• Journal of KIISE
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• v.42 no.7
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• pp.919-928
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• 2015

In recent years, many research efforts have been made on privacy-preserving data mining (PPDM) in data of large volume. In this paper, we propose a PPDM solution based on principal component analysis (PCA), which can be widely used in computing correlation among sensitive data sets. The general method of computing PCA is to collect all the data spread in multiple nodes into a single node before starting the PCA computation; however, this approach discloses sensitive data of individual nodes, involves a large amount of computation, and incurs large communication overheads. To solve the problem, in this paper, we present an efficient method that securely computes PCA without the need to collect all the data. The proposed method shares only limited information among individual nodes, but obtains the same result as that of the original PCA. In addition, we present a dimensionality reduction technique for the proposed method and use it to improve the performance of secure similar document detection. Finally, through various experiments, we show that the proposed method effectively and efficiently works in a large amount of multi-dimensional data.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.3
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• pp.879-886
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• 2018

The basic search engine on Twitter shows not only tweets that contain search keywords, but also all articles written by users with nicknames containing search keywords. Since the tweets unrelated to the search keyword are exposed as search results, it is inconvenient to many users who want to search only tweets that include the keyword. To solve this inconvenience, this study improved the search function of Twitter by developing an algorithm that searches only tweets that contain search keywords. The improved functionality is implemented as a Web service using ASP.NET MVC5 and is available to many users. We used a powerful collection method in C# to retrieve the results of an object, and it was also possible to output them according to the number of 'retweets' or 'favorites'. If the number of retrieved numbers is less than a given number, we also added an exclusion filter function. Thus, sorting search results by the number of retweets or favorites, user can quickly search for opinions that are of interest to many users. It is expected that many users and data analysts will find the developed function convenient to search on Twitter.

• Information Systems Review
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• v.9 no.2
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• pp.41-66
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• 2007

The e-marketplace is a virtual marketplace where buyers and sellers meet in order to conduct transactions through the intermediation of market-makers. For the success of an e-marketplace, it is crucial for the market-maker to induce both buyers and sellers to make active transactions in it. However, their participation is frequently deterred by potential risk factors caused mainly by the inherent, structural complexity of the e-marketplace. Therefore, it is a critical challenge for the market-maker to identify and manage the transactional risk perceived by both the buyers and sellers. In this paper, we investigate the sources of buyers' and sellers' perceived risks and their mitigating factors in the e-marketplace. Specifically, we derive an analysis framework based on the economic theory of agency relationship. The framework includes four sources of the risks(perceived information asymmetry, fears of seller opportunism, fears of buyer opportunism, and concerns about market-maker's role incompleteness) and five mitigators of the risks(website informativeness, trust in market-maker, trust in seller, product diagnosticity, and social presence). Then, we empirically verify the framework through a case study on four successful e-marketplaces, and provide implications and strategies for the market-maker to effectively manage the transactional risks.

• The Korean Journal of Nuclear Medicine
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• v.34 no.2
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• pp.144-153
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• 2000

Purpose: The purpose of this study was to evaluate the relationship between radiation-induced activation of DNA repair genes and radiation induced apoptosis in A431 cell line. Materials and Methods: Five and 25 Gys of gamma radiation were given to A431 cells by a Cs-137 cell irradiator. Apoptosis was evaluated by flow cytometry using annexin V-fluorescein isothiocyanate and propidium iodide staining. The expression of DNA repair genes was evaluated by both Northern and Western blot analyses. Results: The number of apoptotic cells increased with the increased radiation dose. It increased most significantly at 12 hours after irradiation. Expression of p53, p21, and hRAD50 reached the highest level at 12 hours after 5 Gy irradiation. In response to 25 Gy irradiation, hRAD50 and p21 were expressed maximally at 12 hours, but p53 and GADD45 genes showed the highest expression level after 12 hours. Conclusion: Induction of apoptosis and DNA repair by ionizing radiation were closely correlated. The peak time of inducing apoptosis and DNA repair was 12 hours in this study model. hRAD50, a recently discovered DNA repair gene, was also associated with radiation-induced apoptosis.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.241-245
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• 2007

국내 홍수빈도 분포의 매개변수 추정에서 지점추정(at-site estimate) 방법은 유량 자료의 부족으로 발생하는 표본오차(sampling error)가 크기 때문에 충분한 유량 자료를 보유한 지점에 한하여 제한적으로 사용되고 있다. 대안으로 동질성을 가진 유역의 유량 자료를 모아 지역 매개변수를 추정하는 지수홍수법(Index Flood Method)이 제안되기도 하였으나, 이질성이 큰 우리나라의 유역특성 때문에 적용이 쉽지 않다. Stedinger와 Tasker가 1986년 제안한 GLS(Generalized Least Square) 기법은 유역을 동질지역으로 구분할 필요가 없으며 지점들간의 상관관계와 이분산성을 고려할 수 있어, 국내 홍수빈도 해석을 위해서 꼭 도입해야할 기법으로 생각된다. 본 연구에서는 기존의 GLS 기법의 단점을 보완한 Bayesian-GLS 기법을 이용하여, 국내 대유역에 골고루 위치하며 댐의 영향을 받지 않는 31개 지점의 연최대 일유량 시계열의 L-변동계수(L-moment coefficient variation)와 L-왜도계수(L-moment coefficient skewness)를 추정할 수 있는 회귀모형을 제안하였다. 위 회귀모형을 구성하기 위한 유역특성으로는 유역면적, 유역경사, 유역평균강우 등을 사용하였다. Bayesian-GLS (B-GLS) 적용 결과를 OLS(Ordinary Least Square) 및 Bayesian-GLS 기법에서 지점간의 상관관계를 고려하지 않는 Bayesian-WLS(Weighted Least Square)와 비교 평가하여 그 우수성을 입증하였다. 따라서 본 연구에서 제안된 B-GLS에 의한 지역회귀모형은 국내의 미계측유역이나 또는 관측 길이가 짧은 계측유역의 홍수빈도분석을 위해 매우 유용할 것으로 기대된다.년 홍수 피해가 발생하고 있지만, 다른 한편 인구밀도가 높고 1인당 가용 수자원이 상대적으로 적기 때문에 국지적 물 부족 문제를 경험하고 있다. 최근 국제적으로도 농업용수의 물 낭비 최소화와 절약 노력 및 타 분야 물 수요 증대에 대한 대응 능력 제고가 매우 중요한 과제로 부각되고 있다. 2006년 3월 멕시코에서 개최된 제4차 세계 물 포럼에서 국제 강 네트워크는 "세계 물 위기의 주범은 농경지", "농민들은 모든 물 위기 논의에서 핵심"이라고 주장하고, 전 프랑스 총리 미셀 로카르는 "...관개시설에 큰 문제점이 있고 덜 조방적 농업을 하도록 농민들을 설득해야 한다. 이는 전체 농경법을 바꾸는 문제..."(segye.com, 2006. 3. 19)라고 주장하는 등 세계 물 문제 해결을 위해서는 농업용수의 효율적 이용 관리가 중요함을 강조하였다. 본 연구는 이러한 국내외 여건 및 정책 환경 변화에 적극적으로 대처하고 물 분쟁에 따른 갈등해소 전략 수립과 효율적인 물 배분 및 이용을 위한 기초연구로서 농업용수 수리권과 관련된 법 및 제도를 분석하였다.. 삼요소의 시용 시험결과 그 적량은 10a당 질소 10kg, 인산 5kg, 및 가리 6kg 정도였으며 질소는 8kg 이상의 경우에는 분시할수록 비효가 높았으며 특히 벼의 후기 중점시비에 의하여 1수영화수와 결실율의 증대가 크게 이루어졌다. 3. 파종기와 파종량에 관한 시험결과는 공시품종선단의 파종적기는 4월 25일부터 5월 10일경까지 인데 이 기간중 일찍 파종하는 경우에 파종적량은 10a당 약 8${\ell}$이고 늦은 경우에는 12${\ell}$ 정도였다. 여기서 늦게 파종한 경우 감수의 가장 큰 원인은 1수영화수가 적어지기 때문이었다. 4. 건답직파에 대한 담수상태로 관수를 시작하는 적기는 파종후

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.483-491
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• 2021

The identification of regional collision risks in water areas is significant for the safety of navigation. This paper introduces a new method of collision risk assessment that incorporates a clustering method based on the distance factor - hierarchical clustering - and uses real-time data in case of several surrounding vessels, group methodology and preliminary assessment to classify vessels and evaluate the basis of collision risk evaluation (called HCAAP processing). The vessels are clustered using the hierarchical program to obtain clusters of encounter vessels and are combined with the preliminary assessment to filter relatively safe vessels. Subsequently, the distance at the closest point of approach (DCPA) and time to the closest point of approach (TCPA) between encounter vessels within each cluster are calculated to obtain the relation and comparison with the collision risk index (CRI). The mathematical relationship of CRI for each cluster of encounter vessels with DCPA and TCPA is constructed using a negative exponential function. Operators can easily evaluate the safety of all vessels navigating in the defined area using the calculated CRI. Therefore, this framework can improve the safety and security of vessel traffic transportation and reduce the loss of life and property. To illustrate the effectiveness of the framework proposed, an experimental case study was conducted within the coastal waters of Mokpo, Korea. The results demonstrated that the framework was effective and efficient in detecting and ranking collision risk indexes between encounter vessels within each cluster, which allowed an automatic risk prioritization of encounter vessels for further investigation by operators.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.149-157
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• 2003

Purpose: The purpose of this study was to determine if there were prognostic differences between BRCA related and BRCA non-related Korean patients with early-onset breast carcinomas. Materials and Methods: Sixty women who had developed breast cancers before the age of 40, and who were treated at the Soonchunhyang University Hospital, were studied independently of their family histories. The age range was 18 to 40 with a median of 34.5 years. Lymphocyte specimens from peripheral blood were studied for the heterozygous mutations of BRCA1 and BRCA2 using direct sequencing methods. Immunohistochemistry was peformed on the paraffin-embedded tissue blocks that were available. Results: Eleven deleterious mutations (18.3%, 6 in BRCA1 and 5 in BRCA2) and 7 missense mutations of unknown significance (11.7%), were found among the 60 patients. More than half of the mutation were novel, and were not reported in the database. Most of the BRCA-associated patients had no history of breast cancer. No treatment related failures were observed in the BRCA carriers, with the exception of one patient that had experienced a new primary tumor of the contralateral breast. The seven year relapse free survival rate were 50 and 79% In the BRCA carrier and BRCA negative patients, respectively. Although the expression of estrogen and progesterone receptors were less common, and histological features more aggressive, in the BRCA associated tumors, the outcome of the patients with BRCA mutations was not poorer than that on the patients without deleterious mutations. Conclusion.: Despite the BRCA mutation carriers having adverse prognostic features, the recurrence rate was relatively lower than that in the BRCA non-carrying Korean patients wi4h early-onset breast carcinomas. In addition, although the prevalence of the BRCA mutation in Korean patients was higher than that in white patients, the penetrance of the cancer seemed to be relatively low in Korean women carrying BRCA mutations. A large population based study of the BRCA mutation, with a long-term follow-up of the study patients will be required to confirm these results.

• Journal of the Mineralogical Society of Korea
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• v.27 no.2
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• pp.97-105
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• 2014

Artificial precipitation ponds, consisting of three steps of oxidation pond, successive alkalinity producing system (SAPS) and swamp, were constructed for the treatment of the acid mine drainage from the Iwal coal mine. The efficacies of the passive treatment system in terms of neutralization of mine water and removal of dissolved ions were evaluated by the chemical analyses of the water samples. Mine water in the mine adits was acidic, showing the pH value of 2.28-2.42 but the value increased rapidly to 6.17-6.53 in the Oxidation pond. The purification efficiencies for the removal of Al and Fe were 100%, whereas those of $SO_4$, Mg, Ca, and Mn were relatively low of 50%, 40%, 24%, and 59%, respectively. These results indicate a need for application of additional remediation techniques in the passive treatment systems. The precipitates that formed at the bottom of the mine water channels were mainly schwertmannite ($Fe_8O_8(OH)_6SO_4$) and those in the leachate water were 2-line ferrihydrite ($Fe_2O_3{cdot}0.5H_2O$).

• Journal of East-West Nursing Research
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• v.13 no.2
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• pp.92-106
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• 2007

Purpose: The purpose of this study was to examine nursing students' satisfaction level with PBL-based clinical practice, their autonomy, achievement motivation and what affected them in those regards in an attempt to lay the groundwork for providing more systematic and efficient clinical practice, Method: The subjects III this study were 138 nursing sophomores at J college who participated in PBL-based clinical practice, Results: They got a mean of 3.34, 3.83 and 3.83 in satisfaction level with the clinical practice, autonomy and achievement motivation respectively. In regard to the relationship of the satisfaction level to general characteristics including motivation of choosing the major and time for undergoing the clinical practice, the students who decided to major in nursing at their own option(3.61) were most contented with practice teaching(F=6.356, p<.01), and those who underwent the clinical practice after taking lessons(3.82) were most pleased with the content of the clinical practice (t=2.129, p<.05). Concerning connections between autonomy and general characteristics involving age, satisfaction with the major and time for the clinical practice, the students who were at the age of 22(3.92) valued themselves the most(F=3.003, P<.05). And those who found their major satisfactory (4.28) and undergo the clinical practice after taking lessons(4.37) respected others the most(F=3.133, p<.01). As to relations between achievement motivation and general characteristics, the students who were contented with their major(4.00) excelled the others who weren't in that aspect(F=6.038, p<.01). The satisfaction level with the clinical practice was positively correlated to autonomy (r=.328, p<.01) and achievement motivation(r=.476, p<.01). Conclusions: The findings illustrated that the nursing students expressed the satisfaction with the PBL-based clinical practice education. The older students who were 22 years old were more autonomous, and those who took part in the clinical practice after receiving theoretical instruction were more autonomous and more pleased with the practice. The students who found their major more satisfactory surpassed the others in autonomy and achievement motivation. There was positive correlation among the clinical-practice satisfaction level, autonomy and achievement motivation. There are some suggestions: Intensive research efforts should be directed into getting a profound grasp of PBL-based clinical practice education geared toward nursing students. The development of modules for PBL-based nursing clinical practice education was required. How to provide PBL-based theoretical education to nursing students should be studied.

• Journal of Korean Academy of Nursing
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• v.25 no.2
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• pp.244-258
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• 1995

아기의 출생은 부모에게 환경적, 신체적, 정신적 부담을 준다. 이렇게 부모가 된 사람들은 부모역할 수행시 어려움을 겪고 있고, 그 중에서도 어머니가 아버지보다 역할수행시 더 많은 어려 움을 겪고 있다고 한다. 본 연구는 생후 8개월 된 아기 어머니들을 대상으로 역할이 론을 토대로 모성역할 획득에 영향을 주는 요인들로 가설적 모형을 구축하고, 이의 적합성을 검정하므로 써 어머니들의 모성역할 획득을 촉진하기 위하여 필요한 간호 정보를 제공하려고 한다. 본 연구는 문헌고찰을 통하여 모성역할 긴장과 모성역할 획득에 영향을 주는 요인으로 일상생활의 시간적 여유, 아기 기질, 사회적 지지가 포함되었고, 모성역할 긴장이 모성역할 획득에 영향을 주는 것으로 이론적 기틀을 구성하였다. 연구도구로는 모성역할 획득 중 모성 정체감을 측정하기 위해 Osgood(Walker et al., 1986a에서 인용)도구, 모성역할 수행을 측정하기 위해 수정보완 된 Gibaud-Wallston(1977)도구와 어머니가 지각한 모아 상호작용정도 도구를 이용하였고, 모성역할 긴장측정에는 수정 보완된 Hobbs(정, 1985에서 인용)도구를 이용하였다. 아기 기질은 수정 보완한 The degree of thor inventory(Mercer, 1986 에서 인용), 남편의 정신적지지 측정은Taylor(Durrett, 1986에서 인용)의 도구를 이용하였고, 일상생활의 시간적 여유, 남편의 신체적 지지 및 주위의 지지측정은 연구자가 개발한 도구를 사용하였다. 1993년 1월부터 1994년 1월까지 대전시 5개 보건소에 등록된 대상자들에게 우편으로 설문지를 보내어 221명이 회수되어 회수율이 약72%였다. 일반적인 서술적 자료 분석은 SPSS PC+ 를 이용하였고, 가설적 모형은PC-LISREL 7.13 (Joreskkog & Sorbom,1988)프로그램을 이용하여 공변량구조분석을 하였다. 연구결과는 다음과 같다. 모성역할 획득에 모성역할 긴장, 일상생활의 시간적 여유, 아기 기질, 사회적 지지가 영향을 주며, 모성역할 긴장에는 일상생활의 시간적 여유, 아기 기질, 사회적지지가 영향을 준다고 설정된 가설적 모형〈Figure 1〉의 분석 결과 전반적 지수는 자유도 23에 카이자승치 60.17, GFI와 AGFI의 값은 .944, .891였고, NFI와 NNFI의 값은 .8823, .7932 이었다. 그러나 세부적 지수 중 모성역할 긴장에서 모성역할획득으로의 경로, 일상생활의 시간적 여유에서 모성역할 획득으로의 경로, 아기 기질에서 모성역할 획득으로의 경로의 고정지수가 절대치 2에 미치지 못하여, 세 경로계수를 영(0)으로 고정시킬 필요가 있었다. 따라서 더 간명하며 부합도가 좋은 모형을 찾기 위하여 가설적모형에서 고정지수가 낮은 경로 부터 고정시켜 나가 세경로(모성 역할 긴장에서 모성역할 획득, 일상생활의 시간적 여유에서 모성역할 획득, 아기 기질에서 모성역할획득)를 고정시킨 수정 모형 의 PFI (간명도)가 .5986으로서 가설적모형의 PFI(간명도) .5636보다 커 부합도 를 손상하지 않고 더 간명한 모형으로 나타났다. 수정모형 의 고정 지수를 살펴 본 결과 절대 치 2에 미치지 못하는 경로는 나타나지 않았다. 공변량구조분석 결과 나타난 변인간의 관계를 보면 가) 모성역할 긴장은 사회적 지지가 많을수록(Lisrel Estimates=-1.591), 아기 기질이 순하다고 생각할수록(Lisrel Estimates=-.266), 일상생활의 시간적 여유가 많을수록(Lisrel Estimstes=-1.771) 낮았고, 나) 모성역할 획득은 사회적 지지가 많을수록(Lisrel Estimates=1.120) 잘 되었다.