• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.463-468
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• 2011

The prospect of Arctic trade transportation opening on a year-round basis creates a vast opportunity of exploring untapped resources and shortened navigational routes. However, the environment's remoteness and lack of technical experiences remains a big challenge for the maritime industry. With this, engine designers and makers are continually investigating, specifically optimizing propulsion shafting system design, to meet the environmental and technical challenges of the region. Further, classification societies recognize the need to upgrade the Unified Rules concerning elements to meet current Polar requirements. Hence in this paper, excitation torque calculation on Polar class vessels propulsion shafting system will be reviewed. The propeller - ice interaction load effect, which is a main consideration of excitation source of Polar Class propulsion shafting system, on shaft design calculation will be analyzed.

• Journal of Ship and Ocean Technology
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• v.11 no.3
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• pp.24-38
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• 2007

It is a very challenging work to design large Arctic LNG carrier, since LNG carrier requires high reliability for the structural safety and the environment of Arctic region is known to be very severe. Therefore, special attention should be paid for the verifying the structural safety of LNG career particularly with regard to LNG leakage. In this paper, the safety of the hull structure and cargo containment system of 208K MK $III^{TM}$ type LNG carriers with Arc4 is investigated based on the direct calculation of ice loads as well as wave loads. From the whole investigation, it is clear that the developed vessel - 208K MK $III^{TM}$ type LNG carrier with RMRS Ice class Arc4 - has enough strength and is safe to be operated in Arctic region.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.5
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• pp.321-328
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• 2015

In recent years, there has been an increasing demand to apply the new IACS(International Association of Classification Societies) standards for ice and polar-classed ships. For ice-class vessel propulsion system, the ice impact torque design criterion is defined as a periodic harmonic function in relation to the number of the propeller blades. However, irregular or transient ice impact torque is assumed to occur likely in actual circumstances rather than these periodic loadings. In this paper, the reliability and torsional vibration characteristics of a comparatively large six-cylinder marine diesel engine for propulsion shafting system was examined and reviewed in accordance with current regulations. In this particular, the transient ice impact torque and excessive vibratory torque originating from diesel engine were interpreted and the resonant points identified through theoretical analysis. Several floating ice impacts were carried out to evaluate torque responses using the calculation method of classification rule requirement. The Newmark method was used for the transient response analysis of the whole system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.154-156
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• 2014

지구온난화로 2000년대 초부터 급격하게 감소하던 북극의 해빙이 2012년 이후로 다소 주춤한 상태로 돌아서고 있다. 그러나 최근 북극항로를 이용하는 선박의 척수와 화물량은 꾸준히 증가하고 있어 이 항로에 대한 세계적인 관심이 집중되고 있다. 중세의 문명의 교류가 오아시스 루트와 초원 루트 그리고 말라카 해협을 통한 해상실크로드를 통해 이루어진 것처럼, 장차 아시아와 유럽을 잇는 북극항로가 신해양실크로드가 될 것인지 북극을 둘러싼 여러 가지 상황을 살펴보고자 한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1166-1176
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• 2011

The prospect in opening the arctic trade transportation route on a year-round basis offers vast opportunity of exploring untapped resources and shortened navigational routes. In addition, the environment's remoteness and lack of technical experiences remains a big challenge for the maritime industry. With this, engine designers and makers are continually investigating, specifically optimizing propulsion shafting system design, to meet the environmental and technical challenges of the region. The International Association of Classification Society, specifically machinery requirements for polar class ships(IACS UR13), embodies the propulsion shafting design requirements for ice class vessels. However, the necessity to upgrade the various features of the unified rules in meeting current polar requirements is acknowledged by IACS and other classification societies. For the polar class propulsion shafting system, it is perceived that the main source of excitation will be the propeller - ice load interaction. The milling - and the impact load, in addition to the load cases interpreted by IACS, contribute greatly to the overall characteristic of the system and due considerations are given during the propulsion design stage. This paper will expound on the excitation load estimation factors affecting the dynamic response of the different propulsion shafting system design. It is anticipated that detailed understanding of these factors will have a significant role during propulsion shafting design in the future.

• Bulletin of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.3-7
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• 2010

국내 조선소와 학교, 연구소에서 1990년대 중반 이전의 빙해선박에 대한 연구는 거의 이루어지지 않았다고 해도 과언이 아니다. 하지만 2000년대 초반부터 러시아가 St. Petersburg항을 통해 본격적으로 원유를 수출하기 시작하면서 내빙선 시장이 호황을 맞이하게 되었고 빙해선박 특히 내빙선박에 대한 관심이 집중되었다. 당시에 한국의 조선소들은 FMA rule 상의 엔진 출력이 과도한 것을 인지하고, 적정한 엔진 사양을 파악하기 위한 공격적인 연구개발로 ICE Class 1A, 1B, 1C의 선박을 상당히 많이 수주하여 선주에게 인도하였다. 또한 Ice belt의 구조적인 보강을 하기위한 설계와 연구가 활발히 진행되었다. 내빙선에 이어 쇄빙선의 연구에 관심을 집중시킨 선박은 최근 실해역에서 활동 중인 연구 조사선 "아라온"호 이다. 아라온호는 설계와 건조가 국내 조선소에서 이루어졌으며, 학계와 조선소 및 연구소에 쇄빙선에 대한 관심을 불러 일으켰다. 이와 비슷한 시기에 삼성 중공업에서 세계 최대 쇄빙선인 70K shuttle tanker를 수주 및 인도하면서 대형 쇄빙선 시장이 개척되어 국내외 조선소의 큰 관심을 불러일으키고 있다. 쇄빙 기술이 응용된 선박으로 Drill ship과 LNG FPSO등이 수주되어 현재 설계를 진행 중이다. 가장 최근에 현대중공업에서 수주한 원통형 FPSO의 경우 북해 지역에 투입을 목적으로 언론에 발표된 것과는 달리 발주처와 유럽의 관련 연구기관에서는 러시아 유전지역 투입을 염두에 두고 쇄빙관련 연구를 진행한 것으로 파악되고 있다. 본 기고에서는 이러한 빙해선박의 개발 및 건조 사례 현황을 기술하고, 향후 수주가능성이 있는 쇄빙선 분야와 조선소의 대응 전략 등에 대해서 정리해 보고자 한다.

• Atmosphere
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• v.27 no.1
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• pp.17-28
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• 2017

The sensitivity of the typhoon track and intensity simulation to physics schemes of the global model are examined for the typhoon Bolaven and Tembin cases by using the Global/Regional Integrated Model System-Global Model Program (GRIMs-GMP) with the physics package version 2.0 of the Korea Institute of Atmospheric Prediction Systems. Microphysics, Cloudiness, and Planetary boundary Layer (PBL) parameterizations are changed and the impact of each scheme change to typhoon simulation is compared with the control simulation and observation. It is found that change of microphysics scheme from WRF Single-Moment 5-class (WSM5) to 1-class (WSM1) affects to the typhoon simulation significantly, showing the intensified typhoon activity and increased precipitation amount, while the effect of the prognostic cloudiness and PBL enhanced mixing scheme is not noticeable. It appears that WSM1 simulates relatively unstable and drier atmospheric structure than WSM5, which is induced by the latent heat change and the associated radiative effect due to not considering ice cloud. And WSM1 results the enhanced typhoon intensity and heavy rainfall simulation. It suggests that the microphysics is important to improve the capability for typhoon simulation of a global model and to increase the predictability of medium range forecast.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.66.2-66.2
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• 2013

As part of the DIGIT key program, we observed GSS30-IRS1, a Class I object located in Ophiuchus (d=125 pc), with Herschel-PACS. More than 70 lines were detected in 50-200 micron band including CO, OH, H2O, and [OI]. All lines, except for [OI], were detected only at the central spaxel of $9.4^{{\prime}{\prime}}{\times}9.4^{{\prime}{\prime}}$ while the [OI] emission is extended along the NE-SW direction. One interesting feature in GSS30-IRS1 is that the continuum is extended beyond PSF, unlike line emission. It suggests that the external heating is important in GSS30-IRS1. For detail analysis of line fluxes, we apply the non-LTE LVG model, RADEX as well as simple rotational diagrams. We also use the Monte Carlo radiative transfer package, RADMC-3D to understand the heating mechanism of dust grains around GSS30-IRS1. We will discuss about heating and cooling processes associated with GSS30-IRS1.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.88-90
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• 2013

최근 지구온난화의 영향으로 하절기 북극해의 얼음이 예상보다 빨리 녹고 있어 북극해항로의 상용화가 더욱 가속화될 전망이다. 지난해 여름 북극해빙의 크기는 1979년 인공위성관측 이래 최소치를 기록하였으며 또한 다년생 얼음구성비율도 낮아져 대부분이 1년생 얼음으로 대체됨으로써 선박의 운항기간도 점차 늘어나게 되었다.. 이러한 해빙의 가속화가 지속된다면 2030년경에는 북극해의 얼음이 완전히 녹을 것으로 예측되고 있다. 한편 러시아의 NSR 개방이후 비러시아 선박으로서는 2009년 독일 벨루가 선사 소속의 화물선 두 척이 NSR을 통과한 이래 지난 해에는 46척, 금년에는 그 수가 더욱 급격히 늘어나고 있어 앞으로 한.중.일의 NSR 선점경쟁이 더욱 치열해질 것으로 예상된다.

• Journal of The Korean Astronomical Society
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• v.40 no.4
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• pp.83-89
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• 2007

A new type of object called "Very Low Luminosity Objects (VeLLOs)" has been discovered by the Spitzer Space Telescope. VeLLOs might be substellar objects forming by accretion. However, some VeLLOs are associated with strong outflows, indicating the previous existence of massive accretion. The thermal history, which significantly affects the chemistry, between substellar objects with a continuous low accretion rate and objects in a quiescent phase after massive accretion (outburst) must be greatly different. In this study, the chemical evolution has been calculated in an episodic accretion model to show that CO and $N_2H^+$ have a relation different from starless cores or Class 0/I objects. Furthermore, the $CO_2$ ice feature at $15.2{\mu}m$ will be a good tracer of the thermal process in VeLLOs.