급결제 및 혼화제 종류가 숏크리트 내구성에 미치는 영향에 관한 연구

백신원,권소진,이영수,김의성,신용석 한국안전학회 2003 한국안전학회지 Vol.18 No.3

Concrete and shotcrete should withstand the conditions for which they have been designed, without deterioration, over a period of years. But concrete and shotcrete are being deteriorated according to aging by internal and external causes. Recently, many studies on the durability of concrete have been conducted. But the durability of shotcrete is rarely studied. So, in this study, chloride ion penetration test, freeze and thaw test, neutralization test were conducted to examine the durability characteristics of shotcrete with several accelerator and chemical admixture types. These results indicate that shotcrete with alkali free accelerator and with superplasticizer are durable. Therefore, the present study provides a firm base to make high performance shotcrete.

국내 Epstein-Barr 바이러스 일차감염의 임상적 특성

김백남,곽이경,문치숙,김의석,박상원,이창섭 대한감염학회 2007 감염과 화학요법 Vol.39 No.6

In this study, the clinical features of 264 patients of primary Epstein-Barr virus (EBV) infection between the years of 2002-2006 were evaluated retrospectively. The median age of the patients was 6 years old (0-69), and the hospitalization rate was 78.0%. Fever (83.3%) and sore throat (50.4%) were the most common symptoms. Cervical lymphadenopathy (71.2%), tonsillitis (51.1%), splenomegaly (26.1 %), hepatomegaly (25.8%), rash (10.2%) and jaundice (1.5%) were observed. Cervical lymphadenopathy was less frequent in older age groups. The annual number of primary EBV infections according to the age group during the study period did not change significantly in this study.

쯔쯔가무시병에서 가피의 위치와 복장과의 관계

김백남,곽이경,문치숙,김의석,박상원,이창섭 대한감염학회 2006 감염과 화학요법 Vol.38 No.6

목적 : 쯔쯔가무시병의 예방을 위하여 위험지역에서 긴소매 윗옷을 입고 바지 끝을 양말 속에 넣는 것이 권장되고 있다. 이러한 예방조치의 효용성을 알아보기 위하여 우리는 쯔쯔가무시병에서 가피의 위치와 신발과 복장과의 관계를 살펴보았다. 재료 및 방법 : 2005년 10-12월 사이 6개 병원에서 전형적인 임상양상, 가피의 존재, 혈청검사 결과로 쯔쯔가무시병이 의심되거나 확진된 159명의 성인을 대상으로 가피의 위치, 추정 감염일, 야외활동, 당시 착용한 신발과 복장 등 을 조사하였다. 결과 : 혈청검사는 5명에서 시행되지 않았고 99명이 양성이었으며, 가피는 142명에서 발견되었다. 몸의 두 군데에서 발견된 6명을 제외한 136명 중 82명(60.3%)에서 가피는 하반신(아랫배, 엉덩이, 서혜부, 생식기, 넓적다리, 종아리)에 있었다. 감염일이 추정가능하고 가피가 1개만 있는 44명을 대상으로 하였을 때, 가피가 하반신에서 발견된 17명에서 슬리퍼를 신거나 맨발인 경우는 5명이었으나 상반신에 있는 27명 중에는 아무도 없었다(P=0.006). 바지아랫단을 양말 속에 집어 넣은 4명 중 1명은 하반신에서 3명은 상반신에서 가피가 발견되었다. 42명이 긴 소매 윗옷을 입었는데, 이중 16명은 하반신에서 26명은 상반신에서 가피가 발견되었다(P=1.00). 결론 : 쯔쯔가무시병 환자에서 신발을 신지 않거나 발이 잘 보호되지 않았을 때 가피는 하반신에 더 잘 생겼다. 바지 아랫단의 처리방법이나 긴 소매 윗옷의 착용은 가피의 위치와 통계적으로 유의한 연관관계는 발견되지는 않았다. 그러나 표본수가 적고 유충의 침범경로에 영향을 줄수 있는 다른 요인이 있기 때문에 가피의 위치와 연관관계가 없다고 이 연구에서 단정할 수는 없다. 따라서 쯔쯔가무시병의 예방을 위한 실용적인 권고를 위해서는 더 많은 연구가 필요하다. Background:Wearing a long-sleeved shirt and tucking the pants legs into the socks is recommended to prevent scrub typhus. This study investigated associations between the location of eschar and the type of clothes and shoes to evaluate the efficacy of these protective measures. Materials and Methods:One-hundred and fifty nine patients in whom scrub typhus was confirmed or suspected based on the typical clinical manifestations, presence of eschar, or positive results of serologic tests at 6 Korean hospitals from October to December 2005 were included in this study. We collected the information on the location of eschar, presumed exposure date to chiggers, and the clothes and shoes which they had worn. Results:Serologic tests were positive in 99 patients. Eschars were observed in 142 patients and 6 of them exhibited more than 2 eschars. Eighty-two (60.3%) of 136 patients with a single eschar had an eschar on the lower half of the body. Of the 44 patients whose exposure date could be estimated, and who had only a single eschar, 5 of the 17 patients with eschars in the lower half of their bodies, and none of the 27 patients with eschars in the upper half of their bodies went barefoot or wore open footware (P=0.006). Only 4 patients tucked the pants into their socks, and an eschar was found in the lower half in one patient, and in the upper half of the body in the other 3 patients. Of 42 patients who wore long-sleeved shirts, eschars were found in their lower bodies in 16, and on their upper bodies in 26 (P=1.00). Conclusion:When the feet were not protected properly with shoes, eschars were found more frequently on the lower half of the body than on the upper half. Wearing a long-sleeved shirt or tucking the pants legs into the socks was not found to be significantly correlated to the location of eschars. Further studies involving larger samples are necessary for the development of practical guidelines of protective measures to prevent scrub typhus.

발작과 쇼크를 동반한 토착형 삼일열 말라리아 1예

윤상구,김민환,정은숙,한금현,곽이경,조종래,엄태현,김의석 대한감염학회 2007 감염과 화학요법 Vol.39 No.4

삼일열 말라리아는 일반적으로 경미한 임상경과를 거치며, 열대열 말라리아와 달리 뇌형말라리아, 폐부종, 신부전등의 치명적인 합병증을 일으키지 않는 것으로 알려져 있다. 저자들은 특이한 과거력이 없던 건강하던 성인이 국내에서 삼일열 말라리아에 걸린 후 발작과 쇼크가 발생하여, 항말라리아 약제와 대증치료로 치료된 증례를 경험하였다. Vivax malaria reemerged in the Republic of Korea in 1993. Vivax malaria is generally a benign disease with few severe complications. Even in the worldwide literature, there is only a small number of case reports on severe complications in vivax malaria. We report a unique case of P. vivax infection complicated by seizure and shock. A 58 year-old male showed generalized tonic-clonic seizure and shock after P. vivax infection. The species of malarial parasite was identified using peripheral blood film examination and polymerase chain reaction (PCR). He successfully recovered after treatment with hydroxychloroquine.

An Improved Integer Frequency Offset Estimation Scheme for OFDM systems

Eu-Suk Shim,Young-Hwan You 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7

Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to carrier frequency offset. This paper deals with estimation method of integer frequency offset (IFO) with improved performance. The proposed IFO estimator exploits two consecutive identical OFDM data symbols with only change of phase. To demonstrate the efficiency of the proposed IFO estimators, comparisons are made with other existing estimator in terms of error performance.

OFDM Carrier Frequency Offset Estimation Methods With Improved Performance

Eu-Suk Shim,Sang-Tae Kim,Hyoung-Kyu Song,Young-Hwan You [Institute of Electrical and Electronics Engineers 2007 IEEE transactions on broadcasting Vol.53 No.2

<P>Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to carrier frequency offset and symbol timing error. This paper deals with estimation method of integer frequency offset (IFO) without the aid of pilot symbols. The proposed IFO estimator exploits two consecutive identical OFDM data symbols with only change of phase. In order to improve the accuracy of the IFO estimator, receive diversity is adopted. To demonstrate the efficiency of the proposed IFO estimators, comparisons are made with other existing estimators in terms of error performance, estimation range, and complexity.</P>

Low-cost integer frequency offset estimation for OFDM-based DRM receiver

Eu-Suk Shim,Joonbeom Kim,Young-Hwan You IEEE 2010 IEEE transactions on consumer electronics Vol.56 No.4

<P>In this paper, we propose an improved and low-cost integer frequency offset (IFO) estimation method by partitioning pilot symbols effectively in an orthogonal frequency division multiplexing based digital radio mondiale (DRM) system. To this end, the time reference cell (TRC) symbol for frequency estimation is grouped into a number of pilot clusters, so that the TRC subcarriers in each cluster are closely spaced to show approximately frequency-nonselective characteristics. The performance of the proposed IFO estimator is compared with that of the conventional estimator, and shows that the proposed technique can effectively achieve lower estimation errors in frequency offset estimation as well as can be implemented with reduced computational complexity.</P>

Clinical Course and Outcomes of Patients with Severe Acute Respiratory Syndrome Coronavirus 2 Infection: a Preliminary Report of the First 28 Patients from the Korean Cohort Study on COVID-19

Eu Suk Kim,Bum Sik Chin,강창경,Nam Joong Kim,Yu Min Kang,Jae-Phil Choi,Dong Hyun Oh,Jeong-Han Kim,Boram Koh,Seong Eun Kim,Na Ra Yun,Jae Hoon Lee,Jin Yong Kim,Yeonjae Kim,Ji Hwan Bang,송경호,Hong Bin Kim,Ki- 대한의학회 2020 Journal of Korean medical science Vol.35 No.13

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected pneumonia emerged in Wuhan, China in December 2019. In this retrospective multicenter study, we investigated the clinical course and outcomes of novel coronavirus disease 2019 (COVID-19) from early cases in Republic of Korea. Methods: All of the cases confirmed by real time polymerase chain reaction were enrolled from the 1st to the 28th patient nationwide. Clinical data were collected and analyzed for changes in clinical severity including laboratory, radiological, and virologic dynamics during the progression of illness. Results: The median age was 40 years (range, 20–73 years) and 15 (53.6%) patients were male. The most common symptoms were cough (28.6%) and sore throat (28.6%), followed by fever (25.0%). Diarrhea was not common (10.7%). Two patients had no symptoms. Initial chest X-ray (CXR) showed infiltration in 46.4% of the patients, but computed tomography scan confirmed pneumonia in 88.9% (16/18) of the patients. Six patients (21.4%) required supplemental oxygen therapy, but no one needed mechanical ventilation. Lymphopenia was more common in severe cases. Higher level of C-reactive protein and worsening of chest radiographic score was observed during the 5–7 day period after symptom onset. Viral shedding was high from day 1 of illness, especially from the upper respiratory tract (URT). Conclusion: The prodromal symptoms of COVID-19 were mild and most patients did not have limitations of daily activity. Viral shedding from URT was high from the prodromal phase. Radiological pneumonia was common from the early days of illness, but it was frequently not evident in simple CXR. These findings could be plausible explanations for the easy and rapid spread of SARS-CoV-2 in the community.

Pilot Subset Partitioning Based Integer Frequency Offset Estimation for OFDM Systems With Cyclic Delay Diversity

Eu-Suk Shim,Hyoung-Kyu Song,Young-Hwan You IEEE 2010 IEEE transactions on broadcasting Vol.56 No.4

<P>Cyclic delay diversity (CDD) is a simple transmit diversity technique for coded OFDM systems with multiple transmit antennas. However, high frequency selectivity caused by CDD degrades the performance of post- FFT estimation, i.e., integer frequency offset (IFO). This paper suggests a simple way of improving the performance of the IFO estimator based on the pilot subset partitioning which is designed to reduce the effect of frequency selective fading by adopting the CDD. By partitioning uncorrelated pilot subcarriers into subsets to satisfy high correlation, and performing frequency estimation for each pilot subset, a robust IFO estimation scheme is derived. The simulation results show that the proposed method can provide benefit to the overall system performance .</P>

Low-Complexity Coarse Frequency Offset Estimation for OFDM Systems with Non-uniform Phased Pilots

SHIM, Eu-Suk,YOU, Young-Hwan The Institute of Electronics, Information and Comm 2011 IEICE transactions on fundamentals of electronics, Vol.ea94 No.2

<P>In this letter, we propose a low-complexity coarse frequency offset estimation scheme in an orthogonal frequency division multiplexing (OFDM) system using non-uniform phased pilot symbols. In our approach, the pilot symbol used for frequency estimation is grouped into a number of pilot subsets so that the phase of pilots in each subset is unique. We show via simulations that such a design achieves not only a low computational load but also comparable performance, when compared to the conventional estimator.</P>