consulted the Urological Department who recommended bilateral adrenalectomy. The identification of aberrant adrenal hormone receptors in AIMAH provides novel opportunities for specific pharmacological therapies as alternatives to adrenalectomy. In 1997, Lacroix et al. [3] reported the use of propranolol therapy for ectopic β-adrenergic receptors in adrenal Cushing syndrome in 1997. Some studies have revealed aberrant receptor expression in vitro using reverse transcription polymerase chain reaction. However, a limitation of our study is that we did not confirm aberrant receptor expression using in vitro analyses. In conclusion, we report a rare case of an AIMAH patient. In vivo examinations suggested that altered cortisol regulation due to a β-adrenergic agonist was involved in the pathogenesis of the AIMAH patient.

Low serum bilirubin level predicts the develop-ment of chronic kidney disease in patients with type 2 diabetes mellitus

( Kang Hee Ahn ),( Sang Soo Kim ),( Won Jin Kim ),( Jong Ho Kim ),( Yun Jeong Nam ),( Su Bin Park ),( Yun Kyung Jeon ),( Bo Hyun Kim ),( In Joo Kim ),( Yong Ki Kim ) 대한내과학회 2017 The Korean Journal of Internal Medicine Vol.32 No.5

Background/Aims: We evaluated whether serum bilirubin levels can predict the development of chronic kidney disease (CKD) in patients with type 2 diabetes mellitus (T₂DM). Methods: This was a retrospective observational longitudinal study of patients presenting at the Pusan National University Hospital. A total of₃₄₉ patients with T₂DM and preserved kidney function (estimated glomerular filtration rate ≥ 60 mL/min/1.73 m²) were enrolled. The main outcome was the development of CKD stage 3 or greater. The patients were divided into four groups according to the quartiles of the total serum bilirubin levels at baseline. Results: The group with the lowest range of total serum bilirubin level (Q₁) showed the highest cumulative incidence of CKD stage 3 or greater than that of the other lower quartiles (Q₁ vs. Q₄; hazard ratio [HR], 6.75; 95% confidence in-terval [CI], 1.54 to 29.47; p = 0.011). In multivariate analysis, the risk of developing CKD stage 3 or greater was higher in the second lowest quartile of the serum bili-rubin level than that in the highest quartile of the serum bilirubin level (Q₂ vs. Q₄; HR, 9.36; 95% CI, 1.33 to 65.73; p = 0.024). In the normoalbuminuria subgroup (n = 236), multivariate analysis showed that the risk of developing CKD stage 3 or greater was higher in the lowest quartile of the serum bilirubin level than that in the highest quartile of the serum bilirubin level (Q1 vs. Q4; HR, 7.36; 95% CI, 1.24 to 35.82; p = 0.019). Conclusions: Serum bilirubin might be an early clinical marker for predicting the progression of CKD in patients with T₂DM and preserved renal function.

DYNAMIC RESPONSE OF CARBON NANOTUBES DISPERSED IN NEMATIC LIQUID CRYSTAL

YOUNG HEE LEE,SANG YOUN JEON,KYUNG AH PARK,IN-SU BAIK,SEOK JIN JEONG,SEOK HO JEONG,안계혁,SEUNG HEE LEE 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2007 NANO Vol.2 No.1

The alignment and dynamic response of carbon nanotubes (CNTs) in nematic liquid crystal (NLC) medium induced by strong electric field have been observed through polarizing optical microscope. Density-functional calculations suggest that LC molecule anchors helically to the CNT wall to enhance π-stacking with a binding energy of nearly -2.0 eV due to a considerable amount of charge transfer from LC molecule to CNT, resulting in the formation of excess charges and permanent dipole moment in CNTs. Under strong electric field, the motion of CNTs distorted the director of adjacent LC molecules. Our detailed analysis of dynamics revealed that the four-lobe textures in vertical cell and two vertical stripes in in-plane switching cell were strongly correlated, i.e., the side view of textures by the vertical motion of CNTs in vertical cell was similar to the textures in in-plane switching cell. Interestingly, the magnitude of textures in microscope was strongly dependent on the size of CNTs and theapplied field strength. The statistical size distribution of textures similar to that of CNTs provided information for the degree of dispersion of CNTs.

유류비축기지 설계를 위한 대심도 경사공에서의 수압파쇄 초기응력 해석

최성웅,신희순,박찬,신중호,배정식,이형원,박종인,전한석,Choi, Sung-Oong,Shin, Hee-Soon,Park, Chan,Syun, Joong-Ho,Bae, Jeong-Sik,Lee, Hyeong-Won,Park, Jong-In,Jeon, Han-Seok 한국지반공학회 1999 한국지반공학회논문집 Vol.15 No.4

유류비축용 지하저장공동의 설계를 위하여 수압파쇄시험에 의한 현지암반내 초기응력 해석이 수행되었다. 부지 내 2개의 경사 시추공에 대해 수행된 금번 시험은 국내 기술진에 의한 지하비축기지 적용의 첫 사례이다. 또한, 경사공 해석기법을 처음으로 도입하여 수직공 해석기법에 의한 결과와 비교, 해석기법의 타당성을 검증함으로써 향후 수압파쇄시험의 적용범위 확대를 기대할 수 있었다. 특히 인근 지역이라도 지형적 또는 지질학적 특성에 따라 초기응력의 크기는 달라질 수 있음을 보여주었으며, 동일 시추공 내에서라도 구조선 등과 같은 뚜렷한 불연속면이 있을 경우초기응력의 방향이 심도에 따라 변화될 수 있음을 보여주었다. Hydraulic fracturing tests were performed in two inclined boreholes for the design of underground oil storages in Korea. Extensions of their application limits were expected through a precise comparison between the interpretation techniques for the vertical and the inclined boreholes. Especially, it was verified that the magnitude of in-situ stress can be varied even in the same rock mass with a variety of geographic/geotechnical characteristics. It was also demonstrated that its orientation can be changed even in the same borehole with the existence of explicit discontinuities.

In-situ Test of ZigBEE System for Wireless Vibration Monitoring

Seo Il Chang(장서일),HyeSung Jeon(전혜성),In Jang Hwang(황인장),Sung-Hwan Jung(정성환) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.10

Motion of Charged Micro-particle Immersed in Liquid Crystal Controlled by In-plane Field for Electro Paper Display

In-Su Baik,송은경,이승희,Ju-Hwan Choi,Byoung Sun Jung,Sang Youn Jeon 한국전기전자재료학회 2006 Transactions on Electrical and Electronic Material Vol.7 No.1

We have studied the motion of charged micro-particles that are immersed in a nematic liquid crystal (LC) and controlled by in-plane field. The LC is an anisotropic liquid such that the viscosity of the LC depends on flow direction, phase of the LC, and temperature, which affects the motion of the charged particles under the influence of electric field. This study shows that the motion of charged particles mainly depends on the applied voltage and the LC phase, but does not show any significant influence from the initial alignment of LC, although one may expect directional difference in drag force due to interaction between LC and particle. The viscosity changes due to temperature variations in nematic phase also show no signification influence on particle velocity when compared to the effect from varying in-plane field strength.

32-bit 임베디드 시스템을 이용한 자동변속기용 전자제어시스템의 Software-in-the-loop simulation

장인규(In-Gyu Jang),서인근(Inkeun Seo),전재욱(Jaewook Jeon),황성호(Sung-Ho Hwang) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Drivers are becoming more fatigued and uncomfortable as traffic densities increase, which can lead to slower reaction time, They then face the danger of traffic accidents due to an inability to cope with frequent shifting, To reduce this risk some drivers prefer automatic transmissions (AT) to manual transmissions (MT), The AT is superior drivability and less shifting shock than the MT, so the market-share of AT is increasing, The AT is controlled by Electronic Control Unit (ECU) to obtain better shifting performance, The Transmission Control Unit (TCU) is a product of higher-value-added, so the companies which have advanced technology (BOSCH, SIEMENS VDO, DELPHI, and etc.) tend to evade technology transfer. As the number of ECU used on a car is increasing gradually (for example, engine management unit, transmission control unit, brake control unit, and powertrain control unit), TCU's performance is expected to be faster and more efficient for organic communication and arithmetic processing between the control systems than the performance of 16bit controller. In this paper, the model of automatic transmission vehicle using MATLAB/Simulink is developed for the hardware in-the-loop simulation with an embedded system. The AT control logic developed is loaded to 32-bit Embedded system platform developed on the basis of Freescale's MPC565, and we execute the Software-in-the-loop simulation (SILS) of AT based on Real Time Operating System (RTOS). These test results show that the developed embedded system can be used as AT control unit.

발전소 온배수 영향 저감을 위한 냉각방식 개선 타당성 조사연구

전인성(In-sung Jeon),박석순(Seok-Soon Park),정연태(Yeon-Tae Jeong),임주환(Ju-Hwan Lim),강연식(Yeon-Shik Kang),길준우(Joon-Woo Gil) 한국해양환경·에너지학회 2009 한국해양환경·에너지학회 학술대회논문집 Vol.2009 No.11월

국내 대부분의 발전소는 해안가에 위치하여 전력생산을 위한 냉각 계통수로 많은 양의 해수를 사용하고 있으며, 일과식 냉각방식(Once-through Cooling System)을 채택하고 있다. 일과식 냉각방식은 현존하는 냉각방식 중에서 가장 효과적이나 사용된 온배수가 해역으로 직접 배출되므로 수온상승에 따른 환경적인 문제를 발생시킨다. 이의 해결을 위해서 최근에 건설된 신규발전소의 경우 저층 취ㆍ배수(Seafloor In-Outlet System)를 채택하고 있으나, 이 역시 저층 생태계에 대한 피해를 배제할 수는 없다. 본 연구에서는 가동 중인 발전소의 냉각방식 개선대안을 저층 취ㆍ배수 방식, 습건식 냉각탑 방식, 순환 냉각수 공랭 방식, 냉각지 방식 등으로 구분하고 각각의 개선방법을 기술성 검토, 소요부지 및 용수확보 분석, 개선에 따른 효과분석, 공사로 인한 전력수급영향을 고려하여 분석하였으며 각각의 대안에 대한 개선비용을 산출하고 이를 토대로 기존 발전소의 냉각방식 개선 타당성을 검토하였다. 검토결과, 기존 발전소의 냉각설비 개선은 많은 부지가 소요되고 용수의 확보가 곤란한 것으로 조사되었다. 또한 공사에 따른 발전 손실과 전력계통에 미치는 영향과 공사비용을 고려할 때 개선방법의 총비용 대비 효과 측면에서 다소 비현실적으로 검토되었다. Most large-scale power plants are located on the seashore and use a lot of seawater for their once-through cooling system. Once-through cooling system seems to be most efficient but can affect marine ecosystem by the thermal water. Recently, newly constructed plants select seafloor in-outlet system to minimize influenced area but it also may cause environmental problems of the seafloor ecosystem. The alternative cooling methods considered in this study were seafloor in-outlet system, cooling tower system, dry cooling system and cooling pond system. In this study, those methods were investigated from the viewpoint of applicability, operating area and water, effectiveness and benefit, terms for construction and power supply influence. All cost were evaluated and it is concluded that there were no applied cases in/outside country and not available on a basis of cost and benefit

Motion of Charged Micro-particle Immersed in Liquid Crystal Controlled by In-plane Field for Electro Paper Display

Baik, In-Su,Choi, Ju-Hwan,Jung, Byoung-Sun,Jeon, Sang-Youn,Song, Eun-Kyoung,Lee, Seung-Hee The Korean Institute of Electrical and Electronic 2006 Transactions on Electrical and Electronic Material Vol.7 No.1

We have studied the motion of charged micro-particles that are immersed in a nematic liquid crystal (LC) and controlled by in-plane field. The LC is an anisotropic liquid such that the viscosity of the LC depends on flow direction, phase of the LC, and temperature, which affects the motion of the charged particles under the influence of electric field. This study shows that the motion of charged particles mainly depends on the applied voltage and the LC phase, but does not show any significant influence from the initial alignment of LC, although one may expect directional difference in drag force due to interaction between LC and particle. The viscosity changes due to temperature variations in nematic phase also show no signification influence on particle velocity when compared to the effect from varying in-plane field strength.